Dow AgroSciences Petitions (09-233-

01p, 09-349-01p, and 11-234-01p) for 

Determinations of Nonregulated Status 

for 2,4-D-Resistant Corn and Soybean 

Varieties

Final Environmental Impact Statement—August 

2014

Agency Contact: 

Sid Abel

Biotechnology Regulatory Services

4700 River Road 

USDA, APHIS 

Riverdale, MD 20737 

Fax: (301) 734-6352

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mentioned solely to report factually on available data and to provide specific information.

This publication reports research involving pesticides. All uses of pesticides must be registered by appropriate State and/or Federal agencies 

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Executive Summary

Summarized as “Protecting American Agriculture,” the mission of the United States Department 

of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) is “To protect the 

health and value of American agriculture and natural resources.” 1 APHIS regulates plant and 

animal health to achieve its mission. It integrates these regulatory functions to help ensure 

beneficial impacts on United States (U.S.) domestic agricultural production, commodities, trade

in agricultural products, and the environment.

One function critical to the APHIS mission is preventing the introduction and distribution of 

plant pests. This includes the management of certain plants, animals, and microorganisms that 

harm plants and cause economic losses to U.S. agriculture. It extends to practices and 

technologies that have the potential to increase plant pest risks.

The United States Department of Agriculture (USDA), Animal and Plant Health Inspection 

Service (APHIS) received three requests (petitions) from Dow AgroSciences (DAS) seeking 

determinations of nonregulated status for genetically engineered (GE) plant varieties referred to 

as: DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean (also known as 

EnlistTM corn and soybean). Currently, these GE plant varieties are regulated by APHIS, and 

Dow is seeking authorization from APHIS to grow these varieties without any APHIS regulatory 

oversight. Since these three GE plant varieties are currently under APHIS’ regulatory oversight, 

Dow must comply with a full range of safeguarding measures to ensure that these regulated GE 

plant varieties do not transfer or spread from their outdoor plantings while under regulation. A 

permit is also required to move these regulated varieties interstate. Even if APHIS grants 

authorization to Dow to grow these varieties, two other agencies, the U.S. Food and Drug 

Administration (FDA) and the U.S. Environmental Protection Agency (EPA), also provide 

oversight of genetically engineered plants (described below). 

As described in more detail below, APHIS authority for regulation of certain GE organisms is 

provided in the Plant Protection Act. Once a developer of a GE plant has obtained enough 

information to conclude that its regulated GE plant is unlikely to cause injury, damage, or 

disease to plants or plant products (that is, pose a plant pest risk), the developer may petition 

APHIS to remove the GE plant from regulation. Usually the petition is received when the 

developer wishes to commercialize a specific GE plant variety. This petition is referred to as 

seeking “nonregulated status” or as requesting a “deregulation.” If the petition for nonregulated 

status is approved by APHIS, then APHIS’ permits would no longer be required to grow or ship 

the genetically engineered plant and its progeny throughout the U.S. and its territories. This 

scenario would be the case if APHIS determines that nonregulated status is appropriate for one 

or more of the three Dow GE varieties. If nonregulated status is granted, herbicide applications 

1

For more details about the APHIS mission, visit http://www.aphis.usda.gov/about_aphis/

i

 
to these crops would still be under EPA oversight and food safety of the crops would still be 

under FDA oversight as described below. 

Regulatory Authority

APHIS regulates certain GE organisms under authority provided in the Plant Protection Act 

(PPA) of 2000 as amended (7 U.S.C. §§ 7701–7772), and by APHIS’ regulations codified in 

Title 7, part 340 of the U.S. Code of Federal Regulations (7 CFR part 340). APHIS’ part 340 

regulations govern a GE organism: if it is a plant pest (such as certain microorganisms or insects 

that can cause injury or damage to plants); or, if it is created using an organism that is itself a 

plant pest; or, if APHIS does not know or cannot determine if the GE organism is or may be a 

plant pest. 

Any party can petition APHIS for “nonregulated status” of a GE organism (that is, to discontinue 

regulating a GE organism that falls under its regulations) through the procedures described in 7 

CFR § 340.6. APHIS regulates such a GE organism until the agency evaluates whether the GE 

organism meets the PPA definition of a plant pest and concludes on the basis of scientific 

evidence that the GE organism is unlikely to pose a plant pest risk; that is to say that the potential 

for the GE organism to cause plant disease or damage is unlikely. In this case, the petitioner must 

provide data usually gathered through confined field tests regulated by APHIS to help inform the 

agency’s decision. APHIS analyzes the data from the petitioner, researches current scientific 

findings, and prepares a plant pest risk assessment (PPRA) that documents whether or not the GE 

organism is likely to cause disease or damage. If APHIS concludes that the GE organism is 

unlikely to pose a plant pest risk, APHIS must then issue a regulatory determination of nonregulated status, since the agency does not have regulatory authority to regulate organisms that 

are not plant pests. When a determination of nonregulated status has been issued, the GE 

organism may be introduced into the environment without APHIS’ regulatory oversight. If nonregulated status is determined for the GE corn and soybeans discussed in this EIS, Dow will be 

able to market the GE seeds to farmers for planting, and farmers will be able to grow, harvest,

and move their crop into commerce for food and feed without any further authorization from 

APHIS.

Two other agencies, the U.S. Food and Drug Administration (FDA) and the U.S. Environmental 

Protection Agency (EPA), also provide oversight of genetically engineered plants. The relative

roles of the USDA (through APHIS), FDA, and EPA are described in the “Coordinated 

Framework,” a 1986 policy statement from the Office of Science and Technology Policy that 

describes the comprehensive policy for ensuring the safety of biotechnology research and 

products (US-OSTP, 1986). 

The FDA’s regulation of genetically modified plants is based upon its authority to regulate food 

safety under the Federal Food, Drug, and Cosmetic Act (FFDCA) 21 U.S.C. §§ 301 – 399. The 

FDA has the authority to remove adulterated food from the national food supply, which could 

include removing food derived from genetically modified plants. 

The EPA governs the use, sale, and labeling of herbicides used on all plants pursuant to its 

authority under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (7 U.S.C. §§ 

ii
136–136y). FIFRA governs the use, sale, and labeling of herbicides and the EPA’s actions under 

FIFRA directly affect the production methods used on herbicide resistant GE plants. An 

herbicide must first be “registered” by the EPA before it can be distributed or sold in the United 

States (7 U.S.C. §§ 136a(a),136j(a)(2)(F)). The EPA registration process starts with the herbicide 

manufacturer providing the EPA with information about the herbicide (7 U.S.C. §136a(c)(1)(C), 

(F)). The agency then evaluates any adverse effects it may have on humans and the environment. 

On the basis of this evaluation, the EPA then determines if it will allow the herbicide’s use on a 

plant, and, if so, in what quantity. The EPA sets the conditions for the herbicide’s use and places 

them in labeling instructions that a user must follow (see 7 U.S.C. §136j(a)(2)(G)). The EPA 

reevaluates the herbicide every fifteen years, as part of a “re-registration process” in which the 

agency determines if it should continue allowing the herbicide’s use (7 U.S.C.§

136a(g)(1)(A)(iv)). The EnlistTM corn and soybean that are the subject of this EIS have been 

engineered to be resistant to the herbicide 2, 4-D. The EPA re-registered 2,4-D in 2005 (USEPA, 2005b). EPA is currently reviewing the use of 2,4-D on EnlistTM corn and soybean to 

determine whether the herbicide would cause any unreasonable environmental risks if it were

applied in accordance with its labeling instructions. The EPA does not regulate EnlistTM corn and 

soybean plants, because the plant itself does not produce or secrete a pesticide.

Purpose of EnlistTM Corn and Soybean

Dow has developed EnlistTM GE plant varieties as alternatives to currently available GE 

herbicide-resistant (HR) corn and soybean varieties (see the petitions which are available on 

APHIS’ website http://www.aphis.usda.gov/biotechnology/petitions_table_pending.shtml). 

Many HR corn and soybean varieties have been engineered over the past 15 to 20 years. These 

include varieties with resistance to the herbicide glyphosate (the active ingredient in Roundup®); 

varieties resistant to the herbicide glufosinate (the active ingredient in the herbicide Liberty®); 

varieties resistant to a class of herbicides known as sulfonylureas (active ingredients in 

herbicides such as Glean®); varieties resistant to the synthetic auxin known as dicamba (the 

active ingredient in herbicides such as Banvel®)

, and varieties resistant to isoxaflutole and 

mesotrione (the active ingredient in herbicides such as Balance® and Callisto®). By far, Roundup

Ready® crops have been the most widely adopted by growers. Roundup Ready® crops greatly 

simplified weed management for growers and reduced their weed management costs. These 

Roundup Ready® crops were so successful that many growers grew only Roundup Ready® crops 

on their farms. As another example of this success, most soybean growers could manage weeds 

by using glyphosate as the only herbicide, whereas three to four herbicides were previously 

needed. 

This nearly exclusive use of glyphosate over the past fifteen years led to the selection of 

glyphosate-resistant (GR) weeds, weeds that could survive an application of the herbicide that 

once would kill earlier generations. Herbicides do not create resistant weeds, but rather, through 

time, individual plants may survive a treatment. In a field of weeds, individual plants vary in 

their genetic makeup and in their resistance to a particular herbicide. Plants that survive the 

herbicide treatment may produce seed, resulting in even more plants that are resistant to the 

herbicide. Plants that are not resistant die and do not leave off-spring. In this way, the herbicide 

“selects” for resistant plants and against sensitive plants and the resistant plants are disseminated 

iii
as a result of seed production and dispersal. (To read more about herbicide-resistant weeds see 

Appendix 6.) 

Where GR weeds are widespread, the benefits of the Roundup Ready® system are diminished,

and weed management is more costly. To manage GR weeds, growers have reverted to other 

herbicides and to mechanical cultivation practices used to manage weeds before the introduction 

of Roundup Ready® crops. Growers are also increasingly adopting glufosinate-resistant and other 

HR crops. (To read about the socioeconomic impacts of resistant weeds, see Section 5.7.1.)

The primary purpose of EnlistTM corn and soybean varieties is to help growers manage GR 

weeds. Each of the EnlistTM varieties has a trait that makes the plant resistant to the herbicide 

2,4-D. 2,4-D is an active ingredient in hundreds of herbicide formulations and is commonly 

found in lawn care products (for example Scotts® Turf Builder® Weed and Feed). These 2,4-D 

products are used by homeowners and professional lawn care companies. Many lawn grasses are 

naturally resistant to 2,4-D. It is the third most widely used herbicide in the U.S. (glyphosate and 

atrazine are number one and two, respectively) and is widely available to consumers at retail 

outlets and home and garden centers. 2,4-D is also a relatively inexpensive herbicide. 

Increasingly, corn and soybean growers are using herbicide formulations that contain 2,4-D to 

manage GR weeds, often applying the herbicide before planting the crop. (To read more about 

trends in herbicide use on corn and soybean see Appendix 4.) Corn, for example, is naturally 

resistant to 2,4-D during certain early stages of growth. The EnlistTM traits would allow growers 

to apply 2,4-D when the corn is older. 

EnlistTM corn is also resistant to, quizalofop, an herbicide found in herbicide formulations such 

as Assure® and Matador®. Corn is normally sensitive to quizalofop and this herbicide is 

sometimes used to control corn volunteers (i.e., corn that sprouts in fields now being used to 

grow so-called rotation crops such as soybean). Therefore, these herbicide formulations would 

no longer be useful for controlling volunteer EnlistTM corn in soybean fields. (For more 

discussion of the control of corn volunteers see Plant Communities in Section 4.1.2.)

Soybean is extremely sensitive to 2,4-D, so the herbicide can only be used on soybean fields at 

least 30 days before planting the soybeans. In contrast, growers could apply 2,4-D to soybeans 

with the EnlistTM trait, after the soybeans start to grow, killing the weeds but not the soybeans. 

Consequently, EnlistTM soybean will be valuable to control the many weeds that begin to grow 

later in the season after the soybean has begun to grow. 

In addition to resistance to 2,4-D, the commercial seed varieties of EnlistTM corn are expected to 

have resistance to glyphosate and quizalofop and the commercial varieties of soybean are 

expected to have resistance to glyphosate and glufosinate. For the technical details on the 

creation of these three GE plants, see the petitions which are available on APHIS’ website 

(http://www.aphis.usda.gov/biotechnology/petitions_table_pending.shtml). 

Purpose and Need for Agency Action

APHIS’s regulations require that APHIS make decisions on the petitions it receives for 

nonregulated status. The Agency can choose to approve a petition in whole or in part, or it can 

iv
deny the petition. The decision is based on a plant pest risk assessment for the GE plants that are 

the subject of the petition. Plant pest risks are those risks that can cause injury, damage, or 

disease to plants or plant products. 

The purpose of the petition process and the decisions made under the regulations is to protect 

plant health. Developers who can demonstrate through this process that their products do not 

cause plant pest risks can enter their products into commerce without restrictions after a 

determination of nonregulated status is made. APHIS must make a decision that is consistent 

with the Agency’s regulatory and statutory authority.

Public Involvement

In response to the receipt of the three Dow petitions, APHIS prepared preliminary PPRAs to 

assess the plant pest risk for each plant variety. Additionally, APHIS conducted an 

environmental analysis consistent with its obligations under the National Environmental Policy 

Act (NEPA). NEPA regulations provide that an agency shall conduct an environmental 

assessment (EA) to determine if an agency action will significantly affect the environment (40 

CFR § 1501.4). If the agency concludes in its EA that its action will not significantly impact the 

environment, the agency issues a “Finding of No Significant Impact,” and the agency can 

proceed with its proposed action without preparing an environmental impact statement (EIS). If 

this initial assessment finds that the agency’s action may significantly affect the environment, the 

agency must then prepare an EIS.

APHIS examined the environmental impacts of its potential decisions for nonregulated status of 

the EnlistTM corn and soybean by preparing EAs for two of the three petitions: petition 09-233-

01p for EnlistTM corn and petition 09-349-01p for EnlistTM soybean (this EA only considered the 

EnlistTM soybean variety, DAS-68416-4). Each EA included a public comment period (corn: 

December 27, 2011-February 27, 2012; soybean: July 13-2012-September 11, 2012). For the 

corn and soybean EAs, comments are accessible at 

http://www.regulations.gov/#!documentDetail;D=APHIS-2010-0103-0001 and 

http://www.regulations.gov/#!documentDetail;D=APHIS-2012-0019-0001. An EA was not 

prepared for the EnlistTM soybean variety, DAS-44406-6, because it was submitted considerably 

later than the other EnlistTM corn and soybean petitions. By the time an EA would have been 

started, a decision had been made to prepare an EIS for all three of the EnlistTM plant varieties. 

As an EIS involves a more detailed environmental review, an EA was no longer necessary. 

APHIS has included the petition 11-234-01p corresponding to the EnlistTM soybean DAS-44406-

6 in this EIS analysis because this soybean variety exhibits the same or similar HR traits as DAS68416-4 soybean, so it presents similar environmental issues. APHIS also had a public comment 

period on the Notice of Intent (NOI) to prepare this EIS (May 16, 2013-July 17, 2013). APHIS 

received 41 comments on the NOI (See Appendix 2).

The draft EIS was available for public comment from January 10, 2014-March 11, 2014. APHIS 

held a public meeting on the draft EIS attended by 110 participants. Twenty four participants 

made comments, with 9 opposed and 15 in favor of deregulation (APHIS-2013-0044). APHIS 

received 10,147 submissions on the draft EIS docket (APHIS 2013-0042). Of these 8940 

opposed and 1082 supported the use of EnlistTM corn and soybean. The remaining 125 comments 

v
consisted of submission of attachments, requests for extensions, or were submissions to the 

wrong docket. The comment summary and responses to the draft EIS are included in Appendix 

9. 

During the comment periods, the public identified three main issues. Following is a brief 

representation of those issues with a summary of our responses:

1) The concern that natural and biological resources would be adversely impacted by 2,4-D 

in anticipation of increased amounts of this herbicide being used on EnlistTM corn and 

soybean should these products be deregulated.

Although many commenters raised the issue about the potential for adverse impacts to the 

environment from the expected increased use of 2,4-D, these direct and indirect impacts are 

outside the scope of this EIS because the authority to regulate the impacts of herbicide use 

resides with the EPA under FIFRA. The EPA has conducted independent assessments of 

direct and indirect effects associated with the use of 2,4-D on EnlistTM corn and soybean 

(US-EPA, 2013a; b; c) and is making an independent action to determine whether to approve 

registration of Enlist DuoTM (US-EPA, 2014).USDA’s authority comes from the Plant 

Protection Act, which limits APHIS authority to the regulation of plant pests and noxious 

weeds only. The three petitions submitted by Dow are evaluated pursuant to Part 340. Under 

APHIS’s Part 340 regulations, APHIS can only consider plant pest risks when making a 

determination of nonregulated status. APHIS has no authority to regulate herbicide use. The

EPA’s registration process under FIFRA ensures that pesticides will be properly labeled and 

that, if used in accordance with label specifications, pesticides will not cause unreasonable 

harm to humans and the environment. Thus, the EPA has the authority to regulate the effects

of herbicide use on humans and the environment. The EPA’s regulatory responsibilities are 

more fully discussed in Section 1.4.2. The risk assessments used by the EPA are explained in 

Section 5.4.

2) The need by growers for EnlistTM corn and soybean to help them manage GR weeds 

already present on many farms across the country. 

Growers are changing management practices to manage GR weeds including increasing 

tillage, hand weeding, and use of different herbicide chemistries. APHIS considers the 

impacts of GR weeds in the No Action Alternative (Section 4.1.1 Herbicides). EnlistTM crops 

will allow the post-emergent use of 2,4-D for weed control. In this way, they are expected to 

better enable growers to manage GR weeds. APHIS considers the potential for its decision on 

these petitions, combined with EPA’s decision on the labeling of the Enlist DuoTM herbicide 

(a combination of 2,4-D and glyphosate) to influence management practices and to control 

GR weeds in Chapter 5. 

3) The concern that increased use of 2,4-D on EnlistTM corn and soybean would hasten the 

selection of 2,4-D-resistant weeds.

APHIS has identified the possible selection of HR weeds resulting from the change in 

management practices associated with the adoption of EnlistTM corn and soybean as a 

potentially significant environmental impact. This impact is a cumulative impact because it 

would only result from the combined action of USDA on the subject petitions and of the 

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EPA’s action to register 2,4-D for use on EnlistTM corn and soybean. If 2,4-D-resistant weeds 

were to be selected as a result of these combined actions, growers who rely on 2,4-D for 

effective and inexpensive weed control are likely to experience increased socioeconomic 

impacts from more costly and restrictive weed control alternatives.

Because of the likely adverse socioeconomic impacts that would result in the event that 2,4-Dresistant weeds would be selected from the expected increased 2,4-D use on EnlistTM crops, 

APHIS believed these impacts may be significant. Therefore APHIS decided, for the three 

EnlistTM varieties that are the subject of this EIS, to exercise its discretion to prepare an EIS to 

further analyze the potential for selection of 2,4-D-resistant weeds and other potential impacts 

that may occur from making determinations of nonregulated status for these varieties. This EIS 

limits its analysis of herbicide use to the cumulative impacts that occur from the selection of HR

weeds and the changes in management practices that result so as not to duplicate the analysis 

independently conducted by the EPA (US-EPA, 2013a; b; c) (US-EPA, 2014)

Alternatives Analyzed

In this EIS, APHIS considers four alternatives regarding the possible deregulation of these three 

GE organisms. The four alternatives are: (1) No Action; (2) approve the petitions for 

nonregulated status of EnlistTM corn and soybean; (3) approve the petition for nonregulated status 

of EnlistTM corn only; and (4) approve both petitions for nonregulated status of Enlist soybeanTM 

only. 

Alternative 1: No Action Alternative—Continuation as Regulated Articles

Under the No Action Alternative, APHIS would deny the three petitions and these GE plant 

varieties would continue to be regulated by APHIS. Permits issued or notifications 

acknowledged by APHIS would still be required for the introduction of EnlistTM corn and 

soybean, and measures to ensure physical and reproductive confinement would continue to be 

implemented. This Alternative is not the Preferred Alternative because APHIS has concluded in 

its PPRAs that EnlistTM corn and soybean are unlikely to pose plant pest risks (USDA-APHIS, 

2010b; 2012a; b). Choosing this alternative would not satisfy the purpose and need of making the 

required regulatory determination that is consistent with the PPA and 7 CFR part 340.6.

Alternative 2: Determination of Nonregulated Status of DAS-40278-9 Corn, DAS-68416-4 

Soybean, and DAS 44406-6 Soybean (Preferred Alternative)

Pursuant to its PPA authority, as implemented in 7 CFR part 340, APHIS must respond to a 

petition to reclassify a regulated article as not subject to regulation under the plant pest

provisions of the PPA. Under this alternative, EnlistTM corn and soybean and their progeny 

would no longer be subject to APHIS biotechnology regulations (7 CFR part 340). Permits 

issued or notifications acknowledged by APHIS would no longer be required for introductions of 

these varieties. This alternative meets the purpose and need to respond appropriately to the 

petitions (DAS, 2010a; DAS, 2010b; DAS, 2011) for nonregulated status, the requirements in 7 

CFR part 340, and the Agency’s regulatory authority under the plant pest provisions of the PPA, 

because these varieties are unlikely to pose plant pest risks as evaluated in the PPRA (USDAAPHIS, 2010b; 2012a; b). Therefore, this is the Preferred Alternative because approving the 

vii
petitions for nonregulated status for all three varieties is consistent with the plant pest provisions 

of the PPA and the regulations codified in 7 CFR part 340.

Alternative 3: Approve the Petition for a Determination of Nonregulated Status of DAS

40278-9 Corn Only

Under this alternative, only EnlistTM corn and progeny derived from its cultivation would no 

longer be subject to the PPA regulations. Permits issued or notifications acknowledged by 

APHIS would no longer be required for this corn and its progeny. This alternative meets the 

purpose and need to respond appropriately to the petition for nonregulated status for EnlistTM

corn, the requirements in 7 CFR part 340 and the Agency’s regulatory authority under the plant 

pest provisions of the PPA, because it is unlikely to pose a plant pest risk evaluated in the PPRA

(USDA-APHIS, 2010b; 2012a; b). Therefore, approving the petition for a determination of 

nonregulated status for EnlistTM corn is consistent with the plant pest provisions of the PPA and 

the regulations codified in 7 CFR part 340. However because APHIS has concluded in its PPRAs

that the two EnlistTM soybean varieties are unlikely to pose plant pest risks (USDA-APHIS, 

2010b; 2012a; b), choosing this alternative would not satisfy the purpose and need of making the 

required regulatory determination that is consistent with the PPA and 7 CFR part 340.6.

Alternative 4: Approve the Petition for a Determination of Nonregulated Status of DAS68416-4 Soybean and DAS-44406-6 Soybean Only

Under this alternative, only the two EnlistTM soybean events (an event is a plant line produced 

from the insertion of a specific DNA into a plant species) and progeny derived from their 

cultivation would no longer be subject to the PPA regulations. Permits issued or notifications 

acknowledged by APHIS would no longer be required for their introduction and progeny derived 

from them. This alternative meets the purpose and need to respond appropriately to the petitions 

(DAS, 2010b; DAS, 2011) for nonregulated status for the two EnlistTM soybean varieties, the 

requirements in 7 CFR part 340 and the Agency’s regulatory authority under the plant pest 

provisions of the PPA, because it is unlikely that they pose a plant pest risk evaluated in the 

PPRA (USDA-APHIS, 2010b; 2012a; b). Therefore, the Agency’s deregulation of the two 

EnlistTM soybean varieties is consistent with the plant pest provisions of the PPA and the 

regulations codified in 7 CFR part 340. However, because APHIS has concluded in its PPRAs

that EnlistTM corn is unlikely to pose plant pest risks (USDA-APHIS, 2010b; 2012a; b), choosing 

this alternative would not satisfy the purpose and need of making the required regulatory

determination that is consistent with the PPA and 7 CFR part 340.6.

Affected Environment

In order to determine the extent of the potential environmental impacts that could result from 

APHIS’ decision whether to grant nonregulated status, APHIS used information provided by the 

National Agricultural Statistics Service (USDA-NASS) to identify those regions of the country 

where corn and soybeans are grown. To describe the ecological features of corn and soybean 

regions, APHIS compared these growing areas to maps that group regions having similar 

ecological attributes such as soil, landform, or major vegetation types (CEC 2009). These regions 

are termed ecoregions and are identified as Regions A through M in this EIS (see section 3.1.3). 

viii
To identify the types of land cover and crops grown in each region, APHIS analyzed information 

in the USDA-NASS online tool, “Cropscape” an information source that compiles these data 

from satellite imagery.

Potential Environmental Consequences of Alternatives

Environmental issues are assessed individually in Chapter 4 (Potential Environmental 

Consequences). As stated previously, APHIS has regulatory authority over the EnlistTM corn and 

soybean plants, and the EPA has regulatory authority over the EnlistTM Duo herbicide (a premix 

of 2,4-D and glyphosate). The scope of this EIS covers the direct and indirect impacts that would 

result from the cultivation and use of the plant. The EPA, in its registration process, is 

considering any direct and indirect impacts from the use of the herbicide on EnlistTM plants. The 

USDA is relying on the EPA’s authoritative assessments and will not duplicate the assessment 

prepared by the EPA. USDA also considers in this EIS (Chapter 5), cumulative impacts that 

result in the event that USDA approves the petitions for non-regulated status to EnlistTM corn and 

soybean and the EPA registers the use of herbicides on these crops. 

APHIS determined that EnlistTM corn and soybean varieties would not result in an increase in 

acres in areas already in corn and soybean production. In addition, APHIS determined that there 

were no direct or indirect impacts on the environment from the cultivation of EnlistTM corn and 

soybean plants themselves, because these GE varieties are not agronomically different from nonGE corn and soybean plants or other GE corn or soybean plants that are no longer regulated by 

the Agency. These three GE plant varieties do not affect natural (e.g., soil, water, air) or 

biological (e.g., animal, insect, plant) resources directly. Rather, the management practices (e.g., 

pesticide applications and tillage practices) associated with their use could impact natural and 

biological resources. For example, herbicide applications can lead to the selection of weeds 

resistant to that herbicide, and tillage can adversely affect soil, water, and air quality and increase 

greenhouse gas emissions. While EnlistTM corn and soybean can resist damage from the 

application of the Enlist DuoTM herbicide, APHIS’ selection of a particular alternative does not in 

itself allow the use of Enlist DuoTM herbicide on EnlistTM corn and soybean plant varieties. The 

EPA regulates the use of herbicides under FIFRA and is making a separate decision which may 

or may not allow use of Enlist DuoTM herbicide on these plants. 

In Chapter 5, the environmental analysis considers potential cumulative impacts, including how 

herbicide use may change if the requested EPA actions are approved in conjunction with those of 

APHIS. APHIS approval of the three petitions for nonregulated status for EnlistTM corn and 

soybean and the independent decision by EPA to register Enlist DuoTM herbicide for use on these 

GE plant varieties is reasonably foreseeable. This herbicide product contains a unique 

formulation of 2,4-D mixed with glyphosate devised to reduce the off-target movement of 2,4-D. 

Its use is required by a Stewardship Agreement for anyone planting EnlistTM corn and soybean. 

For more on off-target movement see Appendix 7. One farmer group, the Save Our Crops 

Coalition, consisting of growers who raise 2,4-D sensitive crops, was initially opposed to 

EnlistTM crops due to concerns about off-target movement from the application of 2,4-D. 

However, their position changed based on discussions between the Save our Crops Coalition and 

Dow. As a result of those discussions, Dow committed to foster stewardship practices by 

EnlistTM technology users and amended its pending label submitted to the EPA to include further 

ix
mitigation language (APHIS-2013-0042-7255 at regulations.gov). The mitigation language

aimed at drift reduction includes a requirement of EnlistTM technology users to use only Enlist 

DuoTM, a low volatility formulation, a specific nozzle type and maximum wind speed for 

application, applicator reporting requirements, and a 30-foot buffer zone from sensitive areas on 

areas to be sprayed.

As part of the cumulative impacts analysis, APHIS analyzed trends in 2,4-D use and, with 

information supplied by Dow, predicted 2,4-D use in the future under each of the Alternatives 

(see Appendix 4, Table 4-12). Based on the existing trend of increased use of 2,4-D over the last 

decade (i.e., without these 2,4-D-resistant crops), APHIS projects that 2,4-D use on crops will 

increase by nearly 75 percent by 2020 under the No Action Alternative. If EPA registers Enlist 

DuoTM herbicide for EnlistTM corn and soybean and APHIS adopts the Preferred Alternative,

APHIS expects that 2,4-D use will further increase on crops by 200 to 600 percent by 2020

(depending on the assumptions made) relative to current use.

Deregulation of EnlistTM crops and approval of use of 2,4-D on those crops will cause growers to 

change management practices; namely 2,4-D use is expected to increase beyond the increase 

expected without these crops. Furthermore, 2,4-D use is expected to be used over a wider part of 

the growing season. The change in management practices expected under the Preferred 

Alternative is expected to increase the pressure for selection of 2,4-D-resistant weeds. Growers 

themselves can influence this selection pressure by the management practices they choose. Some 

examples of the practices that can be followed to reduce or delay the selection of HR weeds 

include, rotating crops, rotating types of herbicides, using cover crops, scouting for weeds, and 

using mechanical tillage to prevent weeds from flowering(see Section 5.7.2 for additional 

discussion). Societies such as the Weed Science Society of America (WSSA), university 

extension agents, and industry, have made a concerted effort to increase grower awareness of 

best management practices for HR weeds (see for example APHIS-2013-0042-1911 and -6165). 

The extent to which growers will adopt best management practices is unknown and, therefore, it 

is difficult to accurately predict when and the extent to which 2,4-D-resistant weeds will become 

a problem. 

As noted above, 2,4-D is already the third most widely used herbicide in the United States. 

Among agricultural uses, 2,4-D is widely used for weed control on small grains (wheat, barley, 

oats, and sorghum) and orchards (see Appendix 4, Table 4-7 for a more complete list). If 2,4-D 

resistant weeds become more prevalent as a result of its use on EnlistTM corn and soybean, 

growers of these other crops that rely on 2,4-D for weed control may need to modify 

management practices to control weeds that become resistant to 2,4-D. The management changes 

would increase the complexity and cost of weed management programs for these growers. 

Growers most likely to be affected include those who grow small grains (See Chapter 5 for 

additional discussion). To identify which areas are most likely to experience cumulative impacts, 

APHIS identified areas where corn or soybean and small grains are grown in proximity and 

represent greater than 20 percent of cropland (see Chapter 5, Table 10). The areas identified 

include Ecoregion D (coastal southeast), Ecoregion F (Louisiana, Mississippi, Arkansas, 

Tennessee, Missouri); Ecoregion H (Western North Dakota and South Dakota); Ecoregion I 

(western Kansas, Nebraska, eastern Wyoming, eastern Colorado, and parts of western Texas and 

x
western Oklahoma); and Ecoregion J (central Texas). Because the use of EnlistTM corn and 

soybean does not require a single specific set of agronomic practices, the magnitude of the 

impacts discussed depends on the adoption rates of various practices by growers. While the 

selection pressure for 2,4-D-resistant weeds is expected to be greater under the Preferred 

Alternative, the selection pressure for GR weeds is expected to be greater under the No Action 

Alternative. This is because the EnlistTM cropping system decreases grower reliance on 

glyphosate by including an additional type of herbicide in the weed management system.

The continued emergence of GR weeds under the No Action Alternative will itself call for

modification of crop management practices to address these weeds. Growers are expected to 

become less reliant on glyphosate for the control of weeds it is no longer effective in controlling. 

Growers will likely continue to use the herbicide because it is still effective on hundreds of weed 

species. However, farmers are expected to use additional chemical and non-chemical methods to 

control the GR weeds, too. Changes in management practices are expected to include more use 

of non-glyphosate herbicides and adjustments to crop rotation and tillage practices (Owen et al., 

2011b). Herbicides that kill weeds by mechanisms (referred to as sites of action; see Appendix 3) 

different than glyphosate are expected to increase as growers face the need to manage GR weeds 

(see Figures 4.1 and 4.3 in Appendix 4). A site of action refers to the biochemical reaction that is 

affected by the herbicide. For example, glyphosate and glufosinate inhibit distinct reactions and 

therefore have different sites of action. 2,4-D affects yet another site of action. Current trends 

indicate that herbicides representing at least six sites of action are increasing in use and are 

expected to continue to increase under the No Action Alternative.

Selection of GR weeds is expected to continue where glyphosate is used. Areas where GR weeds 

are expected to remain a serious concern include the Southeast, Great Plains and Northern 

Crescent regions, where such weeds have already become widely prevalent. Furthermore, 

because other non-glyphosate herbicides will still be used to manage GR weeds, weeds resistant 

to non-glyphosate herbicides will continue to be selected. For many of the non-glyphosate 

herbicides, resistant weeds have already been selected and are widely prevalent (see Appendix 6 

for more details). As a result, herbicide options for weed management may become less 

attractive under the No Action Alternative and growers may be forced to return to more 

aggressive tillage systems to maintain soybean yields (Conley, 2013).

Under the Preferred Alternative, 2,4-D use is expected to increase relative to the No Action 

Alternative, if EPA approves the amended use of 2,4-D on these crops. However, increases in 

other herbicide sites of action under the Preferred Alternative are expected to be less than under 

the No Action Alternative because the Enlist DuoTM herbicide is expected to be preferentially 

adopted if approved for use on these crops by EPA. The availability of inexpensive and effective 

herbicides in Enlist DuoTM combined with EnlistTM corn and soybean may delay the adoption of 

non-chemical management strategies under the Preferred Alternative. Fewer growers would be 

expected to adopt aggressive tillage when herbicides remain effective for weed control. Selection 

of weeds resistant to glyphosate and non-glyphosate herbicides will still occur under the 

Preferred Alternative. The selection pressure for HR weeds under the Preferred Alternative 

relative to the No Action Alternative will depend on the management practices employed under 

xi
each alternative and cannot be predicted. More diversified weed management practices will 

result in less selective pressure for resistance to any given herbicide or management technique.

Under the No Action Alternative, natural resources are expected to be negatively impacted by a 

return to more aggressive tillage practices. If conventional tillage increases to control 

glyphosate- and other herbicide-resistant weeds, there may be an impact on soil quality from 

increased erosion; on air quality from increased air particulates and increased emission due to 

more use of farm equipment; on water quality from increased sedimentation; on climate change 

from increased release of greenhouse gases from burning additional fossil fuels and soil 

disruption that releases sequestered carbon; and on biodiversity from habitat loss. The total 

acreage that may be impacted by such an increase in tillage would be based on the extent of 

resistant weeds present in a field and the weed management strategy chosen by a grower. 

Adoption of EnlistTM soybean can provide growers with an alternative herbicide to glyphosate 

and glufosinate and could provide growers with an alternative to intensive tillage practices that 

may be used to manage HR weeds. However, the eventual occurrence of weeds resistant to 

glyphosate, 2,4-D and glufosinate will over time limit the use of EnlistTM crops and any benefit to 

natural resources that may arise. The magnitude of the benefit or the loss of the benefit is 

uncertain because decisions on crop production management are made by individual growers. 

xii
TABLE OF CONTENTS

ACRONYMS AND ABBREVIATIONS...................................................................... XIX

1 PURPOSE AND NEED.............................................................................................. 1

1.1 Introduction .......................................................................................................... 1

1.2 APHIS Regulatory Authority............................................................................... 1

1.2.1 Context for This FEIS................................................................................... 2

1.3 Purpose of These Products................................................................................... 3

1.3.1 DAS-40278-9 Corn....................................................................................... 3

1.3.2 DAS-68416-4 and DAS-44406-6 Soybean................................................... 4

1.4 Coordinated Regulatory Framework for Genetically-Engineered Organisms..... 4

1.4.1 USDA-APHIS............................................................................................... 5

1.4.2 Environmental Protection Agency................................................................ 5

1.4.3 Food and Drug Administration ..................................................................... 6

1.5 Purpose and Need for This APHIS Action........................................................... 7

1.6 Public Involvement .............................................................................................. 8

1.6.1 EIS Scoping: Public Comment Period.......................................................... 9

1.6.2 Public Comment Period for Draft EIS.......................................................... 9

1.6.3 Public Comment Period for Draft EA for Petition 09-233-01p.................... 9

1.6.4 Public Comment Period Draft EA for Petition 09-349-01p.......................... 9

1.6.5 Public Comment Period for Petition 11-234-01p ....................................... 10

1.7 Issues Considered............................................................................................... 10

2 ALTERNATIVES..................................................................................................... 11

2.1 Alternative 1: No-Action Alternative—Continuation as Regulated Articles..... 11

2.2 Alternative 2: Determination of Nonregulated Status of DAS-68416-4 Soybean, DAS 

44406-6 Soybean, and DAS-40278-9 Corn (Preferred Alternative) ................. 11

2.3 Alternative 3: Determination of Nonregulated Status of DAS-40278-9 Corn Only

........................................................................................................................... 12

2.4 Alternative 4: Determination of Nonregulated Status of DAS-68416-4 Soybean and 

DAS 44406-6 Soybean Only ............................................................................. 12

2.5 Alternatives Considered but Rejected from Further Consideration................... 12

2.5.1 Prohibit Any DAS-68416-4 Soybean, DAS-44406-6 Soybean, and DAS40278-9 Corn from Being Released ........................................................... 12

2.5.2 Approve the Petition(s) in Part ................................................................... 13

xiii
2.5.3 Production/Geographical Restrictions to Isolate DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, and DAS-40278-9 Corn from Non-GE Soybean or 

Corn ............................................................................................................ 13

2.5.4 Requirement of Testing for DAS-68416-4 Soybean, DAS-44406-6 

Soybean, and DAS-40278-9 Corn.............................................................. 14

2.6 Comparison of Alternatives ............................................................................... 14

3 AFFECTED ENVIRONMENT................................................................................ 26

3.1 U.S. Corn and Soybean Production Practices.................................................... 26

3.1.1 Corn............................................................................................................. 27

3.1.2 Soybean....................................................................................................... 27

3.1.3 Ecoregions of Major U.S. Corn and Soybean Production Areas................ 28

3.2 Physical Environment ........................................................................................ 32

3.2.1 Physical Terrain and Climate...................................................................... 32

3.2.2 Soil Resources............................................................................................. 34

3.2.3 Water Resources ......................................................................................... 38

3.2.4 Water Quality.............................................................................................. 41

3.2.5 Air Quality .................................................................................................. 41

3.2.6 Climate Change........................................................................................... 42

3.2.7 Land Resources........................................................................................... 44

3.3 Biological Resources.......................................................................................... 52

3.3.1 Animal Communities.................................................................................. 52

3.3.2 Plant Communities...................................................................................... 56

4 POTENTIAL ENVIRONMENTAL CONSEQUENCES ........................................ 57

4.1 No Action Alternative ........................................................................................ 57

4.1.1 Socioeconomic and Human Health............................................................. 57

4.1.2 Biological Resources .................................................................................. 87

4.1.3 Natural Resources....................................................................................... 94

4.2 Preferred Alternative ........................................................................................ 105

4.2.1 Socioeconomic and Human Health........................................................... 106

4.2.2 Biological Resources ................................................................................ 109

4.2.3 Natural Resources..................................................................................... 111

4.3 Alternative 3..................................................................................................... 112

xiv
4.4 Alternative 4..................................................................................................... 113

5 CUMULATIVE IMPACTS.................................................................................... 114

5.1 Cumulative Impacts Methodology................................................................... 115

5.2 Geographic Boundaries for the Analysis of Cumulative Effects..................... 115

5.3 Management Practices Considered in the Analysis of Cumulative Impacts.... 115

5.4 Risk Assessments Used for the Analysis of Cumulative Impacts.................... 115

5.5 Magnitude of Potential Impacts on Resources................................................. 116

5.6 Assumptions..................................................................................................... 117

5.7 Preferred Alternative ........................................................................................ 118

5.7.1 Socioeconomic and Human Health Factors.............................................. 118

5.7.2 Biological Resources ................................................................................ 134

5.7.3 Natural Resources..................................................................................... 144

5.8 Alternative 3..................................................................................................... 146

5.8.1 Socioeconomic and Human Health........................................................... 146

5.8.2 Biological Resources ................................................................................ 146

5.8.3 Natural Resources..................................................................................... 146

5.9 Alternative 4..................................................................................................... 147

5.9.1 Socioeconomic and Human Health........................................................... 147

5.9.2 Biological Resources ................................................................................ 147

5.9.3 Natural Resources..................................................................................... 147

6 OTHER IMPACTS AND MITIGATION MEASURES........................................ 149

6.1 Unavoidable Impacts........................................................................................ 149

6.2 Short Term Versus Long Term Effects............................................................ 149

6.3 Irreversible Resource Commitments................................................................ 149

6.4 Mitigation Measures......................................................................................... 150

7 THREATENED AND ENDANGERED SPECIES ............................................... 153

7.1 Potential Effects of DAS-40278-9 Corn on TES and Critical Habitat............. 155

7.1.1 Threatened and Endangered Plant Species and Critical Habitat............... 155

7.1.2 Threatened and Endangered Animal Species ........................................... 156

7.1.3 Summary................................................................................................... 157

7.2 Potential Effects of DAS-68416-4 Soybean and DAS-444406-06 Soybean on TES and 

Critical Habitat................................................................................................. 158

xv
7.2.1 Threatened and Endangered Plant Species and Critical Habitat............... 158

7.2.2 Threatened and Endangered Animal Species ........................................... 159

7.2.3 Summary................................................................................................... 160

8 CONSIDERATION OF EXECUTIVE ORDERS, STANDARDS, AND TREATIES 

RELATING TO ENVIRONMENTAL IMPACTS ............................................... 162

8.1 Executive Orders with Domestic Implications................................................. 162

8.2 International Implications ................................................................................ 165

8.3 Compliance with Clean Water Act and Clean Air Act .................................... 167

8.4 Impacts on Unique Characteristics of Geographic Areas ................................ 167

8.5 National Historic Preservation Act (NHPA) of 1966 as Amended.................. 169

9 LIST OF PREPARERS........................................................................................... 170

10 DISTRIBUTION LIST FOR 2,4-D EIS ................................................................. 174

11 BIBILOGRAPHY................................................................................................... 176

12 INDEX .................................................................................................................... 202

Appendix 1: USDA Notifications and States Approved for Environmental Releases of DAS40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean

Appendix 2: Summary of Public Comments on the Petitions, draft EAs, and EIS Notice of Intent

Appendix 3: Weed Management and Herbicide Use

Appendix 4: Herbicide Use Trends and Predicted Use on EnlistTM Corn and Soybean

Appendix 5: Common Weeds in Corn and Soybean

Appendix 6: Herbicide Resistance

Appendix 7: Off-Target Pesticide Movement

Appendix 8: EPA Assessments of Herbicides used on DAS Corn and Soybean

Appendix 9: Response to Comments on the DEIS

xvi
Table of Figures

Figure 1. Major Corn and Soybean Cultivation Regions in the U.S............................................. 26

Figure 2. Corn Cultivation in the 48 Conterminous U.S. ............................................................. 27

Figure 3. Soybean Cultivation in the Conterminous U.S. ............................................................ 28

Figure 4. Ecoregions of the Conterminous U.S. ........................................................................... 29

Figure 5. Locations of Excessively Eroding U.S. Croplands ....................................................... 37

Figure 6. U.S. Irrigated Acreage, 2007......................................................................................... 39

Figure 7. Acres of Corn and Soybean Planted in the U.S. 1990-2013 ......................................... 58

Figure 8. U.S. Domestic Corn Use ............................................................................................... 60

Figure 9. Corn and Soybean Price per Bushel .............................................................................. 61

Figure 10. Cropping Patterns for Major Crops............................................................................. 68

Figure 11. Percent Adoption of GE Herbicide-Resistant Corn and Soybean in the U.S.............. 71

Figure 12. Distribution of Glyphosate-resistant Weeds in the U.S. ............................................. 74

Figure 13. Number of Weed Species Resistant to Certain Herbicides in the U.S. by State ......... 75

Figure 14. Water Quality .............................................................................................................. 98

Figure 15. Irrigated Corn for Grain............................................................................................. 100

Figure 16. Irrigated Soybeans for Beans..................................................................................... 101

Table of Tables

Table 1. Summary of Issues and of Potential Impacts of the Alternatives................................... 15

Table 2. Location and Relative Distribution of Corn/Soybean Cultivation.................................. 30

Table 3. Affected Environment: Dominant and Major Secondary Soil Types by Region ........... 34

Table 4. Comparison of NLCD 2006 Land Cover Groups to Classes Used in This EIS ............. 44

Table 5. Land Cover Composition by Region .............................................................................. 46

Table 6. Major Cultivated Crops by Region in 2012.................................................................... 49

Table 7. Tillage Practices by Crop................................................................................................ 66

Table 8. Total Farm Diesel Fuel Consumption Estimate............................................................ 103

Table 9. Current Approval Status (as of July 8, 2014) of DAS-40278-9 Corn, DAS-68416-4 

Soybean, and DAS-44406-6 Soybean in Various Countries...................................................... 107

Table 10. Percent of Regional Cropland Devoted to Corn/Soybean or 2,4-D Utilizing Crops in 

Each EcoRegion.......................................................................................................................... 124

Table 11. Post-emergence Broadleaf Herbicides Commonly Used in Pastures and Rangeland 125

xvii
Table 12. Post-emergence Broadleaf Herbicides Currently Available for Use in Wheat, Barley, 

Oats, and Rye .............................................................................................................................. 127

Table 13. Fallow and Burndown Herbicides Available for Use on Selected Crops................... 129

Table 14. Post-emergence Broadleaf Herbicides Currently Available for Use on Sorghum ..... 130

Table 15. Post-emergence Broadleaf Herbicides Currently Available for Use in Rice Production

..................................................................................................................................................... 131

Table 16. Auxin-Resistant Weeds............................................................................................... 141

Table 17. DAS Corn and Soybean Lines.................................................................................... 155

xviii
ACRONYMS and ABBREVIATIONS

2,4-D 2,4-dichlorophenoxyacetic acid

2,4-DB 2,4-dichlorophenoxybutyric acid

2mEPSPS double mutant 5-enolpyruvylshikimate-3-phosphate synthase

AAD-1 aryloxyalkanoate dioxygenase

AAD-12 arylalkanoate dioxygenase

ACCase acetyl CoA carboxylase

ae acid equivalent

a.i. active ingredient

ALS acetolactate synthase

AOPP aryloxyphenoxypropionate

AOSCA American Organization of Seed Certifying Agencies

APHIS Animal and Plant Health Inspection Service (USDA)

ARMS Agricultural Resource Management Survey

ARS Agricultural Research Service (USDA)

BMPs best management practices

BNF biotechnology notification file

BRS Biotechnology Regulatory Services (USDA)

CAA Clean Air Act

CEC Canada-Mexico-U.S. Commission for Environmental Cooperation

CEQ Council on Environmental Quality 

CH4 methane

CO carbon monoxide

CO2 carbon dioxide

CRP Conservation Reserve Program

CWA Clean Water Act

DAS Dow AgroSciences

DEIS Draft Environmental Impact Statement

DMA dimethylamine

DNA deoxyribonucleic acid

DT50 dissipation time needed for herbicide to degrade to half of its original 

concentration

EA Environmental Assessment

EIS Environmental Impact Statement

EPA U.S. Environmental Protection Agency

EPSPS 5-enolpyruvylshikimate-3-phosphate synthase

ERS Economic Research Service (USDA)

ESA Endangered Species Act

EO Executive Order

FAO Food and Agriculture Organization of the United Nations

FDA U.S. Food and Drug Administration

FEIS Final Environmental Impact Statement

FFDCA Federal Food, Drug, and Cosmetic Act

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act

xix
fl oz/A fluid ounces per acre

FQPA Food Quality Protection Act

FONSI Finding of No Significant Impact

FR Federal Register

GE genetically engineered

GHG greenhouse gases

GMO genetically modified organism

GR glyphosate resistant

GT glyphosate tolerant

HPPD 4-hydroxyphenylpyruvate dioxygenase

HR herbicide resistant

HRAC Herbicide Resistance Action Committee 

IPCC Intergovernmental Panel on Climate Change

IPM Integrated Pest Management

IPPC International Plant Protection Convention

ISPM International Standard for Phytosanitary Measure

lb ae pounds acid equivalent

lb ai pounds active ingredient

LMO living modified organism

MOU memorandum of understanding

MCPA (4-chloro-2-methylphenoxy) acetic acid/2-Methyl-4-chlorophenoxyacetic 

acid

MSO methylated seed oil

N2O nitrous oxide

NAAQS National Ambient Air Quality Standards

NAPPO North American Plant Protection Organization

NASS National Agricultural Statistics Service (USDA)

NEPA National Environmental Policy Act

NHPA National Historic Preservation Act

NLCD National Land Cover Dataset

NMFS National Marine Fisheries Service

NO2 nitrogen dioxide

N2O nitrous oxide

NOI Notice of Intent

NPS nonpoint source

NRC National Research Council

NRCS Natural Resources Conservation Service

O3 ozone

OECD Organization for Economic Co-operation and Development

OPP Office of Pesticide Programs (EPA)

PAT phosphinothricin acetyltransferase

Pb lead

PCR polymerase chain reaction

PM particulate matter

PM2.5 particulate matter with aerodynamic diameter of 2.5 micrometer or less

xx
PM10 particulate matter with aerodynamic diameter of 10 micrometer or less 

PPA Plant Protection Act

PPO protoporphyrinogen oxidase

PPRA plant pest risk assessment

PRA pest risk analysis

RR Roundup ReadyTM

SO2 sulfur dioxide

SOA site of action

TES threatened and endangered species

Tg CO2 Eq teragrams of CO2 Equivalent

USDA U.S. Department of Agriculture

USFWS United States Fish and Wildlife Service

USGS United States Geological Survey

WPS worker protection standard

WSSA Weed Science Society of America

xxi
1 PURPOSE AND NEED

1.1 Introduction

Summarized as “Protecting American Agriculture,” the mission of the United States Department 

of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) is “To protect the 

health and value of American agriculture and natural resources.” 2 APHIS regulates plant and 

animal health to achieve its mission. It integrates these regulatory functions to help ensure 

beneficial impacts on United States (U.S.) domestic agricultural production, commodities, trade

in agricultural products, and the environment.

One function critical to the APHIS mission is preventing the introduction and distribution of 

plant pests. This includes the management of certain plants, animals, and microorganisms that 

harm plants and cause economic losses to U.S. agriculture. It extends to practices and 

technologies that have the potential to increase plant pest risks.

The biochemistry and molecular biology of genetic inheritance provides the framework of 

modern biotechnology. Genetic engineering is an application of biotechnology that involves the 

precise removal of selected genetic traits from organisms and insertion into other organisms. It 

enables the transfer of genes without the need for classical cross-breeding, so individual, highly 

specific, beneficial genetic traits can be moved between unrelated species.

APHIS regulates those GE organisms that have the potential to be plant pests or to increase plant 

pest risks. It performs extensive, science-based analyses to determine whether or not a GE 

organism is a plant pest. Results are recorded by the Agency in a plant pest risk assessment 

(PPRA). If the conclusion of the PPRA is that a GE organism is unlikely to be a plant pest, the 

Agency conducts an environmental review consistent with regulations codified under authority 

of the National Environmental Policy Act (NEPA) before making a formal determination about 

its regulatory status.

1.2 APHIS Regulatory Authority

The Plant Protection Act of 2000 (PPA) as amended (7 U.S.C. §§ 7701–7772) provides APHIS 

with legal authorization to implement its mission. Regulations promulgated for this enabling 

legislation are codified in Title 7, part 340, of the U.S. Code of Federal Regulations (7 CFR part 

340). The defining mandate of the PPA is authorization for APHIS to regulate, manage and 

control plant pests.

2

For more details about the APHIS mission, visit http://www.aphis.usda.gov/about_aphis/

1

 
1.2.1 Context for This FEIS

Pursuant to its PPA authority, as implemented in 7 CFR part 340, APHIS must respond to a 

petition to reclassify a regulated article as not subject to regulation under the plant pest

provisions of the PPA. APHIS, as a Federal agency, must also comply with applicable U.S.

environmental laws and regulations, such as NEPA, prior to a decision on a petition.

This final environmental impact statement (FEIS) is prepared pursuant to the NEPA process for 

the three petitions submitted by Dow AgroSciences (Dow), LLC, Indianapolis, Indiana. These

petitions seek determinations of nonregulated status for GE corn and soybean cultivars 

engineered for resistance3 to herbicides. Each petition identifies a different variety. In each, Dow

presents data supporting the claim the variety does not represent a plant pest risk and should not 

be regulated by APHIS under the PPA and 7 CFR part 340. A brief summary of defining 

characteristics for each variety described in these petitions follows.

APHIS Petition 09-233-01p (DAS, 2010a) is for non-regulatory status designation of 

event (an event is a line produced from the insertion of a specific DNA into a plant 

species)DAS-40278-9 corn (Zea mays). It is engineered for increased resistance to certain 

broadleaf herbicides in the phenoxy auxin group such as 2,4-D (2,4-

dichlorophenoxyacetic acid). DAS-40278-9 corn is also resistant to grass herbicides 

classified as aryloxyphenoxypropionate (AOPP) acetyl coenzyme A carboxylase 

(ACCase) inhibitors, such as quizalofop-p-ethyl (quizalofop), that are referred to as fop 

herbicides.

APHIS Petition 09-349-01p (DAS, 2010b) is for non-regulatory status designation of 

event DAS-68416-4 soybean (Glycine max). It is engineered for increased resistance to

2,4-D and the nonselective herbicide, glufosinate ammonium (glufosinate).

APHIS Petition Number 11-234-01p (DAS, 2011a) is for non-regulatory status 

designation of event DAS-44406-6 soybean, which is genetically engineered for 

increased resistance to certain broadleaf herbicides, including the nonselective herbicides 

glufosinate, glyphosate, and those in the phenoxy auxin group such as 2,4-D.

3

Resistance to herbicides is defined by the Herbicide Resistance Action Committee (HRAC) as the inherited ability 

of a plant population to survive and reproduce following repeated exposure to a dose of herbicide normally lethal to 

the wild type HRAC (2013) Guideline to the management of herbicide resistance, Vol. 2013: Herbicide Resistance 

Action Committee. Resistance may be induced by genetic engineering or selection of variants produced by tissue 

culture or mutagenesis ibid. This is distinguished from tolerant, which is defined by HRAC as the inherent ability of 

a plant to survive and reproduce after herbicide treatment. This implies that there was no selection or genetic 

manipulation to make the plant tolerant; it is naturally tolerant ibid. Developers may use these terms differently. 

“Herbicide-Tolerant” is a term used by the petitioner to be synonymous with “herbicide resistant” as it is used in this 

FEIS.

2

 
All of the varieties described here are currently regulated under 7 CFR part 340. Interstate 

movement and field trials of each (DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-

6 soybean) were conducted under permits issued or notifications acknowledged by APHIS since 

2006, 2008, and 2009, respectively. The field trials were conducted within selected growing 

areas in the U.S. (see Appendix 1 for a list of notifications and states approved for environmental 

releases for each of the petitions). Data from field trials are reported in the petitions (DAS, 

2010a; b; 2011a) and were analyzed in separate PPRAs prepared by APHIS (USDA-APHIS, 

2010b; 2012a; b) for each event (i.e., DAS-40278-9 corn, DAS-68416-4 soybean, and DAS44406-6 soybean).

If APHIS makes a determination of nonregulated status for each of these GE varieties, they will 

cease to be subject to the PPA and 7 CFR part 340. If they are not regulated, crosses between 

them and conventional, non-GE varieties will not be regulated either, nor will crosses between 

them and other biotechnology-derived varieties that have been classified previously by APHIS as 

not subject to regulation as plant pests under the PPA and 7 CFR part 340.

1.3 Purpose of These Products

Dow has developed HR (herbicide-resistant) DAS-40278-9 corn, DAS-68416-4 soybean, and 

DAS-44406-6 soybean as alternatives to currently available GE HR corn and soybean varieties

(DAS, 2010a; b; 2011a). Most GE HR crops in the U.S. have historically included only a 

glyphosate-resistant (GR) trait. This situation has limited the diversity of herbicides used for 

weed management and resulted in intense reliance on glyphosate. This trend has been 

accompanied by a corresponding increase in glyphosate resistance in some weeds in corn and 

soybean production systems (USDA-APHIS, 2012b). The new corn and soybean varieties

developed by Dow (DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean) 

provide for greater flexibility in the choices growers have when selecting herbicides to control 

troublesome weeds. The availability of these varieties should diversify weed control and 

resistance management strategies. Additional details about each of these new varieties are 

summarized in the following subsections.

1.3.1 DAS-40278-9 Corn

DAS-40278-9 corn was genetically engineered to express the aryloxyalkanoate dioxygenase

(AAD-1) protein. The aad-1 gene encodes the AAD-1 protein which provides the plant with

increased resistance to treatment with phenoxy auxin herbicides and AOPP ACCase inhibitors. 

The most well-known and widely-used phenoxy auxin herbicide is 2,4-D, which has been used 

for many decades as a pre-plant or post-emergent herbicide to control dicotyledonous (dicot or 

broadleaf) weeds in cornfields.

AOPP ACCase inhibitors, or “fop” herbicides, are post-emergent graminicides. They provide 

selective, post-emergent control of monocotyledonous (monocot) weed species in the grass 

family (Poaceae). Since corn is a poaceous monocot species, it is sensitive to treatment with 

“fop” herbicides. Therefore, these herbicides typically are not labeled for corn, so cannot be used 

for weed control in cornfields.

3
If no longer subject to the regulatory requirements of 7 CFR part 340 and the PPA, Dow intends 

to make DAS-40278-9 corn commercially available as the first corn variety with increased 

resistance to 2,4-D. Dow has announced its plans to market DAS-40278-9 corn hybrids stacked 

with a GR trait that will be marketed under the name EnlistTM corn.

1.3.2 DAS-68416-4 and DAS-44406-6 Soybean

DAS-68416-4 soybean is genetically engineered to express the arylalkanoate dioxygenase 

(AAD-12) protein and the phosphinothricin acetyltransferase (PAT) protein. The aad-12 gene 

encodes the AAD-12 protein which provides the plant with increased resistance to several 

aryloxyalkanoate-based herbicides, including 2,4-D, MCPA (4-chloro-2-methylphenoxyacetic 

acid), and 2,4-DB (2,4-dichlorophenoxybutyric acid). It also conveys resistance to pyridyl

oxyacetate herbicides, such as triclopyr and fluroxypyr (DAS, 2010b).

The pat gene encodes the PAT protein that inactivates the herbicide glufosinate (DAS, 2010b). If 

APHIS determines that these varieties are not subject to the regulatory requirements of the PPA 

and 7 CFR part 340, DAS intends to make DAS-68416-4 soybean commercially available as the 

first soybean variety with resistance to 2,4-D.

As its counterpart described above (DAS-68416-4 soybean), DAS-44406-6 soybean has been

genetically engineered to express the AAD-12 and the PAT proteins to confer resistance to the 

herbicides 2,4-D and glufosinate. In addition, the double mutant 5-enolpyruvylshikimate-3-

phosphate synthase (2mEPSPS) gene has been incorporated in DAS-44406-6 soybean via 

genetic engineering. It encodes the 2mEPSPS protein. This results in a soybean plant with 

decreased sensitivity to the herbicide glyphosate (DAS, 2011a).

DAS has indicated its intention to stack glyphosate resistance into DAS-68416-4 lines by 

conventional breeding to a previously deregulated soybean event with glyphosate 

resistance(DAS, 2010b). It is expected that soybean lines containing either event DAS-68416-4 

or DAS-44406-6 will be resistant to the same three herbicides: 2,4-D, glufosinate, and 

glyphosate. The only difference between these two soybean events is that resistance to 

glyphosate in DAS-68416-4 soybean will be achieved by traditional breeding with another 

soybean containing a glyphosate resistance trait, while DAS-44406-6 soybean has been 

genetically engineered with the 2mEPSPS gene.

1.4 Coordinated Regulatory Framework for Genetically-Engineered Organisms

The U.S. government has regulated GE organisms since 1986 under Federal regulations

published in the Federal Register (51 FR 23302; 57 FR 22984) entitled “The Coordinated 

Framework for the Regulation of Biotechnology” (henceforth referred to here as the Coordinated 

Framework). The Coordinated Framework, published by the Office of Science and Technology 

Policy, describes the comprehensive Federal regulatory policy for ensuring the safety of 

biotechnology research and products. It also explains how Federal agencies will use existing 

Federal statutes to ensure public health and environmental safety while maintaining regulatory 

flexibility to avoid impeding the growth of the biotechnology industry.

4
Three central guiding principles form the basis for the Coordinated Framework:

(1) Agencies should define those transgenic organisms subject to review to the extent 

permitted by their respective statutory authorities;

(2) Agencies are required to focus on the characteristics and risks of a biotechnology 

product, not the process by which it was created;

(3) Agencies are mandated to exercise oversight of GE organisms only when there is 

evidence of “unreasonable” risk.

The Coordinated Framework explains the regulatory roles and authorities for the three major 

agencies involved in regulating GE organisms: USDA APHIS, the Environmental Protection 

Agency (EPA), and the Food and Drug Administration (FDA). A summary of each role follows.

1.4.1 USDA-APHIS

As noted in 1.2, the PPA authorizes APHIS to regulate, manage and control plant pests. With 

regard to organisms and products altered or produced through genetic engineering which are 

plant pests or which there is reason to believe are plant pests, APHIS regulates their introduction 

(i.e., importation, interstate movement, or release into the environment). A GE organism is 

considered a regulated article if the donor organism, recipient organism, vector, or vector agent 

used in engineering the organism belongs to one of the taxa listed in the regulation (7 CFR part

340.2) and is also considered a plant pest. A GE organism is also regulated under 7 CFR part

340, when APHIS has reason to believe that the GE organism may be a plant pest or APHIS does 

not have sufficient information to determine if the GE organism is unlikely to be a plant pest 

risk. A GE organism is no longer subject to the plant pest provisions of the PPA or to the 

regulatory requirements of 7 CFR part 340, when APHIS determines that it is unlikely to pose a 

plant pest risk. 

An individual may petition the Agency for a determination that a particular regulated article is 

unlikely to be a plant pest risk, and should not be regulated under the plant pest provisions of the 

PPA and the regulations at 7 CFR part 340. Under §340.6(c)(4), the petitioner must provide 

information regarding the plant that the Agency can use to determine whether or not a regulated 

article is a plant pest risk. A GE organism or other regulated article is subject to the regulatory 

requirements of 7 CFR part 340 of the PPA until APHIS determines that it is unlikely to be a 

plant pest risk.

1.4.2 Environmental Protection Agency

The EPA is responsible for regulating the sale, distribution, and use of pesticides, including 

herbicides and those that are expressed by an organism modified using techniques of modern 

biotechnology. Such pesticides are regulated by the EPA as plant-incorporated protectants under 

the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (7 U.S.C. 136 et seq.). The 

EPA also regulates certain biological control organisms under the Toxic Substances Control Act 

(TSCA) (15 U.S.C. 53 et seq.). Before planting a crop containing a plant incorporated protectant, 

5
an individual or company must seek an experimental use permit from the EPA. Commercial 

production of crops containing plant incorporated protectants for purposes of seed increase and 

sale requires a FIFRA Section 3 registration with the EPA.

Under FIFRA (7 U.S.C. 136 et seq.), the EPA requires registration of all pesticide products for 

all specific uses prior to distribution for sale. Before granting a registration, the EPA evaluates 

the toxicity of the ingredients of a pesticide product, the particular site or crop on which it is to 

be used, the amount, frequency, and timing of its use, and storage and disposal requirements. 

Prior to registration for a new or amended use for a new or previously registered pesticide, the

EPA must determine through testing that the pesticide does not cause unreasonable adverse 

effects on humans, the environment, and non-target species, when used in accordance with label 

instructions. EPA must also approve the language used on the pesticide label in accordance with 

40 CFR part 158.

Once registered, a pesticide may only be legally used in accordance with directions and 

restrictions on its label. The purpose of the label is to minimize risks to human health and the 

environment. The Food Quality Protection Act (FQPA) of 1996, (Pub. L. No. 104 – 170, 110 

Stat. 1489) amended FIFRA, enabling the EPA to implement periodic registration review of 

pesticides to ensure they are meeting current scientific and regulatory standards of safety and 

continue to have no unreasonable adverse effects (US-EPA, 2011d). 

The EPA also sets tolerances (maximum residue levels) or establishes an exemption from the 

requirement for a tolerance, under the Federal Food, Drug, and Cosmetic Act (FFDCA). A 

tolerance is the amount of pesticide residue that can remain on or in food for human consumption 

or animal feed. Before establishing a pesticide tolerance, the EPA is required to reach a safety 

determination based on a finding of reasonable certainty of no harm under the FFDCA, as 

amended by the FQPA. The FDA enforces the pesticide tolerances set by the EPA.

1.4.3 Food and Drug Administration

The FDA regulates GE organisms under the authority of the FFDCA (21 U.S.C. 301 et seq.). The 

FDA published its policy statement concerning regulation of products derived from new plant 

varieties, including those derived from genetic engineering, on May 29, 1992 (57 FR 22984). 

Under this policy, the FDA implements a voluntary consultation process to ensure that human 

food and animal feed safety issues or other regulatory issues, such as labeling, are resolved 

before commercial distribution of food derived from GE products. This voluntary consultation 

process provides a way for developers to receive assistance from the FDA in complying with 

their obligations under Federal food safety laws prior to marketing.

In June 2006, the FDA also published recommendations in “Guidance for Industry: 

Recommendations for the Early Food Safety Evaluation of New Non-Pesticidal Proteins 

Produced by New Plant Varieties Intended for Food Use” (US-FDA, 2006). This establishes

voluntary food safety evaluations for new non-pesticidal proteins produced by new plant 

varieties intended to be used as food, including GE plants. Early food safety evaluations help 

ensure that potential food safety issues related to a new protein in a new plant variety are 

addressed early in development. These evaluations are not intended as a replacement for a 

6
biotechnology consultation with the FDA, but the information may be used later in the 

biotechnology consultation.

1.5 Purpose and Need for This APHIS Action

APHIS is required to respond, consistent with its PPA authority and regulations at 7 CFR part

340.6, to three petitions from Dow. Each petition is for a different GE HR event: DAS-40278-9 

corn, DAS-68416-4 soybean, and DAS-44406-6 soybean. In its submissions, the petitioner has 

provided information consistent with that described in §340.6(c)(4), which is required to inform 

APHIS of the full range of biological and chemical properties of the plant, so that APHIS can 

assess the plant pest risk of each of these events to determine if they are unlikely to be a greater 

plant pest risk than the unmodified organisms from which they were derived. Therefore, APHIS 

must respond to these petitions from Dow, who requests a determination of nonregulated status 

for each of these GE HR resistant plant varieties. If the Agency determines that a regulated 

article is unlikely to be a plant pest risk, a GE organism is no longer subject to the regulatory 

provisions of the PPA and the regulations of 7 CFR part 340.

Under the provisions of the National Environmental Policy Act (NEPA) as amended (42 U.S.C. 

4321 et seq.), prior to implementation, Federal agencies must examine the potential impacts of 

proposed major actions that may significantly affect the quality of the human environment. The

Agency has considered how to properly examine the potential environmental impacts of its 

decisions for petitions for determination of nonregulated status, in accordance with NEPA, 

regulations of the Council on Environmental Quality (CEQ) for implementing the procedural 

provisions of NEPA (40 CFR parts 1500-1508), USDA regulations implementing NEPA (7 CFR 

part 1 b), and the NEPA Implementing Procedures (7 CFR part 372) of APHIS.

Historically, for each petition for a determination of nonregulated status for a GE organism that 

APHIS has evaluated, the Agency has prepared an environmental assessment (EA) to provide the 

APHIS decisionmaker with a review and analysis that identifies whether there may be any 

significant environmental impacts. If the Agency makes a finding of no significant impacts

(FONSI), the NEPA process is completed and a decision is issued. If significant environmental 

impacts are identified, the agency is then required to prepare an environmental impact statement 

(EIS) before a determination is made.

APHIS has prepared draft EAs for two of the petitions, 09-233-01p (DAS-40278-9 corn) and 09-

349-01p (DAS-68416-4 soybean), that are the subject of this EIS (see subsections 1.4.2 and 1.4.3

for further information including links to the dockets). These EAs were made available for public 

comment. In reviewing petitions for determinations of nonregulated status of GE crop cultivars 

resistant to various herbicides, APHIS has identified the possible selection of HR weeds as an

environmental impact. This impact is a cumulative impact that would result from the combined 

action of USDA on the subject petitions and on the EPA’s action to register 2,4-D for use on 

DAS-40278-9 corn , DAS-68416-4 soybean or DAS-44406-6 soybean. If 2,4-D resistant weeds 

were to be selected as a result of this combined action, growers who rely on 2,4-D for effective 

and inexpensive weed control are likely to experience increased socioeconomic impacts from 

more costly weed control. Therefore, for the decisions on the three DAS petitions, APHIS has 

7
prepared this FEIS to further analyze the potential for selection of 2,4-D-resistant weeds and 

other impacts that may occur.

This EIS provides APHIS decisionmakers with a mechanism for examining the broad and 

cumulative impacts on the quality of the human environment4 that may result from 

determinations of nonregulated status of DAS-40278-9 corn, DAS-68416-4 soybean, and DAS44406-6 soybean. APHIS has included Petition 11-234-01p (DAS-44406-6 soybean) in this EIS 

analysis because this soybean variety exhibits the same or similar HR traits as DAS-68416-4 

soybean, so presents the same environmental issues. 

APHIS has prepared this EIS to consider the potentially significant environmental effects of a 

determination of nonregulated status, consistent with NEPA/CEQ regulations and USDAAPHIS-NEPA-implementing regulations and procedures (40 CFR parts 1500-1508, 7 CFR part 

1b, and 7 CFR part 372).

1.6 Public Involvement

APHIS seeks public comment on EAs and EISs prepared in response to petitions seeking a 

determination of nonregulated status of a regulated GE organism. APHIS does this through a 

notice published in the Federal Register. A notice seeking public comments on each of the three 

petitions was published in the Federal Register. Notices for two of them, 09-233-01p (DAS40278-9 corn) and 09-349-01p (DAS-68416-4 soybean), also sought comment on the draft 

PPRA and draft EA for each petition. An EA was not prepared for the third petition, 11-234-01p 

(DAS-44406-6 soybean), so that notice only sought comments for the petition. This APHIS used 

this procedure because a decision to prepare an EIS had been made for the other two petitions, 

and APHIS, in recognizing the similarity of DAS-44406-6 soybean to the other two petitions,

decided to include it as part of this EIS.

A critical issue discussed in this EIS is the potential for significant environmental impacts 

associated with increased use of herbicides, particularly 2,4-D (and the other chlorophenoxy 

herbicides to which these crops are resistant), and the risk that these herbicides could contribute 

to the development of HR weeds. These potential impacts are compared to those that currently 

occur in corn and soybean production systems. Other issues addressed include those related to 

the cultivation of corn and soybean using the various agricultural production methods currently 

practiced, and the environmental and food/feed safety of GE plants.

Issues analyzed in this EIS were identified by considering public comments submitted (1) during 

the scoping periods for this EIS; (2) for the draft EIS; (3) for the draft EAs prepared for two of 

the petitions (09-233-01p and 09-349-01p); (4) for the petitions for all three events that are the 

4 Under NEPA regulations, the “human environment” includes “the natural and physical environment and the 

relationship of people with that environment” (40 CFR §1508.14).

8

 
subject of this EIS (i.e., DAS-68416-4 soybean; DAS-44406-6 soybean; DAS-40278-9 corn); (5) 

for other EAs previously prepared by APHIS for GE organisms. These issues were analyzed to 

assess the potential environmental impacts of DAS-40278-9 corn, DAS-68416-4 soybean, and 

DAS-44406-6 soybean, should they be granted nonregulated status by USDA APHIS. These 

comments are summarized in Appendix 2 (draft EAs and EIS Notice of Intent) and Appendix 9 

(draft EIS).

1.6.1 EIS Scoping: Public Comment Period 

APHIS sought comments for the scoping of this EIS in an announcement that was published at 

http://www.regulations.gov/#!docketDetail;D=APHIS-2013-0042. Its availability was announced 

in a May 16, 2013 Federal Register notice that closed July 17, 2013. In addition, APHIS held 

two virtual public meetings on June 26, 2013 and June 27, 2013. For comments received during 

the scoping period see Appendix 2.

1.6.2 Public Comment Period for Draft EIS

APHIS thereafter issued the draft environmental impact statement (DEIS) for the petitions for a 

determination of nonregulated status for DAS-40278-9 corn, DAS-68416-4 soybean, and DAS44406-6 soybean, and sought public comment on the DEIS through publication of a Notice of 

Availability (NOA) for the DEIS in the Federal Register on Jan 10, 2014 (79 FR 1861). The 

NOA explained how interested agencies, organizations, and individuals could access the DEIS 

for review and comment. The NOA also explained the process for submitting comments on the 

DEIS to APHIS. The DEIS was available for public comment for 60 days. APHIS also held a 

virtual public meeting on the DEIS on January 29, 2014. At the end of the 60-day comment 

period (Mar 11, 2014), APHIS analyzed and considered comments in preparing this FEIS. There 

was substantive information provided in public comments that was considered in the analysis for 

this FEIS. Our Response to Comments that we have prepared in order to address all the 

comments received in reference to the DEIS is in Appendix 9.

1.6.3 Public Comment Period for Draft EA for Petition 09-233-01p 

APHIS published Petition 09-233-01p from Dow, the draft PPRA and the draft EA on December 

27, 2011, for a 120-day comment period that closed April 27, 2012. The docket file is published 

at http://www.regulations.gov/#!docketDetail;D=APHIS-2010-0103

Most of the substantive comments (summarized in Appendix 2) on the docket were related to the 

herbicide use on the plant, including increased herbicide use, related health and environmental 

effects and further development of HR weeds.

1.6.4 Public Comment Period Draft EA for Petition 09-349-01p 

APHIS published the petition, draft EA, and draft PPRA on July 11, 2012, for a 60-day public 

comment period that closed on September 11, 2012 (see Appendix 2 for a summary of 

comments). The docket file is published at: 

http://www.regulations.gov/#!docketDetail;D=APHIS-2012-0019

9
1.6.5 Public Comment Period for Petition 11-234-01p 

APHIS published Petition 11-234-01p (DAS-44406-6 soybean) on July 11, 2012, for a 60-day 

public comment period that closed on September 11, 2012. The docket file is published at 

http://www.regulations.gov/#!docketDetail;D=APHIS-2012-0032. As of that date, the docket file 

contained a total of 291 docket records, reflecting a total 68,462 public comments. The issues 

identified in the public comments related to DAS-44406-6 soybean are summarized in Appendix 

2.

1.7 Issues Considered

The list of resource areas considered in this EIS were identified in part by APHIS from public 

comments (summarized in Appendix 2) received for the petitions and EAs considered in this 

EIS, the Notice of Intent, and virtual stakeholder meetings . Relevant concerns and issues cited in 

comments submitted by the public and various stakeholders in response to previous petitions and 

EAs for GE organisms also contributed to this process, as did concerns identified in previous 

unrelated lawsuits. The following list includes the resource areas considered in this EIS:

• Land Use

• Domestic Use of Corn and Soybeans

• Export of Corn and Soybean

• Food and Feed Safety

• Worker Safety

• Animal and Plant Communities

• Biodiversity

• Soil Quality

• Water Quality

• Air Quality

• Climate Change

10
2 ALTERNATIVES

This FEIS analyzes the potential environmental consequences of a determination of nonregulated 

status of DAS-68416-4 and DAS-44406-6 soybean, and DAS-40278-9 corn. In responding to the 

petitions, APHIS must determine whether DAS-68416-4soybean, DAS 44406-6 soybean, and 

DAS-40278-9 corn are unlikely to pose plant pest risks. Based on its PPRAs (USDA-APHIS, 

2010b; 2012a; b), APHIS has concluded that DAS-68416-4 soybean, DAS-44406-6 soybean, and 

DAS-40278-9 corn are unlikely to pose plant pest risks. 

APHIS evaluated four alternatives in this EIS: (1) No Action Alternative; (2) determination of 

nonregulated status of DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 corn

(Preferred Alternative); (3) determination of nonregulated status of DAS-40278-9 corn, only; (4) 

determination of nonregulated status of DAS-68416-4 soybean and DAS-44406-6 soybean, only. 

APHIS has assessed the potential for environmental impacts for each alternative in the Potential 

Environmental Consequences section.

2.1 Alternative 1: No-Action Alternative—Continuation as Regulated Articles

Under the No Action Alternative, APHIS would deny the three petitions (DAS, 2010a; b; 

2011a). DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 corn and progeny 

derived from these event lines would continue to be regulated articles under the regulations at 7 

CFR part 340. APHIS would still require permits or notifications for their introduction, and

would continue to implement measures to ensure physical and reproductive confinement. APHIS 

could choose this alternative if there were insufficient data for APHIS to completely evaluate the

potential plant pest risks associated with the unconfined cultivation of DAS-68416-4 soybean,

DAS-44406-6 soybean, and DAS-40278-9 corn.

This alternative is not the Preferred Alternative because APHIS evaluated the data and concluded 

in its PPRAs that DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 corn are 

unlikely to be plant pest risks (USDA-APHIS, 2010b; 2012a; b). Therefore, choosing this 

alternative would be inconsistent with the purpose and need of the project because it is 

inconsistent with the scientific evidence before APHIS regarding plant pest risk. 

2.2 Alternative 2: Determination of Nonregulated Status of DAS-68416-4 Soybean,

DAS 44406-6 Soybean, and DAS-40278-9 Corn (Preferred Alternative)

Under this alternative, DAS-68416-4 soybean, DAS 44406-6 soybean, and DAS-40278-9 corn 

and progeny derived from their cultivation would no longer be subject to APHIS biotechnology

regulations. APHIS would no longer require permits or notifications for introductions of these 

varieties because they are unlikely to pose plant pest risks (USDA-APHIS, 2010b; 2012a; b). 

This is the Preferred Alternative because a determination of nonregulated status for all three 

varieties, DAS-68416-4 soybean, DAS 44406-6 soybean, and DAS-40278-9 corn, would be 

consistent with the plant pest provisions of the PPA, the regulations codified in 7 CFR part 340, 

and the biotechnology regulatory policies in the Coordinated Framework.

11
2.3 Alternative 3: Determination of Nonregulated Status of DAS-40278-9 Corn Only 

Under this alternative, only DAS-40278-9 corn and progeny derived from its cultivation would 

no longer be subject to regulations. DAS-68416-4 and DAS-44406-6 soybean would continue to 

be regulated as described under Alternative 1. APHIS would no longer require permits or 

notifications for introductions of DAS-40278-9 corn and progeny derived from this event

because it is unlikely to pose a plant pest risk (USDA-APHIS, 2010b). APHIS could choose this 

alternative if data were not sufficient to complete an evaluation of potential plant pest risks

associated with the unconfined cultivation of DAS-68416-4 soybean and DAS-44406-6 soybean. 

However, APHIS made the determination that these varieties are not likely to be plant pests

(USDA-APHIS, 2012a; b) as part of the PPRA process. Therefore, choosing this alternative

would be inconsistent with the purpose and need of the project because it is inconsistent with the 

scientific evidence before APHIS regarding plant pest risk.

2.4 Alternative 4: Determination of Nonregulated Status of DAS-68416-4 Soybean and 

DAS 44406-6 Soybean Only 

Under this alternative, only DAS-68416-4 soybean and DAS 44406-6 soybean, and progeny 

derived from their cultivation would no longer be subject to regulations. APHIS would no longer 

require permits or notifications for introductions of DAS-68416-4 soybean and DAS 44406-6 

soybean and progeny derived from these varieties because it is unlikely that they pose a plant 

pest risk (USDA-APHIS, 2012a; b). APHIS could choose this alternative if there was insufficient 

evidence to demonstrate the lack of plant pest risk from the unconfined cultivation of DAS40278-9 corn. However, APHIS made the determination that this variety is unlikely to be a plant 

pest (USDA-APHIS, 2010b) as part of the PPRA process. Therefore, choosing this alternative

would be inconsistent with the purpose and need of the project because it is inconsistent with the 

scientific evidence before APHIS regarding plant pest risk.

2.5 Alternatives Considered but Rejected from Further Consideration

APHIS assembled a list of alternatives considered for DAS-68416-4 soybean, DAS 44406-6 

soybean, and DAS-40278-9 corn. The Agency evaluated these Alternatives in accordance with 

its authority under the plant pest provisions of the PPA, and the regulations at 7 CFR part 340. In 

this evaluation APHIS considered environmental safety, efficacy, and practicality to identify 

which alternatives the Agency would further consider for DAS-68416-4 soybean, DAS 44406-6 

soybean, and DAS-40278-9 corn. Based on this evaluation, APHIS rejected several alternatives. 

These alternatives are described briefly below along with the specific reasons for rejecting each.

2.5.1 Prohibit Any DAS-68416-4 Soybean, DAS-44406-6 Soybean, and DAS-40278-9 

Corn from Being Released

In response to public comments that stated a preference that no GE organisms enter the 

marketplace, APHIS considered prohibiting the release of DAS-68416-4 soybean, DAS 44406-6 

soybean, and DAS-40278-9 corn, including denial of any permits associated with field testing. 

APHIS determined that this alternative is not appropriate because APHIS has concluded that 

DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 corn are unlikely to be plant 

12
pest risks (USDA-APHIS, 2010b; 2012a; b). Therefore, choosing this alternative would be 

inconsistent with the purpose and need of the project because it is inconsistent with the scientific 

evidence before APHIS regarding plant pest risk.

In enacting the PPA, Congress included findings in Section 402(4) that: “decisions affecting 

imports, exports, and interstate movement of products regulated under this title [i.e., the PPA] 

shall be based on sound science.”

On March 11, 2011, in a Memorandum for the Heads of Executive Departments and Agencies, 

the White House Emerging Technologies Interagency Policy Coordination Committee 

established principles consistent with Executive Order 13563 to guide agencies in the 

development and implementation of policies for oversight of emerging technologies such as GE 

that included the following guidance: 

“Decisions should be based on the best reasonably obtainable scientific, technical, 

economic, and other information, within the boundaries of the authorities and mandates 

of each agency.” 

Consistent with this guidance and based on the findings and scientific data evaluated for the 

PPRAs (USDA-APHIS, 2010b; 2012a; b), APHIS concluded that DAS-68416-4 soybean, DAS44406-6 soybean, and DAS-40278-9 corn are unlikely to pose a plant pest risk. Therefore, there 

is no basis in science for prohibiting the release of these varieties.

2.5.2 Approve the Petition(s) in Part

The regulations at 7 CFR part 340.6(d)(3)(i) state that APHIS may “approve the petition in 

whole or in part.” However, APHIS has concluded that DAS-68416-4 soybean, DAS-44406-6 

soybean, and DAS-40278-9 corn are unlikely to pose any plant pest risks (USDA-APHIS, 

2010b; 2012a; b), so there is no regulatory basis under the plant pest provisions of the PPA for 

granting only partial approval of any of the petitions. Therefore, an approval in part would be 

inconsistent with the purpose and need of the project because it is inconsistent with the scientific 

evidence before APHIS regarding plant pest risk.

2.5.3 Production/Geographical Restrictions to Isolate DAS-68416-4 Soybean, DAS44406-6 Soybean, and DAS-40278-9 Corn from Non-GE Soybean or Corn

In response to public concerns of gene movement between GE and non-GE plants, APHIS 

considered requiring isolation distances separating DAS-68416-4 soybean, DAS-44406-6 

soybean, and DAS-40278-9 corn from non-GE soybean or corn production. However, because 

APHIS has concluded that DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 

corn are unlikely to pose plant pest risks (USDA-APHIS, 2010b; 2012a; b), an alternative based 

on requiring isolation distances would be inconsistent with the Agency’s statutory authority 

under the plant pest provisions of the PPA and regulations in 7 CFR part 340 because it is 

inconsistent with the scientific evidence before APHIS regarding plant pest risk. 

13
APHIS also considered geographically restricting the production of DAS-68416-4 soybean,

DAS-44406-6 soybean, and DAS-40278-9 corn based on the location of organic production

systems of non-GE soybean and corn or production systems for GE-sensitive markets in 

response to public concerns regarding possible gene movement between GE and non-GE plants. 

However, as presented in the APHIS plant pest risk assessments (USDA-APHIS, 2010b; 2012a; 

b), there are no geographic differences associated with any identifiable plant pest risks for DAS68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 corn. This alternative was not 

analyzed in detail because APHIS has concluded that DAS-68416-4 soybean, DAS-44406-6 

soybean, and DAS-40278-9 corn do not pose plant pest risks, and will not exhibit a greater plant 

pest risk in any geographically restricted area (USDA-APHIS, 2010b; 2012a; b). Therefore, 

such an alternative would be inconsistent with the APHIS statutory authority under the plant pest 

provisions of the PPA and regulations in 7 CFR part 340 and the biotechnology regulatory 

policies of the Coordinated Framework because it is inconsistent with the scientific evidence 

before APHIS regarding plant pest risk.

Based on the foregoing considerations, the imposition of isolation distances or geographic 

restrictions would not meet the APHIS purpose and need to respond appropriately to petitions for 

nonregulated status as set forth in the requirements in 7 CFR part 340 and the Agency’s authority 

under the plant pest provisions of the PPA. Individuals might choose on their own to 

geographically isolate their non-GE corn or soybean production systems from DAS-68416-4

soybean, DAS-44406-6 soybean, and DAS-40278-9 corn, or to use isolation distances and other 

management practices to minimize gene movement between corn and soybean fields. 

Information to assist growers in making informed management decisions for DAS-68416-4

soybean, DAS-44406-6 soybean, and DAS-40278-9 corn is available from the American 

Organization of Seed Certifying Agencies (AOSCA, 2010).

2.5.4 Requirement of Testing for DAS-68416-4 Soybean, DAS-44406-6 Soybean, and 

DAS-40278-9 Corn

During the comment periods for other petitions for nonregulated status, some commenters 

requested that USDA require and provide testing for GE products in non-GE production systems. 

However, because DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 corn are 

unlikely to pose plant pest risks (USDA-APHIS, 2010b; 2012a; b), testing requirements are 

inconsistent with the plant pest provisions of the PPA, the regulations at 7 CFR part 340 and the 

biotechnology regulatory policies of the Coordinated Framework. Therefore, for DAS-68416-4

soybean, DAS-44406-6 soybean, and DAS-40278-9 corn, a requirement for testing would not be 

appropriate for the purpose and need of the project and APHIS’s compliance with its regulatory 

authorities. 

2.6 Comparison of Alternatives 

Table 1 includes a summary of the potential environmental consequences associated with 

selection of any of the Alternatives evaluated in this EIS. The potential environmental 

consequences assessment is presented in Chapter 4 of this EIS. The cumulative impacts are 

presented in Chapter 5.

14
Table 1. Summary of Issues and of Potential Impacts of the Alternatives

Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

Meets Purpose 

and Need

No Yes No No

Socioeconomic and Human Health

Land Use The demand for corn 

production under the No 

Action Alternative is 

expected to mirror the 

most recent USDA 

projections which predict 

a decline from 97 million 

acres to just under 92 

million acres in 2014 and 

a further decline to 88.5 

million acres through 

2023 (USDA-OCE, 

2014). The decrease in 

overall corn acres is 

expected to come as a 

result of increases in 

soybean, cotton, rice, and 

about 2.8 million less 

planted acres of field 

crops overall. (USDAOCE, 2014)The most 

recent USDA projections 

are for soybean plantings 

to increase somewhat 

Unchanged from No 

Action, although DAS68416-4 soybean, DAS44406-6 soybean, and 

DAS-40278-9 corn might 

be expected to replace 

other varieties of HR 

soybean or corn currently 

grown in the U.S., the 

acreage and location of 

production under the 

Preferred Alternative is 

expected to be the same 

as for the No Action 

Alternative.

Pressure to convert 

agricultural grasslands to 

crop production is

expected to be less based 

on about 2.8 million less 

planted acres of field 

crops overall (USDAOCE, 2014).

Unchanged from No 

Action, although DAS40278-9 corn is expected 

to replace other varieties 

of HR corn currently 

grown in the U.S., the 

acreage and location of 

corn production under 

Alternative 3 would be 

the same as for the No 

Action Alternative

Pressure to convert 

agricultural grasslands to 

crop production is

expected to be less based 

on about 2.8 million less 

planted acres of field 

crops overall (USDAOCE, 2014).

Unchanged from No 

Action, although DAS68416-4 and DAS 44406-

6 soybean might be 

expected to replace other 

varieties of HR soybean 

currently grown in the 

U.S., the acreage and 

location of soybean 

production under 

Alternative 4 would be 

the same as for the No 

Action Alternative.

Pressure to convert 

agricultural grasslands to 

crop production is

expected to be less based 

on about 2.8 million less 

planted acres of field 

crops overall (USDAOCE, 2014).

15
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

through 2020 (USDAOCE, 2014). Locations of 

corn and soybean 

production are not 

expected to change. 

Pressure to convert 

agricultural grasslands to 

crop production are 

expected to be less based on 

about 2.8 million less 

planted acres of field crops 

overall (USDA-OCE, 

2014).

16
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

Agronomic 

Practices

GR weed problems will 

continue to increase. This 

will likely force growers to 

use additional herbicides 

to control weeds, and/or 

abandon conservation 

tillage practices for more 

aggressive conventional 

tillage systems to maintain 

soybean/corn yields. 

Growers of cereal crops 

often rely on 2,4-D for 

inexpensive and effective 

weed control. Relatively 

few weeds have developed 

resistance to 2,4-D.

Enlist-DuoTM, a mix of a 

2,4-D choline formulation 

together with glyphosate 

may replace glyphosate 

for post-emergent 2,4-D 

applications in EnlistTM

corn and soybean 

cropping systems 

contingent on EPA’s 

decision to label the 

herbicide for this use. 

More efficient weed 

control is expected to 

reduce the need for more 

aggressive tillage. 

Under the Preferred 

Alternative, 2,4-D use 

and the selection pressure 

for 2,4-D resistant weeds 

is expected to increase. If 

2,4-D resistant weeds 

become prevalent, 

growers who rely on 2,4-

D for weed control are 

expected to adopt more 

costly alternative weed 

control measures.

Enlist-DuoTM, a mix of a 

2,4-D choline formulation 

together with glyphosate 

may replace glyphosate 

for post-emergent 2,4-D 

applications in EnlistTM

corn cropping systems 

contingent on EPA’s 

decision to label the 

herbicide for this use. No 

change is expected from 

the No-Action Alternative 

for current GE-soybean 

cropping systems. 

Under Alternative 3, 2,4-

D use and the selection 

pressure for 2,4-D 

resistant weeds is 

expected to increase. If 

2,4-D resistant weeds 

become prevalent, 

growers who rely on 2,4-

D for weed control are 

expected to adopt more

costly alternative weed 

control measures.

Enlist-DuoTM, a mix of a 

2,4-D together with 

glyphosate may replace 

glyphosate for postemergent 2,4-D 

applications in EnlistTM

soybean cropping 

systems contingent on 

EPA’s decision to label 

the herbicide for this use. 

More efficient weed 

control is expected to 

reduce the need for more 

aggressive tillage in 

soybean cropping 

systems. Under 

Alternative 4, 2,4-D use 

and the selection pressure 

for 2,4-D resistant weeds 

is expected to increase. If 

2,4-D resistant weeds 

become prevalent, 

growers who rely on 2,4-

D for weed control are 

expected to adopt more 

costly alternative weed 

control measures.

17
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

Trade Corn is the dominant feed 

grain traded internationally 

(USDA-OCE, 2011b). In 

2010/11, the U.S. produced 

38 percent of the total 

world supply of corn 

(USDA-OCE, 2011b). 

Primary importers of corn 

from the U.S. include 

Japan, Mexico, Korea, 

Egypt, Taiwan, Syria, the 

EU and China (USDA 

FAS, 2012b). 

Approximately 15 to 20

percent of U.S. corn 

production is exported.

The U.S. was responsible 

for 38 percent of the 

world’s bulk soybean 

exports, 13 percent of the 

world’s soybean meal 

exports, and 11 percent of 

the world’s soybean oil 

exports in 2011/12. (USDAERS, 2012b).

The U.S. will continue to 

be an exporter of corn 

and soybeans. Dow has 

submitted or is planning 

to submit requests for 

regulatory approvals in 

the main export markets 

for corn and soybean for 

DAS-68416-4 soybean, 

DAS-44406-6 soybean, 

and DAS-40278-9 corn. 

Therefore, the presence 

of these traits in exported 

commodities will not 

affect trade differently 

than other approved GE 

traits in commerce.

The U.S. will continue to 

be an exporter of corn 

and soybeans. Dow has 

submitted or is planning 

to submit requests for 

regulatory approvals in 

the main export markets 

for corn for DAS-40278-

9 corn. Therefore, the 

presence of this trait in 

exported commodities 

will not affect trade

differently than other 

approved GE traits in 

commerce.

The U.S. will continue to 

be an exporter of corn 

and soybeans. Dow has 

submitted or is planning 

to submit requests for 

regulatory approvals in 

the main export markets 

for soybean for DAS68416-4 soybean and 

DAS 44406-6 soybean. 

Therefore, the presence 

of these traits in exported 

commodities will not 

affect trade differently 

than other approved GE 

traits in commerce.

Food and Feed Both corn and soybean

produced in the U.S. are 

used for food and feed. It 

is the responsibility of 

No change is expected 

relative to the No 

Action Alternative. 

No change is expected 

relative to the No 

Action Alternative.

No change is expected 

relative to the No 

Action Alternative.

18
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

food and feed 

manufacturers to ensure 

that the products they 

market are safe and labeled 

properly.

Dow has completed 

consultations with FDA 

for DAS-40278-9 corn 

(US-FDA, 2011a) DAS68416-4 soybean (USFDA, 2011b) and DAS44406-6 soybean (USFDA, 2013a). 

Worker Safety Workers are exposed to 

corn and soybean plants. 

Workers use farm 

equipment for field 

cultivation and pesticide 

application. 

EPA sets the conditions for 

pesticide use on the label to 

achieve a standard of a 

“reasonable certainty of no 

harm.” The current labels 

for 2,4-D, quizalofop, 

glufosinate, and glyphosate 

include label use restrictions 

intended to protect humans, 

including protective 

EPA is currently 

considering the use of 

Enlist DuoTM and 

quizalofop on DAS40278-9 corn and Enlist 

DuoTM on DAS-68416-4 

soybean and DAS-44406-

6 soybean. EPA sets the 

conditions for pesticide 

use on the label to achieve 

a standard of a 

“reasonable certainty of 

no harm.” 

Impacts are similar to 

those under the Preferred 

Alternative. 

Impacts are similar to 

those under the Preferred 

Alternative.

19
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

equipment to be worn 

during mixing, loading, 

applications and handling, 

equipment specifications to

control pesticide 

application, and reentry 

periods establishing a safe 

duration between pesticide 

application and exposure to 

the pesticide in the field.

Used in accordance with the 

label, these herbicides have 

been determined to not 

present a health risk to 

humans.

Biological Resources

Animal 

Communities

No impacts are expected 

from pesticide use because 

EPA sets the conditions 

for pesticide use on the 

label to achieve a standard 

of a “reasonable certainty 

of no harm.” 

Unchanged from the No 

Action Alternative. No 

impacts are expected 

from the AAD-1 protein 

as it is does not appear to 

be allergenic or toxic.

Unchanged from the No 

Action Alternative. No 

impacts are expected 

from the AAD-1 protein 

as it is does not appear to 

be allergenic or toxic.

Unchanged from the No 

Action Alternative. No 

impacts are expected 

from the AAD-12 protein 

as it is does not appear to 

be allergenic or toxic.

Plant 

Communities

HR weeds will continue to 

be selected against 

herbicides that are used.

There may be an increase 

in the selection of weeds 

resistant to 2,4-D and 

with multiple resistance 

to 2,4-D and glyphosate.

There may be an 

increase in the selection 

of weeds resistant to 2,4-

D and with multiple 

resistance to 2,4-D and 

glyphosate.

There may be an increase 

in the selection of weeds 

resistant to 2,4-D and 

with multiple resistance 

to 2,4-D and glyphosate.

20
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

Biological 

Diversity

Herbicide use in 

agricultural fields may 

impact biodiversity by 

decreasing weed quantities 

or causing a shift in weed 

species present in the field, 

which would affect those 

insects, birds, and 

mammals that use these 

weeds for habitat or food. 

Tillage decreases 

biodiversity. Under the No 

Action Alternative GR

weeds may be difficult to 

control using herbicides 

and tillage may increase in 

soybean. It is uncertain 

how these two opposing 

effects would impact the 

biodiversity of the farming 

community. 

It is uncertain how the 

Preferred Alternative 

would impact 

biodiversity. EnlistTM

cropping systems for 

soybean may help to 

preserve gains in 

conservation tillage and 

increase biodiversity. If 

tillage is used anyway 

and herbicide control of 

weeds is more effective 

than under the No Action 

Alternative, biodiversity 

could decrease relative to 

the No Action 

Alternative. 

Unchanged from the No 

Action Alternative.

Unchanged from the 

Preferred Alternative.

21
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

Natural Resources

Soil Quality Increased tillage to 

manage GR weeds may 

occur in soybean and lead 

to decreased soil quality

from increased soil 

erosion.

EnlistTM cropping systems 

for soybean may help to 

preserve gains in 

conservation tillage and 

benefit soil quality in the 

short term. In the long 

term, selection of 2,4-D 

resistant weeds may 

result in similar 

aggressive tillage 

practices that are 

expected to occur under 

the No Action 

Alternative and negate 

the benefits mentioned 

above.

Unchanged from the No 

Action Alternative.

Unchanged from the 

Preferred Alternative.

Soil 

Microorganisms

Increased tillage to 

manage GR weeds may 

occur in soybean and lead 

to decreased plant residue 

and decrease soil organic 

matter which otherwise

benefits soil biota by 

providing additional food 

sources (USDA-NRCS, 

1996) and increases the 

diversity of soil 

microorganisms.

EnlistTM cropping systems 

for soybean may help to 

preserve gains in 

conservation tillage and 

benefit soil 

microorganisms in the 

short term. In the long 

term, selection of 2,4-D 

resistant weeds may 

result in similar 

aggressive tillage 

practices that are 

Unchanged from the No 

Action Alternative.

Unchanged from the 

Preferred Alternative.

22
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

expected to occur under 

the No Action and negate 

the benefits mentioned 

above.

Water Resources Increased tillage to manage 

GR weeds may occur in 

soybean and lead to 

increased soil erosion and 

decreases in water quality 

from sedimentation. 

EnlistTM cropping systems 

for soybean may help to 

preserve gains in 

conservation tillage in 

the short term. In the 

long term, selection of 

2,4-D resistant weeds 

may result in similar 

aggressive tillage 

practices that are 

expected to occur under 

the No Action 

Alternative and negate 

the benefits mentioned 

above.

Unchanged from the No 

Action Alternative.

Unchanged from the 

Preferred Alternative.

Air Quality Increased tillage to 

manage GR weeds in 

soybean may occur and 

lead to decreased air 

quality from increased air 

particulates and exhaust 

from farm equipment.

EnlistTM cropping systems 

for soybean may help to 

preserve gains in 

conservation tillage and 

benefit air quality in the 

short term. In the long 

term, selection of 2,4-D 

resistant weeds may 

result in similar 

aggressive tillage 

Unchanged from the No 

Action Alternative. 

Unchanged from the No 

Action Alternative.

23
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

practices that are 

expected to occur under 

the No Action 

Alternative and negate 

the benefits mentioned 

above.

Climate Change There is a potential impact 

on climate change from 

increased herbicide use

and more aggressive 

tillage regimes to control 

herbicide-resistant weeds, 

causing increased release 

of GHG from burning 

additional fossil fuels.

EnlistTM cropping systems 

for soybean may help to 

preserve gains in 

conservation tillage and 

reduce GHG

contributions to climate 

change in the short term. 

In the long term, 

selection of 2,4-D 

resistant weeds may 

result in similar 

aggressive tillage 

practices that are 

expected to occur under 

the No Action and negate 

the benefits mentioned 

above.

Unchanged from the No 

Action Alternative.

Unchanged from the No 

Action Alternative.

Other U.S. 

Regulatory 

Approvals

FDA consultations for 

DAS-40278-9 corn (USFDA, 2011b), DAS68416-4 soybean (USFDA, 2011c), and DAS4406-6 soybean (USUnchanged from the 

No Action 

Alternative

Unchanged from the 

No Action 

Alternative.

Unchanged from the 

No Action 

Alternative.

24
Attribute/Measure Alternative 1: No Action

(Deny All Petitions)

Alternative 2: Preferred 

AlternativeDetermination of 

Nonregulated Status for 

DAS-68416-4 Soybean, 

DAS-44406-6 Soybean, 

and DAS-40278-9 Corn

Alternative 3: 

Determination of 

Nonregulated Status of 

DAS-40278-9 Corn Only

Alternative 4:

Determination of 

Nonregulated Status of 

DAS-68416-4 Soybean 

and DAS 44406-6 

Soybean Only

FDA, 2013a) are 

completed. The 

reregistration decision 

for 2,4-D was issued in 

2005 (US-EPA, 2005b). 

EPA is currently 

considering the use of 

EnlistTM on these DAS

corn and soybean events

Approvals in 

other Countries

Approvals have been 

granted for food and 

feed in Canada, 

Columbia, Australia, 

New Zealand, Japan, 

Korea, Mexico, and 

South Africa for one or 

more of the EnlistTM

corn and soybean events. 

Applications are pending 

in Argentina, Brazil, 

China, EU, , and 

Switzerland.

Unchanged from the 

No Action 

Alternative.

Unchanged from the 

No Action 

Alternative.

Unchanged from the 

No Action 

Alternative.

Compliance with Other Laws

CWA, CAA, 

E.O.s and EAS

Compliant. Compliant. Compliant. Compliant.

25
3 AFFECTED ENVIRONMENT

This section includes a review of the prevailing conditions (baseline) of the human environment 

in the major corn and soybean production regions of the conterminous U.S. that may be further

impacted by a determination of nonregulated status of DAS-40278-9 corn, DAS-68416-4 

soybean, and DAS-44406-6 soybean. Relevant components of the physical environment, 

biological resources, human health, animal feed, and socioeconomic resources are considered. 

They include soil, water and air quality, climate change, land cover and land uses, corn and 

soybean production practices, animal communities, food and feed uses, worker safety and 

agricultural markets.

3.1 U.S. Corn and Soybean Production Practices

U.S. corn and soybean acreage combined is concentrated in the eastern two-thirds of the 

conterminous 48 states. The map shown in Figure 1 illustrates the major regions where one or 

both of these crops are grown. Very little production occurs in Hawaii, Alaska, and U.S.

Territories and is therefore not included on the map. The individual highlighted areas correspond 

to ecological zones that are described in detail in section 3.1.3.

Figure 1. Major Corn and Soybean Cultivation Regions in the U.S.

26
3.1.1 Corn

Worldwide, corn production is exceeded only by wheat. This is attributable to corn’s ability to 

adapt to a wide range of production environments, including variable conditions of humidity, 

sunlight, altitude, and temperature (OECD, 2003).

Corn is an annual typically grown in zones of abundant rainfall and fertile soils (OECD, 2003). 

In the U.S., prevailing moisture levels and the number of frost-free days represent climatic 

conditions ideal for corn production (IPM, 2004; 2007). According to the 2007 Census of 

Agriculture, corn was harvested for grain and/or silage in all 48 conterminous U.S. states in 89

percent (2,754) of the 3,109 counties and county equivalents within this region (Figure 2) 

(USDA-NASS, 2009e).

Figure 2. Corn Cultivation in the 48 Conterminous U.S.

Source:(USDA-NASS, 2009e).

Approximately 98 percent of the U.S corn crop is grown in the eastern two-thirds of the U.S. The 

greatest concentration of production occurs in the Corn Belt, which is loosely defined as Illinois, 

Iowa, Indiana, southern and western Minnesota, eastern South Dakota and Nebraska, western 

Kentucky and Ohio, and the northern two-thirds of Missouri (USDA-ERS, 2011c; USDA-NASS, 

2010b; 2011b). The leading corn-producing states of Illinois, Iowa and Nebraska account for 

approximately 40 percent of the annual U.S. harvest (USDA-ERS, 2011b).

3.1.2 Soybean

Soybean (Glycine max (L.) Merr.) is an economically important leguminous crop, providing oil 

and protein from processed seed. Soybean is the most economically important oil-seed27
producing crop in the world. It accounts for 58 percent of global oil-seed production (ASA, 

2011).

According to the 2007 Census of Agriculture, soybean was harvested in 2,039 (66 percent) 

counties or county equivalents in the conterminous U.S. (USDA-NASS, 2009d) (Figure 3). 

About half of the 2012 U.S. crop was concentrated in five states: Iowa, Illinois, Minnesota, 

Indiana, and Nebraska(USDA-NASS, 2013a).

Figure 3. Soybean Cultivation in the Conterminous U.S.

Source: (USDA-NASS, 2009e).

3.1.3 Ecoregions of Major U.S. Corn and Soybean Production Areas

The affected environment includes a number of ecological regions (ecoregions) defined by the 

EPA and the Canada-Mexico-US Commission for Environmental Cooperation (CEC). 

Ecoregions are areas that are similar in type, quality, and quantity of environmental resources 

(CEC, 2009). The CEC uses a hierarchical system to classify ecoregions into three different 

levels. The broadest one is Level I. It divides North America into 15 ecological regions. These 

are subdivided into 50 Level II ecoregions that are then further subdivided into 182 Level III 

subregions. Each Level III subregion is defined by a variety of physical, biological, and human 

factors. These include location, climate, terrain, hydrology, vegetation, wildlife, and land use

associated with human activities. The EPA ecoregions correspond to the CEC Level III 

subregions. A map showing the Level III subregions of the conterminous U.S. appears in Figure 

4.

28
Figure 4. Ecoregions of the Conterminous U.S. 

Source: (CEC, 2006)

Descriptions of the physical and biological environments in the discussion that follows are based 

primarily on CEC and EPA Level III definitions. In some instances, they are supplemented by 

EPA Level IV definitions unless otherwise cited (CEC, 2011; US-EPA, 2010b).

There are 13 regions within the affected environment in the conterminous U.S. where 

commercial corn and soybean production occur (Figure 1 and Figure 4, Table 2). Most are in 

Level I ecoregion 8 (Eastern Temperate Forests: Regions A-G in this EIS) or 9 (Great Plains: 

Regions H-K in this EIS). Ecoregion 8 covers most of the eastern half of the conterminous U.S.

and is distinguished by its moderate to mildly humid climate, dense and diverse forest cover, and 

high density of human inhabitants, industry, and agriculture. Ecoregion 9 is in the central U.S. It 

is characterized by a sub-humid to semiarid climate that supports grasslands with minimal 

topographic relief. The density of agriculture is higher than that of Ecoregion 8 and the density 

of human inhabitants is lower. Ecoregion 9 is among the largest farming and ranching areas in 

the world.

A small portion of the environment affected only by corn production is in two Level I 

ecoregions: 10 (North American Deserts) and 11 (Mediterranean California). Only about 1

percent of U.S. corn cultivation occurs in these two ecoregions combined, but corn cultivation is 

a significant component of the agriculture production within them, so corn cultivation is locally 

important to both.

29
Table 2. Location and Relative Distribution of Corn/Soybean Cultivation

Region CEC/EPA 

Ecoregion

Location of Corn and 

Soybean Cultivation

Area

(sq. 

miles)

Percent of U.S. 

Harvest*

Corn Soybean

A—Mixed Wood 

Plains (central portion)

 —Appalachian 

Forests (northern 

portion)

8.1.1/83

8.1.3/60 (corn 

only)

8.1.10/61

8.4.2/69 

(northern, corn 

only)

8.4.3/70 

(northern, corn 

only)

Upstate NY

Northeastern OH

Northeastern and western 

PA

Western VT

60,032 2.6% 1.3%

B—Mixed Wood 

Plains (western 

portion)

8.1.4/51

8.1.5/52

8.1.6/56

5.2.1/50 (along 

8.1.4 border, corn 

only)

Northwestern IL

Northern IN

Northeastern IA

Central and southern MI

Central and western WI

98,213 9.0% 5.7%

C—Central USA 

Plains

8.2.1/53

8.2.2/57

8.2.3/54

8.2.4/55

Northern and central IL

Eastern, central and 

northwestern IN

MI - east of Lake Erie and 

southeast of Lake Huron

Western OH

Southeastern WI

83,387 17.8% 17.3%

D—Southeastern USA 

Plains (eastern 

portion)

 —Appalachian 

Forests (northeastern 

portion)

 —Coastal Plains 

(southeastern portion)

8.3.1/64

8.3.4/45

(northern)

8.3.5/65 (eastern)

8.4.1/67 

(northern)

8.5.1/63

DE

Central and southwestern 

GA

MD (most)

Northwestern and 

southwestern NJ

Eastern and central NC

Eastern and central PA

Eastern SC

Eastern and northwestern 

VA

131,651 4.3% 5.5%

E—Southeastern USA 

Plains (northwestern 

portion)

8.3.2/71 8.3.3/72

8.4.5/40 

(northern, along 

8.3.2 border)

North-central AL

Western and southern IL

Southwestern IN

Southeastern edge IA

Central and western KY

Eastern edge and central 

97,017 8.4% 9.4%

30
Region CEC/EPA 

Ecoregion

Location of Corn and 

Soybean Cultivation

Area

(sq. 

miles)

Percent of U.S. 

Harvest*

Corn Soybean

MO North-central and 

south-central TN

F—Mississippi Alluvial 

Plains

 —Southeastern USA 

Plains (western 

portion)

8.3.5/65 

(western)

8.3.6/74

8.3.7/35 (Red 

River only)

8.5.2/73

9.5.1/34 (eastern)

Eastern and southwestern 

AR

Western KY

Northeastern, central and 

south-central LA 

Western and northern MS

Southeastern MO

Western TN

79,506 3.5% 11.7%

G—Temperate 

Prairies

9.2.1/46

9.2.2/48

9.2.3/47

9.2.4/40

IA (most)

Eastern KS

Western and southern MN

Northern and western MO

Eastern NE

Eastern and north-central 

ND

Eastern SD

201,400 33.4% 37.9%

H—West-Central 

Semi-Arid Prairies 

(eastern portion)

9.3.1/42

9.3.3/43 (eastern, 

corn only)

North-central NE (small 

area)

Central and south-central 

ND

Central SD

65,376 2.9% 2.2%

I—South-Central 

Semi-Arid Prairies 

(northern and central 

portions)

9.4.1/25

(corn only)

9.4.2/27 

(northern)

9.4.4/28

Eastern CO

Kansas (most)

Western and south-central 

NE

Eastern NM

Texas Panhandle

Southeastern WY

183,588 12.3% 6.1%

J—Texas Blackland 

Prairies

9.4.7/32 Central TX 14,130 0.5% 0%

K—Western Gulf 

Coastal Plain

9.5.1/34 Central Gulf Coast of TX 

(corn only)

28,863 0.4% 0%

L—Snake River Plain 10.1.8/12 Southern ID

Southeastern OR

20,667 0.4% 0%

M—Central California 

Valley

11.1.2/7 Sacramento and San 

Joaquin Valleys CA

17,801 0.6% 0%

*

Source: USDA-NASS CropScape 2012 land cover data (USDA-NASS, 2013i); full 2007 dataset 

not available.

31
3.2 Physical Environment

The physical environment includes a description of the location and physical terrain within each 

region, its soil and water resources, air quality, climate and climate change considerations. The 

primary locations of corn and soybean cultivation within Regions A-M are described in Table 2.

3.2.1 Physical Terrain and Climate

Region A is characterized by rolling hills, level ground or open valleys with low mountains 

along the NY-PA border; low rounded hills, scattered end moraines, kettles, and areas of 

wetlands to the west (8.1.10); a variety of deep glacial and marine deposits to the east (8.1.1). It 

has a severe mid-latitude humid continental climate marked by warm summers and cold winters, 

with a mean annual temperature of 5-10 degrees Celsius (°C). The frost-free period is 120-200 

days. Annual precipitation is 720-1,270 millimeters (mm). Locations in closer proximity to the 

Great Lakes experience a longer growing season, more winter cloudiness, and greater snowfall.

Region B is characterized by a diverse range of landforms. These include nearly level to rolling 

plains formed from glacial deposits and outwash (some with thick complex deposits of drift), 

rolling to hilly moraines, deeply dissected and loess-capped plateau, lacustrine basins, and 

meltwater channels. It has a severe, mid-latitude, humid continental climate with warm/hot 

summers and severe winters. There is no distinguishable dry season. The mean annual 

temperature is 5-10°C with a frost-free period of 130-200 days. Annual precipitation is 600-990

mm. Winters are snowy in the north and west.

Region C is predominantly flat to rolling glacial plains, with some lacustrine clay plains, pitted 

outwash plains, sand dunes, and moraines. It has a severe, mid-latitude, humid continental 

climate marked by warm/hot summers and cold winters. The mean annual temperature is 7-13°C. 

The frost-free period is 150-200 days, and annual precipitation is 700-1,150 mm.

Region D includes low-rounded or irregular hills, ridges, irregular plains and rolling or open 

valleys to the north and west (8.3.1, 8.3.4, northern 8.4.1). Flat, rolling to smooth coastal plains 

prevail in the south and east (8.3.5 and 8.5.1). It has a mild, mid-latitude, humid, subtropical 

climate with hot humid summers and mild winters, except for the northern areas (8.3.1 and 

northern 8.4.1). The latter have severe, mid-latitude climates or are transitional areas with cold 

winters. The mean annual temperature range is 8-17°C, and the frost-free period is 145-300 days. 

Annual precipitation is 900-1,520 mm.

Region E consists of wide, flat-bottomed, terraced valleys, valley slopes, and river bluffs to the 

north and west (8.3.2). Dissected glacial till plains occur in IL and IN. A broader variety of 

landforms are found in the east and south (8.3.3), including gently sloping, rolling and irregular 

plains, dissected plateaus, tablelands and open hills. A severe, mid-latitude, humid, continental 

climate with hot summers and cold winters occurs in the north and west. A mild, mid-latitude, 

humid, subtropical climate (hot summers and mild winters) with no distinguishable dry season 

prevails in the south and east. The mean annual temperature range is 10-16°C. The frost-free 

period is 160-220 days. Annual precipitation is 850-1,470 mm. Precipitation tends to be higher in 

the south and east.

32
Region F has mostly broad and flat alluvial plains with river floodplains, terraces, swales, 

levees, oxbow lakes, and backswamps to the west (8.5.2 and 8.3.7). Irregular plains with some 

gently rolling hills occur in the east (8.3.6 and northwestern 8.3.5). Thick deposits of sandy to 

clayey alluvium occur in the west, thick deposits of loess are found in the central region, and 

fine-textured clayey sand and some loess prevail in the east and north. The region has a mild, 

mid-latitude, humid subtropical climate with hot and humid summers, and mild winters. The 

mean annual temperature range is 13-21°C. The frost-free range is generally 200-300 days, but 

approaches 350 days near the Gulf of Mexico. Annual precipitation is 1,140-1,650 mm. Rainfall 

amounts tend to be evenly distributed throughout the year, but tend to be greater in the south.

Region G has flat to gently rolling glacial till plains with thick beds of lake sediments on top and 

hilly loess plains with thick layers of loess. The southernmost part of the region is 

topographically hillier than the rest. The region has a severe, mid-latitude, humid continental 

climate, with a milder humid subtropical climate in the southernmost area (9.2.4). Summers are 

short but warm. Long cold winters with nearly continuous snow cover occur to the north. Longer 

hotter summers and cold, but somewhat milder winters are typical in the south. The mean annual 

temperature range is 3-16°C. The frost-free period is 90-225 days. Annual precipitation is 400-

1,145 mm, increasing from northwest to southeast. Most precipitation occurs during the growing 

season.

Region H is characterized by rolling hills and gentle plains mantled almost entirely by moraine, 

outwash, and glaciolacustrine sediments. It has a dry, mid-latitude steppe climate with warm to 

hot summers and cold winters. The mean annual temperature range is between 3°C in the north 

to 9°C in the south. The frost-free range is 95-150 days. Annual precipitation ranges from 250 

mm to 510 mm.

Region I is composed primarily of smooth, level to slightly irregular plains, with broad alluvial 

valleys and some hillier dissected plains in the central part of the region (9.4.2). Rolling hills and 

narrow steep valleys occur in the east (9.4.4). Climate varies across both directional gradients 

(i.e., north-south and east-west). The west has a mid-latitude steppe climate. The east has a midlatitude humid continental climate. Summers are hot and winters are cold in the north and milder 

along the gradient southward south. Mean annual temperatures range from 8°C (north) to 18°C 

(south). The frost-free date range is 120 – 230. Annual precipitation ranges from 300 to 1,065 

mm. It tends to be significantly greater in the easternmost part of the region (9.4.4) than 

elsewhere.

Region J is characterized by nearly level to gently sloping plains that are lightly to moderately 

dissected. It has a mild mid-latitude humid subtropical climate (i.e., hot summers; mild winters). 

The mean annual temperature range is 17-21°C and the frost-free period is 240-290 days. Annual 

precipitation is 760-1,170 mm. It declines along the north to south gradient.

Region K tends to be gently sloping coastal plains in the agricultural areas, with sediments of 

marine sand, silt, and clay. It has a mild, mid-latitude, humid subtropical (hot summers; mild 

winters). The mean annual temperature is in the range of 20-25°C. There is a long frost-free 

period (270 – 365 days). The mean annual precipitation range is 600-1,625 mm. There is a steep 

increase in precipitation along the southwest to northeast gradient.

33
Region L is characterized by alluvial valleys, plains, and low hills, interspersed with scattered 

barren lava fields. It has a dry, mid-latitude steppe climate marked by warm summers and cold 

winters. The mean annual temperature range is 6-10°C, increasing along the east-to-west

gradient. The frost-free period ranges from 90 – 170 days, decreasing from west to east, which 

corresponds to increasing elevation. The mean annual precipitation range is 150-400 mm.

Region M is characterized by flat fluvial plains filled with deep and well-drained loamy or 

clayey soils formed by deposits washed down from the surrounding mountains. It has a 

Mediterranean climate, with long, hot dry summers and mild, slightly wet winters. The mean 

annual temperature range is 15-19°C, with a frost-free period of 240 to 350 days. The mean 

annual precipitation ranges from 125 mm in the south to 760 mm in the north.

3.2.2 Soil Resources

Soils are an admixture of weathered minerals, organic matter, air and water. They are formed 

mainly by the weathering of rocks, the decaying of plant matter, and the deposition of materials 

such as chemical and biological fertilizers that are derived from other origins.

Particle size, texture and color are important attributes used to classify a soil type into one of 

twelve taxonomic orders. Properties such as organic matter content and degree of soil profile 

development are also used (Brady & Weil, 1996) to systematically classify soils according to 

relationships that define their character (USDA-NRCS, 1999b). Eight soil orders (Table 3) are 

predominant in areas where corn and soybean are grown.

Corn is cultivated in a wide variety of soils across the U.S. (see, e.g., Corn Crop Profiles 

provided at www.ipmcenters.org). Soybean production is best suited to fertile, well-drained, 

medium-textured loam soils, yet they can also be produced in a wide range of soil types 

(Berglund & Helms, 2003; NSRL, No Date).

Table 3. Affected Environment: Dominant and Major Secondary Soil Types by Region

Soil Order Description Region

Alfisols A dark surface horizon mineral soil, similar to 

mollisols however, lacking the same level of fertility 

and more acidic.

A, B, C, D, E, F, 

G, I, J, K, M

Aridisols These soils are found in the arid regions of the US. 

Typically high in calcium, magnesium, potassium and 

sodium. The soils have an alkaline pH.

L, M

Entisols This soil order is relatively un-weathered. These soils 

have no diagnostic horizon development. Often found 

on floodplains, glacial outwash areas and other areas 

receiving alluvial materials.

B, F, H, M

34
Soil Order Description Region

Histosols Dominated by organic soil materials, some consist of 

a thin layer of organic materials over a root-limiting 

layer or fragmental materials; commonly called bogs, 

peats, mucks

B

Inceptisols Soils of the humid and sub humid region. Weathering 

has created minimal diagnostic differentiation in the 

soil column.

A, B, C, D, E, F

Mollisols Dark colored mineral soils developed under grassland 

conditions. Rich in nutrients, very fertile. Associated 

with the corn belt.

A, B, C, E, G, H, 

I, J, L, M

Ultisols Highly weathered soils found in hot, moist regions. 

Typically acidic and low in available nutrients.

D, E

Vertisols Soils having significant amounts of expanding clay 

content. Soils typically crack when dry and swell 

when wet.

F, G, H, J, K, M

Source: (USDA-NRCS, 1999b)

Soil properties are dynamic. Temperature, pH, soluble salts, amount of organic matter, the 

carbon-nitrogen ratio, numbers of microorganisms, and soil fauna all vary seasonally, and shifts 

in these parameters also occurs over broader extended periods(USDA-NRCS, 1999b). Soil 

texture and organic matter levels directly influence shear strength, nutrient holding capacity, and 

permeability(McCauley et al., 2005). Soil types also influence susceptibility to erosion by wind 

and water and the capacity to attenuate flooding (McCauley et al., 2005).

Soil erosion is a naturally occurring event and the erosion rates are relatively slow; however, 

human activity can greatly accelerate the rate of erosion. In general, wind and/or water erosion 

are important soil resource concerns in the major U.S. corn- and soybean-growing. Wetness and 

maintenance of organic matter content in the Corn Belt (USDA-FSA, 2010) are of similar 

importance. Figure 5 depicts a USDA map of erosion exceeding the soil loss tolerance rate on 

cropland in the U.S. (USDA-NRCS, 2011). Excessively eroding cropland soils are concentrated 

in Midwest and Northern Plain States and in the Southern High Plains of Texas (regions C, G, 

and I). Land management practices for crop cultivation can also affect soil quality. Tillage, use 

of pesticides and fertilizers and other practices can improve soils, but must be applied using good 

management practices) to avoid degrading soil quality. Several concerns relating to soil and 

agricultural practices include increased erosion, soil compaction, degradation of soil structure, 

nutrient loss, increased salinity, change in pH, and reduced biological activity (USDA-NRCS, 

2001b). Conventional tillage entails removal of all plant residues and weeds from the soil surface 

prior to planting. It also requires continued cultivation as the crop develops to control late 

35
emerging weeds (NCGA, 2007b). This practice increases the potential for soil loss from wind 

and water erosion (NCGA, 2007b).

Soil conservation practices, include conservation tillage, reduce field tillage and corresponding 

soil loss (USDA-NRCS, 2006c). Conservation tillage relies on methods that result in less soil 

disruption and leaves at least 30 percent of crop residue on the surface(Peet, 2001). No-till 

farming only disturbs the soil during seeding operations. The new crop is planted into residue or 

in narrow strips of tilled soil (Peet, 2001), which results in less soil disruption.

Reducing tillage has several benefits for soil health, but there are associated management 

concerns. Under no-till practices, soil compaction may become a problem because tillage is 

useful for breaking up compacted areas (USDA-NRCS, 1996). Reducing tillage may also 

enhance conditions for development of economically significant pest populations that are

managed more efficiently with conventional tillage (NRC, 2010). Another consideration is soil 

type because not all soils (such as wet and heavy clay soils in northern latitudes) are suitable for 

no-till practices.

Inorganic and organic matter in soil supports a diversity of fungi, bacteria, and arthropods that 

are important components of the growth medium for terrestrial plant life (USDA-NRCS, 2004). 

Soil microorganisms are critical for soil structure formation, decomposition of organic matter, 

toxin removal, nutrient cycling, and most biochemical soil processes (Garbeva et al., 2004; 

Jasinski et al., 2003; Young & Ritz, 2000). They also suppress soil-borne plant diseases and 

promote plant growth (Doran et al., 1996).

36
Figure 5. Locations of Excessively Eroding U.S. Croplands

Source: (USDA-NRCS, 2011)

The main factors affecting microbial population size and diversity include: (1) the plant species, 

cultivars, and developmental stages present, which provide specific carbon and energy inputs 

into the soil; (2) soil type (determined by texture, structure, organic matter, aggregate stability, 

pH, and nutrient content); (3) geographic location; (4) season; (5) weather; (6) agricultural 

management practices (crop rotation, tillage, herbicide and fertilizer application, and irrigation) 

(Garbeva et al., 2004; Kowalchuk et al., 2003; Young & Ritz, 2000).

Plant roots, including those of soybean, release a variety of compounds into the soil that created 

a unique environment for microorganisms in the rhizosphere. These include mycorrhizal fungi, 

nitrogen-fixing bacteria, and some free-living microbes that have co-evolved with plants that 

supply nutrients to obtain food from their plant hosts (USDA-NRCS, 2004). Microbial diversity 

in the rhizosphere may be extensive and differs from the microbial community in the bulk soil 

(Garbeva et al., 2004). Tillage disrupts multicellular relationships among microorganisms, and 

crop rotation changes soil conditions in ways that favor different microbial communities.

37
3.2.3 Water Resources

Resources analyzed in this section include the quality and quantity of water in surface and 

groundwater. Impacts from human consumption, particularly water for irrigating agricultural 

production, are also reviewed.

Surface water in rivers, streams, creeks, lakes, reservoirs, wetlands and estuaries provides water 

for drinking, irrigation, industrial, recreational and other public uses. About 66 percent of water 

used in the U.S. in 2005 (about 410 billion gallons per day) was from fresh surface water sources 

(USDA-FSA, 2010).

Groundwater from aquifers sustains ecosystems by releasing a continuous supply of water into 

wetlands, and permanent streams and rivers. In 2005, it contributed about 19 percent of 

freshwater used in the U.S. (USDA-FSA, 2010). Groundwater supplies drinking water for 

approximately 47 percent of the U.S. population (McCray, 2009).

Water in agriculture is used for irrigation, pesticide and fertilizer applications, crop cooling (e.g., 

light irrigation), and frost control (US-CDC, 2009). Moisture availability and use for crop 

irrigation are important determinants of yield. Irrigation maintains adequate moisture for a crop, 

so it contributes to agriculture production by increasing yields per acre, and by making more 

acreage (i.e., dry lands) usable. It also moderates fluctuations in product quality. Moisture 

requirements for most crops tend to vary during development. An adequate water supply permits 

irrigation during critical periods of the growing cycle, so is an important contributor to both 

optimal quality and yield (US-EPA, 2012b).

Irrigation is especially important to agriculture in the western U.S. and the Mississippi River 

Valley (Figure 6). Most irrigation in California (region M) is used for alfalfa, cotton, orchards, 

and vegetables rather than corn. In Idaho (region L), most irrigation is for wheat, alfalfa and row 

crops (USDA-NASS, 2009a). Nationally, less than 10 percent of soybean acres and 

approximately 15 percent of corn acres are irrigated. However, corn accounts for about 25

percent of irrigated acres nationally, while soybean accounts for about 25 percent of irrigated 

acres in the eastern 31 states (Schaible & Aillery, 2012). Corn is heavily irrigated in the western 

plains states (region I; particularly Nebraska, Kansas, and the Texas panhandle). Soybean is 

heavily irrigated in central Nebraska (region I) and both corn and soybean are heavily irrigated in 

the Mississippi River Valley (region F) (USDA-NASS, 2009b; c).

Both groundwater and surface water can be used for irrigation, which accounted for 

approximately 28 percent of withdrawals from fresh surface water sources and about 67 percent

of withdrawals from fresh groundwater sources in 2005 (USDA-FSA, 2010). Groundwater 

sources are especially important for irrigation in the regions mentioned above, with seven states 

(California, Nebraska, Arkansas, Texas, Idaho, Kansas, and Colorado) accounting for over 70 

percent of total groundwater withdrawals in 2005. In four of these states (Arkansas, Kansas, 

Nebraska, and Texas), fresh groundwater accounted for 75 to 96 percent of all irrigation water. 

Groundwater use also exceeded 90 percent of that for irrigation in Mississippi and Missouri 

(USDA-FSA, 2010). Groundwater serves as the source of about 90 percent of irrigated corn 

acreage in the U.S. (Christensen, 2002; US-EPA, 2012b).

38
Figure 6. U.S. Irrigated Acreage, 2007

Source: USDA, National Agricultural Statistics Service, Map # 07-M080 (USDA-NASS, 2009a).

In addition to the Level III and Level IV Ecoregion descriptions, information on water resources

was obtained from the U.S. Geological Survey (Konikow, 2013; USGS, 2013b).

Region A contains perennial streams, the Hudson River and several other large rivers, Lake 

Ontario, the Finger Lakes, and a number of small lakes, and abundant wetlands in some areas. 

Region B has many perennial streams, with wetlands and lakes more common in northern areas. 

The northern Mississippi River runs through the region. Groundwater is abundant and is the 

major source of irrigation water in Minnesota and Wisconsin (USDA-FSA, 2010).

Region C has a low to medium density of perennial streams, which are often intermittent in the 

southern portions of the region. Some areas have lakes, wetlands, and abundant groundwater. 

These are major sources of irrigation water in Illinois and Wisconsin. Drainage has been greatly 

modified in 8.2.2 and 8.2.3, and stream chemistry, turbidity, and habitat have been affected by 

agriculture.

Region D has a moderate to dense network of streams and rivers. Some reservoirs and a few 

natural lakes are present in the north. Numerous swamps and marshes prevail in the south. The 

Roanoke, Savannah, and Susquehanna Rivers run through the region.

39
Region E has numerous perennial streams and rivers in 8.3.2. Silt and sand dominate lowland 

channels; upland streams are rockier. There are both perennial and intermittent streams and 

numerous springs in 8.3.3, with higher nutrient, alkalinity and hardness levels than the streams in 

8.3.2. In the Western Pennyroyal region of Kentucky and Tennessee a complex of numerous 

sinkholes, ponds and well-developed underground drainage system promote rapid surface soil 

moisture loss. Major rivers crossing this region include the Illinois, Missouri, Mississippi, Ohio, 

Tennessee and Wabash.

Region F is dominated by the Mississippi River. One of the largest continuous wetland systems 

in North America was also present in this region, but extensive areas have been modified by 

channelization, and other navigation and flood control engineering projects. The Red River also 

runs through the region, and oxbow lakes, backswamps, and ponds also occur. In the eastern part 

of the region there are few lakes but a moderate to dense network of perennial and intermittent 

streams and rivers, including the Tombigbee. The Mississippi alluvial valley aquifer is the major 

groundwater irrigation (USDA-FSA, 2010). Water withdrawals from the aquifer greatly exceed 

recharge from surface waters (Konikow, 2013).

Region G consists mainly of low density of rivers and intermittent or perennial streams. A 

higher density of rivers occurs in the south, including the Des Moines, Kansas, and Missouri 

Rivers. The Minnesota River and the Red River are the major rivers in the north. Many streams 

and rivers have been channelized. Abundant temporary and seasonal wetlands occur in the north, 

creating favorable conditions for waterfowl nesting and migration. A few large reservoirs occur 

in the south. Groundwater is highly mineralized in some areas. Surface and groundwater

contamination from fertilizer and pesticide applications, and concentrated livestock production 

are significant environmental problems in the central part of the region (9.2.3).

Region H includes primarily intermittent streams and some perennial ones. The Missouri River 

which runs along the western boundary of most of the region is the most important river system. 

In some areas, a high concentration of semi-permanent and seasonal wetlands occurs.

Region I is characterized by intermittent and ephemeral streams in the western part, and 

intermittent and perennial steams in the east. There are few lakes, some springs and ephemeral 

pools and several rivers: Arkansas, Platte, Kansas and their tributaries. The Ogallala aquifer 

underlies large portions of this ecoregion and it is the major source of irrigation water within it 

(USDA-FSA, 2010). Withdrawals from this aquifer greatly exceed recharge from surface waters 

(Konikow, 2013; Steward et al., 2013).

Region J has intermittent and perennial streams. The region lacks lakes but there are many manmade reservoirs.

Region K has intermittent and perennial streams. Some have been channelized. There are 

numerous wetlands in the eastern part of the region.

Region L is traversed by the Snake River. Canals and reservoirs are prevalent in and near 

agricultural areas. Aquifers underlying the Snake River plain are an important groundwater

source for irrigation that is secondary to what is supplied from surface water.

40
Region M has two major river systems, the Sacramento and San Joaquin. Most streams in the 

region are intermittent, being dry during summer months. Some vernal pools, marshes, and 

wetlands also occur. The region has an extensive network of water diversions, man-made 

channels and drainage systems. Management of irrigation water is a priority in the region

(USDA-NRCS, 2006d). Although secondary to surface water, central valley groundwater is a 

major source for irrigation, which is an important consideration since withdrawals currently 

exceed recharge rates (Konikow, 2013).

3.2.4 Water Quality

Natural features (i.e., the physical and chemical properties) of the land surrounding a water body 

have the greatest impact on water quality. The topography, soil type, vegetative cover, minerals, 

and climate also influence water quality. Runoff from rain, snowmelt, or irrigation can affect 

water quality by depositing sediment, minerals, and natural and human-made pollutants into 

lakes, rivers, wetlands, and coastal waters. Major sources of pollutants include storage tanks, 

septic systems, hazardous waste sites, and landfills. Widespread use of road salts, fertilizers, 

pesticides and other agricultural chemicals are also important sources. All surface water 

pollutants have the potential to be transported into groundwater.

Agricultural pollution is the leading source of impacts on surveyed rivers and lakes. It’s also the 

third most significant cause of impairment of water quality in estuaries, and a major source of 

contamination of groundwater and wetlands (USDA-EPA, 2011).

The most common types of agricultural pollutants include excess sediment, fertilizers, animal 

manure, pesticides and herbicides. Management practices that contribute to water contamination 

include the type of crop cultivated, plowing and tillage, and irrigation. Irrigation depletes 

available water and reduces quality by increasing erosion and sedimentation, nutrients dissolved 

in runoff and chemicals adsorbed onto soil particulates washed into surface water. Some of these 

pollutants eventually contaminate groundwater by leaching.

Sediment can directly affect fish, aquatic invertebrates, and other wildlife. It also reduces light 

penetration, which directly impacts aquatic plants. Sediments from erosion contribute to fertilizer 

runoff, water turbidity, algal blooms, and oxygen depletion (US-EPA, 2005a). Fertilizers and 

pesticides have been found to be in excess in many water bodies in the EPA (USDA-FSA, 2010)

has documented over 3 million acres of water bodies and over 75,000 miles of rivers and 

streams, large areas of bays and wetlands with excess levels of nitrogen and phosphorus. These 

two nutrients, when in excess, create harmful blooms of algae and other aquatic flora which 

deplete oxygen that can result in many detrimental effects including fish kills. According to an

EPA Report on the Environment for 2008, groundwater has also been seriously affected by 

various nutrient and pesticides (USDA-FSA, 2010).

3.2.5 Air Quality

The Clean Air Act (CAA) requires National Ambient Air Quality Standards (NAAQSs). These 

are intended to protect public health, and are established by EPA for six criteria pollutants: ozone 

(O3), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2), lead (Pb), and 

41
inhalable particulates. The latter are subdivided into particulate matter (PM, coarse particulate 

matter greater than 10 μm [micrometers]), PM10 (particulates 2.5-10 μm), and PM2.5, (fine 

particles less than 2.5 μm).

The CAA requires states to achieve and maintain the NAAQSs within their jurisdiction. Each 

state must prepare a State Implementation Plan with strategies to achieve and maintain the EPAestablished national standards or more stringent ones within its boundaries. EPA monitors levels 

and designates states as attainment or non-attainment areas for each criteria pollutant.

Some agricultural operations impact air quality. They include smoke from burning, exhaust from 

motorized equipment, and airborne soil particulates from tillage. Aerosols from pesticide 

applications are another source of impacts on air quality. Effects are complex because aerosols 

can: 1) drift from the target site; 2) volatilize, which increases the area impacted; 3) adsorb unto 

soil particles that have the potential to become airborne. Some gases resulting from agricultural 

activities also impact air quality. They include CO2 from equipment exhaust and tillage, CO2 and 

methane from tillage, and oxides of nitrogen associated with fertilizer applications (Aneja et al., 

2009; Hoeft et al., 2000; US-EPA, 2011b; USDA-NRCS, 2006a).

3.2.6 Climate Change

Agriculture is estimated to contribute 6 percent of all human-induced greenhouse gases (GHG)

in the U.S. (US-EPA, 2011b). Emissions of GHG released from agricultural equipment (e.g., 

irrigation pumps and tractors) include carbon monoxide, nitrogen oxides, methane (CH4), 

reactive organic gases, particulate matter, and sulfur oxides (US-EPA, 2011b). Nitrogen-based 

fertilizers applied for crop production are the greatest source of U.S. nitrous oxide (N2O). 

Croplands account for 69 percent of total N2O emissions attributable to agricultural land uses 

(US-EPA, 2011b). Agriculture sources of CH4 emissions are associated primarily with enteric 

emissions of gas from cattle and manure management. CO2 also is a significant GHG associated 

with several agricultural practices, including land uses and energy consumption (US-EPA, 

2011b). 

Tillage contributes to GHG emissions by releasing CO2 from fuel consumption. The more 

aggressive the tillage, the greater the fuel consumption and the greater the GHG emissions. At 

one time it was thought that conservation tillage also promoted carbon sequestration in the soil 

but more recent observations have called that benefit into question (Baker et al., 2007; BlancoCanqui & Lal, 2008). Disruption and exposure of soil also promotes CO2 production from 

oxidation of soil organic matter (Baker et al., 2005). The carbon footprint for corn production has 

been estimated to be approximately 300 pounds of carbon equivalent emission per acre (Nelson 

et al., 2009). The carbon footprint of corn is directly affected by the associated cultivation 

practices. Corn cultivation has been estimated to produce higher total CO2 emissions than 

soybean, and lower total emissions than cotton or rice (Nelson et al., 2009). On-site emissions 

can be reduced by half for some crops by replacing conventional with no-till systems agriculture 

(Nelson et al., 2009). 

Important factors influencing agricultural impacts on climate change include production 

practices specific to the production of various types of commodities, the region in which the 

42
commodities are grown, and individual choices made by growers. For example, emissions of 

N2O, produced naturally in soils through microbial nitrification and denitrification, can be 

influenced dramatically by fertilization, introduction of grazing animals, cultivation of nitrogenfixing crops and forage (e.g., alfalfa), retention of crop residues (i.e., no-till conservation), 

irrigation, and fallowing of land (US-EPA, 2011b). These same agricultural practices can 

influence the decomposition of carbon-containing organic matter sequestered in soil, resulting in 

conversion to CO2 and subsequent loss to the atmosphere (US-EPA, 2011b). Conversion of crop 

land to pasture increases in carbon and nitrogen sequestration in soils (US-EPA, 2011b). 

The EPA has identified regional differences in GHG emissions associated with agricultural 

practices on different soil types, noting that carbon emission rates differ between mineral soils 

and organic soils (US-EPA, 2011b). Mineral soils contain from 1 to 6 percent organic carbon by 

weight in their natural state. Organic soils may contain as much as 20 percent carbon by weight 

(US-EPA, 2011b). Up to 50 percent of the soil organic carbon in mineral soils can be released to 

the atmosphere when land is initially converted to crop production. Over time, the soil 

establishes a new equilibrium that reflects a balance between carbon from decaying plant matter 

and organic amendments, and carbon released by microbial decomposition (US-EPA, 2011b). 

Organic soils continue to release carbon to the atmosphere for a longer period of time than 

mineral-based soils (US-EPA, 2011b) . The EPA has estimated that mineral soil-based cropland 

areas sequestered over 45.7 Tg CO2 Eq5 in 2008. Carbon emissions from croplands with organic 

soils were estimated to be 27.7 Tg CO2 Eq (US-EPA, 2011b). Conservation tillage, particularly 

in Midwest regions where mineral-based soils prevail, had the highest rates of carbon 

sequestration (US-EPA, 2011b). 

Agriculture-related GHG production will not change significantly unless large amounts of crop 

plantings produce changes in measureable concentrations (USDA-APHIS, 2010b). For example, 

the EPA has identified a net decline in the sequestration of carbon in soil over an 18-year period. 

It attributes this to the impact of the Conservation Reserve Program which encouraged growers 

to take marginal lands out of production (US-EPA, 2011b). To a certain extent, the EPA also 

noted that adoption of conservation tillage resulted in increases in carbon sequestration on those 

croplands (US-EPA, 2011b). The highest rates of carbon sequestration in mineral soils occurred 

in the Midwest, which is the region with the largest area of cropland managed with conservation 

tillage (US-EPA, 2011b). This is in contrast to the highest emission rates from organic soils 

noted in the southeastern coastal region, the areas around the Great Lakes, and the central and 

northern agricultural areas along the West Coast (US-EPA, 2011b). 

5

The global warming potential of greenhouse gases is measured against the reference gas CO2; reported as teragrams 

(millions of metric tons) of CO2 Equivalent, expressed as Tg CO2 Eq.

43

 
One impact of climate change on agriculture is a general increase in the current range of weeds 

and pests; a trend that is expected to continue. Modification of current agricultural practices will 

be required to respond to counter these pests (Field et al., 2007). 

Climate change may have a positive impact on agriculture in general. The Intergovernmental 

Panel on Climate Change (IPCC) predicts that potential climate change in North America may 

result in an increase in crop yield by 5-20 percent during the current century (Field et al., 2007). 

However, the extent of positive effects on agriculture from climate change is highly speculative

and will not be observed in all growing regions. The IPCC report indicates for example that 

certain regions of the U.S. will be impacted negatively by a significant decline in available water 

resources. Nevertheless, North American production is expected to adapt to climate change 

impacts with improved cultivars and responsive farm management (Field et al., 2007).

3.2.7 Land Resources

Land resources are subdivided in this section into land cover and land use. According to the 

Food and Agricultural Organization of the United Nations (FAO), land cover is the observed 

physical cover on the surface of the earth as seen from the ground or through remote sensing. It 

includes vegetation (natural or planted) and human constructions such as buildings and roads

(FAO, 1997).

Land use refers to the function or the purpose for which the land is being used. Therefore, land 

use can be defined as an activity or series of activities undertaken to produce one or more goods 

or services (FAO, 1997). FAO also indicates that a given land use may take place on one or more 

parcels, and several different uses may occur on a single parcel. This definition provides a basis 

for precise and quantitative economic and environmental impact analyses of different uses.

Land cover—Land cover data were obtained for each Level III ecoregion using USDA-NASS 

CropScape (USDA-NASS, 2013i). Statistical data for acreage generated by CropScape tends to 

be low, so estimates should be considered raw numbers requiring a correction factor (USDANASS, 2013i). However, the bias in estimates of area for different land covers is proportionately 

equal, enabling accurate comparisons of the area of different land cover classes relative to each 

other.

NASS uses the 2006 U.S. Geological Survey (USGS) National Land Cover Dataset (NLCD)

(USGS-NLCD, 2006) to help identify non-agricultural land cover (USDA-NASS, 2013i). Table 

4 compares the land cover groups and classes used in NLCD 2006 to those used in this analysis, 

and lists the class number used in each categorization. For definitions of land classes, see NLCD 

(2013).

Table 4. Comparison of NLCD 2006 Land Cover Groups to Classes Used in This EIS

NLCD 2006 This EIS

Water:

Open water (11)

Perennial ice/snow (12)

Water (1)

44
NLCD 2006 This EIS

Developed:

Open space (21)

Low Intensity (22)

Medium Intensity (23)

High Intensity (24)

Developed (2)

Barren (31) Barren (3)

Forest:

Deciduous (41)

Evergreen (42)

Mixed (43)

Forest:

Deciduous (4a)

Evergreen (4b)

Mixed (4c)

Shrubland (52) Shrubland (5)

Herbaceous:

Grassland/Herbaceous (71)

Grassland/Herbaceous (6)

--- Pasture and Hay (7)

(excluding alfalfa)

Planted/Cultivated:

Pasture/Hay (81)

(including alfalfa)

Cultivated Crops (82)

(including orchards;

vineyards)

Cropland:

Orchards

& Vineyards (8a)

Row crops (8b)

(including alfalfa; nonforestry trees)

Fallow (8c)

Wetlands:

Woody (90)

Herbaceous (95)

Wetlands (9)

Land cover composition varies across the affected environment (Table 5). For example, 

developed land ranges from 3 to 17 percent of land cover among the regions, accounting for 10

percent or more of the land cover in regions A, B, C, D, J, K, and M. Central Plains regions H 

and I, and region L in Idaho have much lower amounts of developed land. Wetlands account for 

17 percent of the Mississippi Alluvial region F, and 12 to 14 percent of region B and Coastal 

Regions D and K, but make up much smaller proportions of other regions.

Dominant vegetation types also vary among regions. A summary follows:

Region A: forest is dominant, accounting for nearly 50 percent of land cover, followed by 

pasture/hay and cropland in roughly equivalent amounts (13 to 15 percent).

Region B: forest is slightly dominant, accounting for about 33 percent of land cover, followed by 

cropland at about 27 percent and pasture/hay and wetland at approximately 10 percent each.

Region C: cropland is dominant, accounting for approximately 60 percent of land cover, with 

forest and pasture/hay each covering less land (10 to 12 percent) than developed areas (14

percent).

45
Region D: forest is dominant, accounting for over 40 percent of land cover, followed by cropland 

and wetlands at approximately 15 percent each and the combination of pasture/hay and grassland 

at 12 percent.

Region E: forest is dominant, accounting for about 40 percent of land cover, while cropland and 

pasture/hay each account for approximately 25 percent of land cover.

Region F: cropland is dominant, accounting for slightly under 40 percent of land cover, while 

forest covers 20 percent and wetland covers 17 percent of the region.

Region G: cropland is dominant, accounting for about 55 percent of land cover, while 

pasture/hay and grassland account for about 10 percent each.

Region H: grassland is dominant, accounting for about 55 percent of land cover, while cropland 

accounts for about 30 percent.

Region I: cropland is slightly dominant, accounting for a little over 40 percent of land cover, 

while grassland accounts for 30 percent and pasture/hay for 15 percent.

Region J: grassland is slightly dominant, accounting for about 25 percent of land cover, followed 

closely by cropland at slightly over 20 percent and pasture/hay at slightly over 15 percent.

Region K: cropland and pasture/hay are co-dominant, each accounting for slightly under 25

percent of land cover, followed by shrubland, grassland, and wetland at roughly 12 percent each.

Region L: shrubland is dominant, accounting for over 50 percent of land cover, while cropland 

accounts for about 25 percent; this region is notable for a fairly high level of barren land (about 5

percent) compared to all other regions (1 percent or less).

Region M: cropland is dominant, accounting for nearly 55 percent of land cover, followed by

grassland at about 20 percent of land cover.

Table 5. Land Cover Composition by Region

Land Cover

Composition

Percent* Composition by Region

Region

A B C D E F G H I J K L M

1. Water 3 3 1 2 2 3 2 3 <1 2 2 1 1

2. Developed 12 9 14 11 8 6 7 3 4 17 13 4 11

3. Barren <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 1 4 1

4a. Deciduous 43 30 12 24 38 13 7 1 1 10 2 <1 <1

4b. Evergreen 3 2 <1 16 1 5 <1 <1 <1 1 1 1 <1

46
Land Cover

Composition

Percent* Composition by Region

Region

A B C D E F G H I J K L M

4c. Mixed 3 1 <1 1 <1 2 <1 <1 <1 <1 <1 <1 <1

5. Shrubland 3 1 <1 4 <1 5 <1 <1 6 4 12 52 <1

6. Grassland 1 5 1 4 1 <1 11 56 30 26 11 2 20

7. Pasture/hay 15 10 10 8 23 11 13 5 15 17 23 10 1

8a. Orchards <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 22

8b. Row crops 12 27 59 13 25 34 56 29 36 21 18 23 22

8c. Fallow 1 <1 <1 2 <1 4 <1 1 6 1 5 2 10

9. Wetlands 3 12 2 14 1 17 4 2 1 2 13 1 2

*Rounded to nearest whole percent; totals may not add to 100 percent because of rounding errors. Source: USDANASS CropScape land cover data for 2012 (USDA-NASS, 2013i).

Land Use: This analysis includes details about human interactions with their environment, both 

natural and human-induced. Such analyses address how different land uses interact. It also 

identifies any potential conflicts between current and new land uses. 

The major land uses of the affected environment are agriculture (including crop cultivation, 

pasture and rangeland, animal production, forestry and logging), industrial, housing/residential 

(including urban, suburban and rural), and recreational and tourism. However, the relative 

proportions of major land uses vary between and within regions. Table 6 shows the major crops 

grown in each region (excluding hay). Data on animal production is from the 2007 Census of 

Agriculture (USDA-NASS, 2009e).

Region A: Principal crops include corn, soybean, and alfalfa. Grain production is primarily for 

dairy cattle. Hay exceeds corn production acreage by 40 percent. Orchards, vineyards and row 

crops are also important in New York. Surface and underground coal mining (USGS, 2013a),

and logging are important in parts of western Pennsylvania. As a result, sedimentation and 

acidification of surface waters are serious environmental problems. Compared with other U.S. 

regions, there is a relatively high density of road networks, which is consistent with current nonagricultural and non-mineral land-use patterns in the region: industrialization, urbanization, and 

development for recreation and tourism.

Region B: Agricultural uses include cultivated cropland, pasture, livestock and dairy farming. 

Corn, soybean, and alfalfa are the principal crops, along with some wheat. Dry beans, potatoes, 

vegetables, cherries and other fruits are important crops in the eastern part of the region. Dairy 

farming is prevalent in Wisconsin. Other important land uses are recreation and tourism, and 

mineral extraction, including peat harvesting, and industrial sand and gravel mining (USGS, 

2013a).

47
Region C: Most land use devoted to agriculture and cropland is extensive throughout the region. 

The predominant crops are corn and soybeans. Less important crops include wheat, alfalfa, dry 

beans, and squash. In Wisconsin most of the cropland is devoted to forage and feed grains to 

support dairy operations. Livestock and egg production are also common. There are several large 

urban and industrial centers. Smaller urban, suburban and rural residential land uses occur

throughout the region.

Region D: Land use in the north is primarily for agriculture or urban and suburban industrial use. 

Feed and forage crops and soybeans are prevalent. Nurseries for horticultural products and 

Christmas tree farms occupy some areas. The remainder of the region includes a mosaic of

cropland, pasture, woodland and forests. Pine plantations are particularly prevalent to the south. 

Predominant crops in the region are soybean, corn, cotton, wheat, and peanuts. Other important 

crops include tobacco, pecans, sweet potatoes, peaches, and watermelon. Hay production areas 

are approximately equivalent to that for corn. There is also a high density of poultry and hog 

production in some parts of the region. Land use in coastal areas within the region is

characterized by a high density of urban and suburban development with recreation and tourism.

Region E: Land use in the north and west is dominated by cropland agriculture and pasture. The 

east and south tends to have a higher diversity of land uses that includes cropland, pasture, forest, 

and woodlots with some expanding urban areas. Corn and soybean are the predominant crops. 

Wheat is also an important crop in the region, and tobacco is a significant crop in Kentucky. 

Livestock production, poultry farming and egg production are also common. Mineral extraction 

is important in some parts of the region. This includes some oil and gas production in the south 

and east. Surface and underground coal mining are important industries in western Kentucky, 

southern Illinois and Indiana (USGS, 2013a), and these areas are associated with significantly 

degraded downstream wetland habitat and water quality.

Region F: Except for the southern-most portion of the Mississippi Alluvial Plain (8.5.2), most of 

the region is cropland or pasture. Soybean is the predominant crop. Rice is another major crop. 

More than 70 percent of U.S. rice is produced in this region. Other important crops include corn, 

cotton, wheat, sugarcane, and sweet potatoes. About 85 percent of U.S. aquaculture is conducted 

in this region. Principal products are catfish and crawfish from commercial ponds. Important 

minerals are ball clay mined in western Kentucky and Tennessee (USGS, 2013a), and oil and gas 

production in the southern part of the region.

Region G: This is one of the most productive agricultural areas in the world. Cropland is 

extensive, exceeding 75 percent of land use in some parts of the region. Principal crops are corn 

and soybean. Other important crops include wheat, rapeseed, sunflower, hay and alfalfa, sugar 

beets, dry beans and peas, and flaxseed. Hog, cattle, and egg production are also significant 

important.

Region H: The primary land uses in this region are rangeland for cattle grazing and cropland. 

The dominant crop is wheat. Other major crops are corn, soybean, sunflower, rapeseed, alfalfa, 

buckwheat, flaxseed, lentils, and peas. Hay production acreage is about 85 percent of that used in 

corn production.

48
Region I: Cropland (dryland and irrigated) and rangeland for cattle grazing are the principal land 

uses. Wheat and corn are the primary crops. Cotton, soybean, sorghum, millet, alfalfa, and 

triticale are also important. Cattle production and, in a few areas hog production, are also 

common. Mineral resources, primarily oil and gas, are also important in some parts of the region.

Region J: Most of the region is devoted to cropland, pasture, rangeland, and urban uses. Major 

crops include wheat, corn, sorghum, cotton and oats. Cropland in many parts of the region is 

under pressure from development into urban, suburban and industrial uses.

Region K: Much of the region is cropland. Sorghum is the dominant crop. Cotton, corn, rice, and 

citrus are also important. Grasslands and shrub rangeland provide fodder for livestock grazing. 

Salt (USGS, 2013a), oil and gas are important mineral production activities. Increased 

urbanization and industrialization are recent trends in the region.

Region L: A large percent of the alluvial valleys bordering the Snake River are in irrigated 

agriculture. Principal crops include alfalfa, wheat, barley, corn, and potatoes. Sugar beets, 

turnips, and other vegetables are also important. Cattle feedlots and dairy operations are also 

common and sagebrush-grasslands provide rangeland for grazing.

Region M: Land use is dominated by agriculture. Nearly half the land in the region is cropland. 

Three quarters of it is irrigated. A very wide variety of crops are grown. The major crops by land 

area are almonds, alfalfa, wheat, grapes, corn, and rice. Other major crops, often constituting 

over 50 percent of U.S. production, include walnuts and pistachios, tomatoes, fruits (plums, 

nectarines, pomegranates, apricots, pears, peaches, cherries, and citrus), olives, garlic, melons, 

vetch, clover and wildflowers, safflower, lettuce, and onions. Cattle and dairy production, largely 

feedlot-based, are also major agricultural activities. Urban areas and oil and gas production are 

also important. Wildlife habitat loss and urban sprawl are environmental concerns.

Table 6. Major Cultivated Crops by Region in 2012

Region Crop*

Cropland:

As a Percent 

of Total 

Cropland 

Acreage in the 

Region§

In Region As 

a Percent of 

Total U.S. 

Acreage

A Corn

Soybean

Alfalfa

Wheat

Oats

Cabbage

51%

20%

20%

3%

2%

<1%

3%

1%

6%

<1%

5%

44%

B Corn

Soybean

Alfalfa

51%

25%

16%

9%

6%

17%

49
Region Crop*

Cropland:

As a Percent 

of Total 

Cropland 

Acreage in the 

Region§

In Region As 

a Percent of 

Total U.S. 

Acreage

Wheat

Dry Beans

Asparagus

Cucumbers

Cherries

Celery

Squash

4%

1%

<1%

<1%

<1%

<1%

<1%

1%

10%

55%

41%

36%

29%

28%

C Corn

Soybean

Wheat

Alfalfa

Dry Beans

Cucumbers

Gourds

Pumpkins

53%

40%

3%

2%

<1%

<1%

<1%

<1%

18%

17%

2%

4%

9%

47%

33%

30%

D Soybean

Corn

Cotton

Wheat

Peanuts

Tobacco

Pecans

Sweet Potatoes

Peaches

Watermelon

Christmas Trees

33%

33%

18%

15%

7%

1%

2%

<1%

<1%

<1%

<1%

6%

4%

17%

3%

55%

84%

59%

43%

37%

32%

26%

E Corn

Soybean

Wheat

Cotton

Alfalfa

Gourds

52%

46%

7%

1%

<1%

<1%

8%

9%

2%

1%

<1%

59%

F Soybean

Corn

Cotton

Rice

51%

20%

12%

11%

12%

4%

15%

70%

50
Region Crop*

Cropland:

As a Percent 

of Total 

Cropland 

Acreage in the 

Region§

In Region As 

a Percent of 

Total U.S. 

Acreage

Wheat

Sweet Potatoes

Sugarcane

10%

<1%

1%

3%

36%

22%

G Corn

Soybean

Wheat

Alfalfa

Canola

Sugar beets

Dry beans

Flaxseed

45%

40%

8%

2%

1%

1%

1%

<1%

34%

39%

11%

8%

61%

54%

41%

37%

H Wheat

Corn

Soybean

Sunflower

Alfalfa

Buckwheat

Flaxseed

Lentils

40%

23%

14%

8%

4%

<1%

1%

1%

9%

3%

2%

60%

3%

60%

57%

29%

I Wheat

Corn

Cotton

Soybean

Sorghum

Millet

Triticale

38%

28%

12%

11%

8%

1%

<1%

29%

12%

37%

6%

51%

67%

29%

J Wheat

Corn

Sorghum

Cotton

Oats

38%

26%

18%

8%

7%

2%

1%

5%

1%

10%

K Sorghum

Cotton

Corn

Rice

Citrus

48%

26%

13%

6%

6%

19%

5%

<1%

6%

9%

51
Region Crop*

Cropland:

As a Percent 

of Total 

Cropland 

Acreage in the 

Region§

In Region As 

a Percent of 

Total U.S. 

Acreage

L Alfalfa

Wheat

Barley

Corn

Potatoes

Turnips

31%

20%

14%

12%

10%

<1%

6%

1%

15%

<1%

30%

45%

M Almonds

Alfalfa

Wheat

Grapes

Corn

Walnuts

Plums

Tomatoes

Pomegranates

Olives

Nectarines

Garlic

Pistachios

Honeydew Melons

Apricots

Cantaloupes

Vetch

Clover/Wildflowers

Pears

Safflower

Lettuce

Rice

18%

12%

11%

10%

10%

5%

1%

5%

<1%

1%

<1%

<1%

3%

<1%

<1%

<1%

<1%

1%

<1%

1%

<1%

9%

93%

5%

1%

54%

1%

98%

95%

91%

90%

89%

84%

84%

75%

56%

45%

43%

39%

36%

34%

34%

32%

22%

*Statistics for hay not included. §

Some regional totals may be less than 100 percent because of rounding errors,

or greater than 100 percent because of double cropping practices.

3.3 Biological Resources

3.3.1 Animal Communities

Animal communities in this discussion include wildlife species and their habitats. Wildlife refers 

to both native and introduced species of mammals, birds, amphibians, reptiles, invertebrates, and 

52
fish/shellfish. Wildlife may feed on soybean and corn in the field and/or utilize habitat 

surrounding fields for nesting and refuge. Mammals and birds may seasonally consume soybean 

and corn, and invertebrates can feed on the plant during the entire growing season. How 

agricultural and other lands are managed influences the function and integrity of ecosystems and 

the wildlife populations that they support. 

Mammals, Birds, and Reptiles

Several mammals are widespread through many or most of the affected environment. These 

include white-tailed deer (regions A-I; K), mule deer (regions L and M), coyotes (regions A-C;

G-M), foxes (regions A-G; I), raccoons (regions A-G; J), red and/or gray squirrels (regions A-D;

F-H), bobcats (regions C-F; H-L), and cottontail rabbits and/or jackrabbits (regions D; G-J, M). 

Other common or characteristic mammals are more localized:

• Region A: black bear, chipmunk, woodchuck, wolf in northern areas, beaver in the south

• Region B: beaver, otter, mink

• Region D: black bear, chipmunk

• Region E: badger, weasel in the north and west

• Region G: badger and skunk in southern areas

• Region H: pronghorn antelope and prairie dogs

• Region I: pronghorn antelope

• Region J: ringtail cat, armadillo, skunk, gopher

• Region K: ringtail cat, armadillo, ocelots

• Region L: pronghorn antelope, elk, cougar, chipmunk, pika, bats

• Region M: pronghorn antelope, elk, kit fox, ground squirrels, kangaroo rat

Common or characteristic birds and reptiles include:

• Region A: wild turkey, waterfowl, ruffed grouse, woodpecker, warbler, screech owl

• Region B: wild turkey, turkey vulture

• Region C: Canada goose, sandpiper, sparrow

• Region D: wild turkey, herons, cardinal, box turtle, garter snake, rattlesnake

• Region E: cardinal, bobwhite quail, Carolina chickadee, snapping and box turtles, 

rattlesnake, copperbelly water snake

• Region F: wild turkey, migratory waterfowl, mourning dove, Carolina wren, wood 

thrush, cormorants, egrets, herons; widespread loss of forest and wetland habitat, has 

reduced bird populations but this region remains a major migration corridor

• Region G: this region is a major breeding habitat for waterfowl and other birds, including 

Canada goose, bobwhite quail, sharp-tailed grouse, and pheasants

• Region H: golden eagle, ferruginous hawk, sage grouse, rattlesnakes

• Region I: numerous waterfowl migrate along this region

53
• Region J: turkey vulture, Texas horned lizard

• Region K: waterfowl, geese, oriole, prairie chicken, alligator

• Region L: migratory waterfowl, chickadee, falcon, raven, thrasher

• Region M: wintering waterfowl, Nuttall’s woodpecker, yellow-billed magpie, giant garter 

snake

Cornfields are generally considered poor habitat for birds and mammals in comparison with 

uncultivated lands, but the use of cornfields by birds and mammals is not uncommon. Some 

birds and mammals use cornfields at various times throughout the corn production cycle for 

feeding and reproduction. Most birds and mammals that utilize cornfields are ground foraging 

omnivores that feed on corn seed, sprouting corn, and the corn remaining in the fields following 

harvest.

The types and numbers of birds that inhabit cornfields vary regionally and seasonally, but 

numbers are general low (Patterson & Best, 1996). Bird species commonly observed foraging on 

corn include red-winged blackbird (Agelaius phoeniceus), horned lark (Eremophila alpestris), 

brown-headed cowbird (Molothrus ater), vesper sparrow (Pooecetes gramineus), ring-necked 

pheasant (Phasianus colchicus), wild turkey (Meleagris gallopavo), American crow (Corvus 

brachyrhynchos), and various grouse and quail species (Dolbeer, 1990; Mullen, 2011; Patterson 

& Best, 1996). Following harvest, it is also common to find large flocks of Canada goose

(Branta canadensis), snow goose (Chen caerulescens), Sandhill cranes (Grus canadensis), and 

other migratory waterfowl foraging in cornfields (Sherfy et al., 2011; Sparling & Krapu, 1994; 

Taft & Elphick, 2007).

Large- to medium-sized mammals that are common foragers of cornfields include: white-tailed 

deer (Odocoileus virginianus), raccoon (Procyon lotor), feral hogs (Sus scrofa), and woodchuck 

(Marmota monax). The most notable of these are the white-tailed deer which often inhabit 

woodlots adjacent to cornfields and frequent these fields for both food and cover, especially in 

mid-summer (Vercauteren & Hygnostrom, 1993). White-tailed deer are considered responsible 

for more corn damage than any other wildlife species (Stewart et al., 2007). Cornfields are 

vulnerable to deer damage from emergence through harvest (Vercauteren & Hygnostrom, 1993), 

but any damage at the tasseling stage most directly impacts yield (Stewart et al., 2007). In 

addition to deer, significant damage to corn by raccoons also has been documented (Beasley & 

Rhodes, 2008; DeVault et al., 2007). Corn has been shown to constitute up to 65 percent of the 

diet of raccoons during the late summer and fall (MacGowan et al., 2006).

Small mammal use of cornfields for shelter and forage also varies regionally and includes the 

deer mouse (Peromyscus maniculatus), meadow vole (Microtus pennsylvanicus), house mouse 

(Mus musculus), and the thirteen-lined ground squirrel (Spermophilus tridecemlineatus) 

(Nielsen, 2005). Throughout the U.S., the deer mouse is the most common small mammal in 

agricultural fields (Stallman & Best, 1996; Sterner et al., 2003). Deer mice have been considered 

beneficial in agroecosystems because they consume both weed and insect pests in addition to 

seeds (Smith, 2005). The meadow vole feeds primarily on fresh grass, sedges, and herbs, and 

also on seeds and grains of field crops. Although the meadow vole may be considered beneficial 

as a consumer of weeds, this vole can be a significant agricultural pest where abundant when it 

54
consumes seeds in the field. Meadow vole populations are kept in check by high intensity 

agriculture methods, including conventional tillage; this vole is often associated with cover 

surrounding the edge of field, and in limited tillage agriculture and strip crops (Smith, 2005). The 

lined ground squirrel feeds primarily on seeds of weeds and available crops, such as corn and 

wheat. This species has the potential to damage agricultural crops, but can also be beneficial by 

eating pest insects, such as grasshoppers and cutworms (Smith, 2005).

Animals that feed primarily on soybean are seed-feeding insects and rodents found in 

agricultural fields. Rodents, such as mice or squirrels, may seasonally feed exclusively on 

soybean seeds. During the winter months, leftover and unharvested soybeans provide a food 

source for wildlife. White-tailed deer and groundhogs cause feeding damage on soybeans. 

Eastern cottontail, raccoon, Canada goose, squirrels, and other rodents (such as ground squirrel) 

also feed on soybean, but cause little damage (MacGowan et al., 2006).

Deer in large numbers may significantly damage soybean in site-specific circumstances by 

browsing in soybean fields for forage. In some areas, growers may be issued licenses to kill deer 

outside the regular hunting season to reduce crop damage (Berk A, 2008; Garrison & Lewis, 

1987). Deer may also feed on seed left after harvest. In Georgia, feral hogs have also damaged 

soybean fields through rutting and feeding (GDNR, 2003). It is likely that reptiles and 

amphibians may also be found in soybean fields, especially if the habitat surrounding the field is 

suitable to support these types of animals. 

Migratory birds were observed to feed on spilled soybean following crop harvest (Galle et al., 

2009), although more birds fed on nearby corn and sunflower seed fields. As many as 28 

desirable (not crop pest) bird species, as well as another five that can be crop pests in sunflower, 

have been identified as resident in soybean and corn fields in the Dakotas (Gamble et al., 2002).

Invertebrate Communities

Although many arthropods in agricultural settings are considered pests, such as the European 

corn borer (Ostrinia nubilalis) and the corn rootworm (Diabrotica spp.)(Willson & Eisley, 

2001), there are many beneficial arthropods which are natural enemies of both weeds and insect 

pests(Landis et al., 2005). Some of these beneficial species include the convergent lady beetle 

(Hippodamia convergens), carabid beetles, the caterpillar parasitoids (e.g., Meteorus communis

and Glyptapanteles militaris), and the predatory mite (Phytoseiulus persimilis)(Shelton, 2011).

Some of the many insects and invertebrates that are detrimental to soybean include: bean leaf 

beetle (Cerotoma trifurcata), beet armyworm (Spodoptera exigua), blister beetle (Epicauta spp.), 

corn earworm (Helicoverpa zea), grasshopper (Acrididae spp.), green cloverworm (Hypena

scabra), seed corn beetle (Stenolophus lecontei), seedcorn maggot (Delia platura), soybean 

aphid (Aphis glycines), soybean looper (Pseudoplusia includens), soybean stem borer (Dectes 

texanus), spider mites (Tetranychus urticae), stink bug (green [Acrosternum hilare]; brown 

[Euschistus spp.]); and velvetbean caterpillar (Anticarsia gemmatalis) (Palmer et al., No Date; 

Whitworth et al., 2011).

Aquatic Animal Communities

55
Common fish include:

• Region A: northern pike, walleye, carp, bass, trout

• Region B: trout, perch, catfish

• Region F: alligator gar, pallid sturgeon, other “big river” species

• Region G: walleye, perch

• Region L: trout

• Region M: Chinook salmon, delta smelt

Aquatic ecosystems potentially impacted by agricultural activities include water bodies adjacent 

to or downstream from crop field, including impounded bodies, such as ponds, lakes, and 

reservoirs, and flowing waterways, such as streams or rivers. If near coastal areas, aquatic 

habitats affected by agricultural production may also include marine ecosystems and estuaries. 

Aquatic species that may be exposed to sediment from soil erosion and, nutrients and pesticides 

from runoff and atmospheric deposition include freshwater and estuarine/marine fish and 

invertebrates, and freshwater amphibians. Although some ecological research has shown that 

farming practices can be detrimental to stream health (Genito et al., 2002), recently some 

research suggests that agricultural lands may support diverse and compositionally different 

aquatic invertebrate communities when compared to nearby urbanized areas(Lenat & Crawford, 

1994; Stepenuck et al., 2002; Wang et al., 2000).

3.3.2 Plant Communities

Plant communities vary by region. Table 5 describes land cover in each of the regions. The types 

of plants vary with the land cover. As described on page 44, vegetation can include forest, 

shrubland, cropland, pastures, and grasslands. 

Dominant vegetation types among regions are summarized in section 3.2.7. 

Weeds of corn and soybean are also plants found within the corn and soybean growing regions. 

These weeds are identified in Appendix A.3.

56
4 POTENTIAL ENVIRONMENTAL CONSEQUENCES

This chapter examines the effects of four alternative actions on Natural and Biological 

Resources, Socioeconomic effects and Human Health. In this chapter, APHIS only examines the 

direct and indirect effects of its action on the regulatory status of the plants. While we recognize 

that the plants were engineered to be resistant to the application of certain herbicides, those 

herbicides are not currently labeled for use on DAS-40278-9 corn, DAS-68416-4 soybean, or 

DAS-444Ø6-6 soybean. We do not examine the effects of our action combined with future 

actions that may be taken by other Agencies in this chapter. The EPA is currently evaluating the 

use of certain herbicides on these plants. APHIS considers the potential cumulative effects of

herbicide use for the alternatives, if the EPA should take that action in the future, on these same 

resource areas in Chapter 5.

4.1 No Action Alternative

The No Action Alternative represents the status quo, i.e. the situation that would occur if APHIS 

denies the three petitions (see Section 2.1). Under the No Action Alternative APHIS would not 

approve the petitions. Nevertheless, over ninety percent of the corn and soybean crop would 

continue to be GE varieties that have previously been approved for planting and represent the 

status quo. This section describes the effects that are currently occurring on natural and 

biological resources and the interrelated social and economic effects. The analysis examines the 

effects of soybean and corn production on natural and biological resources to allow for a 

comparison for APHIS’ Action Alternatives which would allow for the introduction of new 

soybean and corn varieties. 

4.1.1 Socioeconomic and Human Health

Land Use

Over the last two decades there has been an increase in the acres planted to both corn and 

soybeans. The combined acreage has increased by nearly a third. Many factors have influenced 

the overall increase in acres planted.

Since 2006, U.S. corn planted acreage has increased as market prices have favored the planting 

of corn over alternative crops (USDA-NASS, 2010b; 2011a). The increase in corn acreage has 

been linked to the increase in demand for corn as a feed stock for ethanol production (Hart, 2006; 

USDA-ERS, 2010c). The increase in acreage has involved all varieties of corn and is occurring 

throughout the corn growing areas (USDA-ERS, 2010c).

From 2000 to 2009, many U.S. cotton growers increased production of corn and soybean 

because of favorable prices (USDA-ERS, 2009b). The increase in production of these crops has 

been accompanied by decreases in other crops, including upland cotton, corn grown for silage, 

spring and specialty wheat, and oats (USDA-ERS, 2011c).

57
Corn acreage planted was projected to reach a peak in 2012, with 94 million acres planted 

(USDA-OCE, 2011a). However, in 2012, actual acreage planted was 97.2 million acres and, in 

2013, acreage planted continued to increase to 97.4 million acres (USDA-NASS, 2013e). 

Regionally, Regions G and I (see Figure 1) accounted for the majority of the acres of both corn 

and soybean added in the past 20 years. These same regions saw a decrease in wheat and small 

grains and hay production acres (NASS 2013). One study asserts that over 1 million acres of

grass-dominated land cover in areas of North Dakota, South Dakota, Nebraska, Minnesota, and 

Iowa, were converted to corn and soybean production (Wright & Wimberly, 2013). Grassdominated lands include native prairie, grass and agricultural grasslands such as pasture, hay

lands, and retired cropland converted to perennial grasses through the Conservation Reserve 

Program (CRP). Because hay production and CRP lands have declined in the past decade 

((USDA-ERS, 2012c; USDA-NASS, 2013d) while cropland totals have remained fairly constant 

(USDA-NASS, 2013d), it is likely that the reported reduction in grass lands is primarily from 

conversion of agricultural grasslands to corn and soybean production as opposed to the 

conversion of native grasslands into new agricultural land. 

The demand for corn production under the No Action Alternative is expected to mirror the most 

recent USDA projections which predict a decline in corn from 97 million acres to just under 92 

million acres in 2014 and a further decline to 88.5 million acres through 2023 (USDA-OCE, 

2014). The decrease in overall corn acres is expected to come as a result of increases in soybean, 

cotton, rice, and about 2.8 million less planted acres of field crops overall. (USDA-OCE, 2014). 

During the peak demand for corn spurred by demand for corn for ethanol, many growers in the 

Figure 7. Acres of Corn and Soybean Planted in the U.S. 1990-2013

The acreage of both corn and soybean planted over the past two decades has increased. Total 

acreage has increased by approximately 43 million acres or 32 percent. (USDA-NASS, 2013f; g)

50000000

70000000

90000000

110000000

130000000

150000000

170000000

190000000

199019921994199619982000200220042006200820102012

acres

Acres of Corn and Soybean Planted in the 

U.S. 1990-2013

corn acres

soy acres

total acres in corn and soy

58
upper Midwest converted to a three year rotation schedule where consecutive years of corn were 

followed by soybean (Hart, 2006). The decreased demand for corn and the increased demand for 

soybean may reduce the frequency of the three-year rotation of corn in favor of the two-year 

corn/soybean rotation.

Corn currently is produced commercially in 48 states (USDA-NASS, 2011b) . Under the No 

Action Alternative, the number of states involved in corn cultivation is not expected to change

over the next decade. However, the amount of corn cultivated in each state may change.

From 1990 to 2013, acreage planted with soybean increased from 59 million acres to greater than 

77 million acres (Figure 7); the second most widely planted crop in the U.S., behind corn. The 

increase in soybean acreage was related to strong prices, the absence of acreage set-aside 

programs, increased crop rotations with soybeans, and optimum soybean planting conditions. 

The elimination of nearly all supply controls on U.S. field crop production by the 1996 Farm Bill 

allowed farmers to increase soybean acreage in response to market signals. A sharp increase in 

soybean acreage between 1996 and 2001 is attributed to low production costs, at least partially 

due to the adoption of HR varieties and conservation tillage practices (Foreman & Livezey, 

2002). The most recent USDA projections are for soybean plantings to increase slightly through 

2020 (USDA-OCE, 2014) and this projection is expected to continue under the No Action 

Alternative. 

Soybeans are widely grown in the U.S., the top five producing states (Iowa, Illinois, Minnesota, 

Indiana, and Nebraska) accounted for just more than half of the total U.S. crop in 2012 (USDANASS, 2013c). 

In summary, the trend to increase the land used for corn at the expense of other agricultural land 

is expected to end under the No Action Alternative. Soybean production is expected to increase 

slightly and overall field crop production is expected to decline. 

Domestic Use of Corn and Soybean in the U.S. Economy

In 2013, U.S. growers planted 97.4 million acres of corn, representing the highest planted 

acreage ever (USDA-NASS, 2013b). U.S. corn growers are expected to produce a record-high 

13.9 billion bushels of corn in 2013, up 29 percent from drought-hit 2012 (USDA-NASS, 

2013h). As of January 2014, NASS estimated the 2013/2014 corn yield at 155.8 bushels per acre 

(USDA-NASS, 2014b). The price of corn was $4.50 per bushel(USDA-NASS, 2014c), well 

below the 2012-2013 price of $6.90 per bushel and the price of $6.22 per bushel for 2011/2012 

(Doran, 2013). Despite increased demand for corn for ethanol and exports (Figure 8), increased 

production in the Central Plains and South has increased supplies (Doran, 2013). The per bushel 

price of corn over the last ten years is shown in Figure 9. 

“Corn has food, feed, and industrial uses (Figure 8). It is a major component of livestock feed. 

Feed use, a derived demand, is closely related to the number of animals (cattle, hogs, and 

poultry) that are fed corn. The amount of corn used for feed also depends on the crop's supply 

and price, the amount of supplemental ingredients used in feed rations, and the supplies and 

prices of competing ingredients.

59
As ethanol production increases (Figure 8), the supply of ethanol co-products will also increase. 

Both the dry-milling and wet-milling methods of producing ethanol generate a variety of 

economically valuable co-products, the most prominent of which is distillers dried grains with 

solubles (DDGS), which can be used as a feed ingredient for livestock. Each 56-pound bushel of 

corn used in dry-mill ethanol production generates about 17.4 pounds of DDGS. In the U.S., 

cattle (both dairy and beef) have been the primary users of DDGS as livestock feed, but larger 

quantities of DDGS are making their way into the feed rations of hogs and poultry.

Corn is also processed for human consumption and other industrial uses. Currently food, seed, 

and industrial uses of corn account for about one-third of domestic utilization and this 

distribution is expected to continue under the No Action Alternative. During processing, corn is 

either wet or dry milled depending on the desired end products:

• Wet millers process corn into high-fructose corn syrup glucose and dextrose, starch, corn 

oil, beverage alcohol, industrial alcohol, and fuel ethanol. 

• Dry millers process corn into flakes for cereal, corn flour, corn grits, corn meal, and 

brewer’s grits for beer production. 

The market for food made from corn has grown in recent years with the expanding Latin 

American population in the U.S. Under the No Action Alternative, food uses for corn are 

expected to expand at the rate of population growth. Research is continuing to expand the 

various industrial uses for corn and corn byproducts.

(http://www.ers.usda.gov/topics/crops/corn/background.aspx)

Figure 8. U.S. Domestic Corn Use

60
U.S. soybean production totaled 3.29 billion bushels in 2013, up 8 percent from last year. NASS 

estimated that 75.9 million acres of soybeans were harvested in 2013 (USDA-NASS, 2014b). 

The production was the third largest on record (USDA-NASS, 2014b). The price per bushel for 

soybeans in 2013 was $12.70/bushel (USDA-NASS, 2014c). The per bushel price of soybeans 

over the last ten years is shown in Figure 9. 

The value of U.S. soybean production for beans was $41.8 billion in 2013, down from $43.6 

billion in 2012 (USDA-NASS, 2014c), this value was 23 percent of the total value of field and 

miscellaneous crops in 2012. The Heartland region (Illinois, Indiana, Iowa, Kentucky, 

Minnesota, Missouri, and Ohio) alone accounted for more than 58 percent of the total U.S. crop 

value in 2012. There is significant variation in yields and costs across soybean production 

regions. In 2013, U.S. soybean yields averaged 43.3bushels/acre, from a low of 25bushels/acre in 

Texas to 53 bushels per acre in Nebraska (USDA-NASS, 2014b). The majority of soybeans are 

used for oil and animal feed. Some soybean oil is used to produce industrial products such as 

inks, crayons, candles, and foam cushions (NC Soybean Producers Association, 2011). Under the 

No Action Alternative, these uses are expected to continue.

Figure 9. Corn and Soybean Price per Bushel

Source:(USDA-ERS, 2013d)

Corn and Soybean Agronomic Practices and Costs of Production

Organic Corn and Soy

Agronomic practices associated with corn and soybean production include several crop 

management systems that are available to producers. Conventional farming covers a broad scope 

of farming practices, including the use synthetic fertilizers and pesticides. Conventional farming 

also includes the use of GE varieties that are no longer subject to the regulatory requirements of 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Dollars Per Bushel

Year

Corn and Soybean Price Received per Bushel by Year- US

Corn Soybean

61
7 CFR part 340 or the plant pest provisions of the PPA. Organic systems exclude certain 

production methods, such as synthetic agricultural inputs and GE crops.

Organic production plans prepared pursuant to the National Organic Program include practical 

methods to protect organically-produced crops from accidental commingling with GE materials. 

Commingling of organic corn with GE corn varieties is a concern because corn naturally crosspollinates (Coulter et al., 2010). Typically, organic growers use more than one method to prevent 

unwanted material from entering their fields, including isolation of the farm; physical barriers or 

buffer zones between organic production and non-organic production; planting border or barrier 

rows to intercept pollen; changing planting schedules to ensure flowering at different times; and 

formal communications between neighboring farms (Baier, 2008; NCAT, 2003; NOAA-NMFS, 

2011). These practices follow the same system utilized for the cultivation of certified seed under 

the AOSCA procedures. During the cultivation period, commingling is managed by 

understanding corn pollen dispersal and maintaining adequate distances between fields (MallorySmith & Sanchez-Olguin, 2010; Thomison, 2009). A minimum isolation distance of 250 feet 

between varieties is recommended, while 700 feet is preferred (Diver et al., 2008). Crosspollination between corn fields can be reduced to 0.5 percent or less with a separation distance of 

984 feet (Place & Goodman, 2011).

Organic corn production begins with certified organically grown seed (Diver et al., 2008). The 

organic farming plan used as the basis for organic certification should include a description of 

practices to be observed during certain farming operations to prevent or reduce the likelihood of 

contamination by unwanted substances like GE pollen or seed (Krueger, 2007; Kuepper, 2002; 

Riddle, 2004; Roth, 2011). Organic farming plans should include how the risk of GE pollen or 

co-mingling of seed will be monitored (NOAA-NMFS, 2011). Co-mingling can occur from 

impure seed, seed admixture, volunteer plants, and residual non-organic seed in equipment, 

vehicles, and facilities (Coulter et al., 2010; Mallory-Smith & Sanchez-Olguin, 2010). Growers 

using organic methods should let neighboring growers know that they are using organic 

production practices and request that the neighbors also help the organic grower reduce potential 

cross-pollination (Krueger, 2007; NCAT, 2003). Although conventional corn yields tend to be 

higher than organic yields, net returns from organic acres continue to be greater than that from 

conventional acres, with a 16 percent premium received for organic growers reported in 2008 

(Coulter et al., 2010; Kuepper, 2002; Roth, 2011). Certified organic corn acreage is a relatively 

small percentage of overall corn production in the U.S. The most current data show 234,470

acres of certified organic corn production in 2011 (USDA-ERS, 2013b). This is 0.26 percent of 

the 91.9 million acres of corn planted in 2011 (USDA-NASS, 2014b).

Thomison and Geyer (Thomison & Geyer, 2011) estimated that approximately 5 percent of the 

total corn acreage, or approximately 4 million acres, was devoted to specialty corn varieties. 

Specialty corn varieties have been developed and marketed as Value Enhanced Corn (USDAFAS, 2004). Varieties cultivated as specialty corn included high oil, white, waxy, blue corn, hard 

endosperm/food grade, high-amylose, high lysine, high oleic oil, low phytate, nutritionally 

enhanced, high extractable starch, high total fermentable (for ethanol), popcorn, pharmaceutical 

and industrial corns, and organic (Thomison, 2011). The leading specialty corn states include 

Illinois, Iowa, Nebraska, and Indiana (Thomison, 2011). The amount of specialty corn produced 

under the No Action Alternative is not expected to change.

62
Similar to the production of conventional seed, industry quality standards for specialty crop 

products have led these seed producers and growers to employ a variety of techniques to ensure 

that their products are not pollinated by or commingled with conventional or GE crops 

(Bradford, 2006). Common practices include maintaining isolation distances to prevent pollen 

movement from other corn sources, planting border or barrier rows to intercept pollen, and 

employing natural barriers to pollen (NCAT, 2003; Wozniak, 2002). No changes in the 

deployment of these practices is expected under the No Action Alternative.

All producers of organic or specialty corn crops must address the potential for cross-pollination

with undesired varieties, which may include GE varieties. Methods such as isolation distances, 

use of border or barrier rows, and differing planting schedules are used by producers of specialty 

crops to prevent unwanted material from entering their fields (Bradford, 2006; NCAT, 2003; 

Roth, 2011; Thomison, 2009; Wozniak, 2002). Several categories of specialty soybeans are 

currently grown in the U.S. and marketed both domestically and internationally. Producers of 

organic and other specialty soybeans currently have production and handling procedures in place 

to ensure that their product meets standards specified either in the USDA National Organic Plan

regulations or through contracts, as relevant. 

APHIS recognizes that producers of non-GE corn and soybean, particularly producers who sell 

their products to markets sensitive to GE traits (e.g., organic or some export markets), reasonably 

can be assumed to be using practices on their farm to protect their crop from unwanted 

substances and thus maintain their price premium. As over 90 percent of corn and soybean 

grown in the U.S. is already GE, APHIS will assume as APHIS’ baseline for the analysis of the 

alternatives, that growers of organic corn and soybean are already using, or have the ability to 

use, these common practices. . This view is supported by a comment received from Food and 

Water Watch (APHIS-2013-0042-10152), “a recent survey of certified organic field crop 

producers located mostly in the Midwest found that 95 percent of [organic growers] plant buffer 

crops to protect against genetic contamination at an average annual cost per farm of $4,776 for 

planting, harvesting, storing, and selling buffers to conventional rather than organic markets. 

Three‐quarters of organic corn producers and 78 percent of organic soybean growers delay 

planting to protect against genetic contamination, averaging annual costs of $16,699 for organic 

corn growers and $8,713 for organic soybean producers.” Delayed planting has been used 

successfully by some organic corn producers to control weeds and to avoid potential 

contamination by GE pollen from adjacent fields (NOAA-NMFS, 2011). The late planting 

allows the grower to conduct a secondary tillage pass before planting to control early emerged 

weeds and results in a later silking in the corn flower, thus avoiding pollen contamination from 

GE fields that have been planted earlier (NOAA-NMFS, 2011). The Food and Water Watch 

survey also reports that 59 percent of organic corn growers and 57 percent of organic soybean

producers who have found or suspected “GMO presence” on their farm had grain rejected by a 

buyer. Because the very high baseline of GE corn and soybean grown currently is expected to 

continue under the No Action Alternative, no changes are expected in the amounts of transgenic 

contamination observed in the specialty and organic corn and soybean market under the No 

Action Alternative.

Organic and other non-GE specialty corn and soybeans offer consumers the option of choosing 

non-GE products if that is their preference. The consumer reaction to GE crops since their 

commercialization has been well researched, particularly as to whether consumers would prefer 

63
non-GE and whether they support labeling of foods containing GE ingredients. The hundreds of 

surveys that have been done over the years present contradictory evidence, likely due to 

differences in sampling techniques, the survey instruments used, and the way questions are 

framed (Kalaitzandonakes et al., 2005). Further, preferences expressed in surveys may not be 

consistent with actual purchasing behavior (Fernandez-Cornejo & Caswell, 2006). For example, 

a study of consumers in the Netherlands from 1997 to 2000, a period of time during which GE 

ingredients were required to be labeled and similar products were available to consumers with 

and without GE ingredients, showed no significant changes in purchasing behavior with respect 

to the GE-labeled products despite an increasingly negative public sentiment against them

(Kalaitzandonakes et al., 2005). Under the No Action Alternative, consumers will still have the 

option of purchasing organic and other non-GE specialty corns and soybeans.

Tillage

Prior to planting, the soil is typically stripped of weeds that would otherwise compete with the 

crop for space, water, and nutrients. Field preparation is accomplished through a variety of 

tillage systems, with each system defined by the remaining crop residue on the field. Crop 

residues are materials left in an agricultural field after the crop has been harvested, including 

stalks and stubble (stems), leaves and seed pods (USDA-NRCS, 2005). These residues aid in 

conserving soil moisture and reduce wind and water-induced soil erosion (Heatherly et al., 2009; 

USDA-ERS, 1997; USDA-NRCS, 2005).

A number of different tillage and planting systems are used in corn and soybean production, 

including primary and/or secondary tillage, or no pre-plant tillage operations (IPM, 2007). 

Conservation and reduced tillage practices include: mulch-till, eco-fallow, strip-till, ridge-till, 

zero-till, and no-till (IPM, 2007). Conventional tillage is associated with intensive plowing and 

leaving less than 15 percent crop residue in the field; reduced tillage is associated with 15 to 30

percent crop residue; and conservation tillage, including no-till practices requiring herbicide 

application on the plant residue from the previous season, is associated with at least 30 percent

crop residue and substantially less soil erosion than other tillage practices (US-EPA, 2010c). 

Increases in total acres dedicated to conservation tillage have been facilitated in part by an 

increased use of herbicide-resistant GE crops, reducing the need for mechanical weed control 

(Towery & Werblow, 2010; USDA-NRCS, 2006b; 2010b). According to USDA Agricultural 

Resource Management Survey (ARMS) data, conservation tillage ranging from no-till to 

reduced-till conserving 15 to 30 percent of residues was used on 75 percent of planted corn acres 

in 2010 (USDA-ERS, 2012).

Conservation tillage, although highly valued as a means to enhance soil quality and preserve soil 

moisture, itself has been identified as a potential challenge for corn disease and pest 

management. The surface residues have been identified as an inoculum source for certain 

disease-causing organisms (Robertson et al., 2009). This is especially a problem for growers 

whose crop rotation includes corn-after-corn with minimal tillage (Robertson et al., 2009). 

Diseases identified as related to corn residues include Anthracnose (caused by the fungus 

Colletotrichum graminicola), Eyespot (caused by the fungus Kabatiella zeae), Goss’s wilt 

(caused by the bacteria Corynebacterium nebraskense), Gray leaf spot (caused by the fungus 

Cercospora zeae-maydis), and Northern corn leaf blight (caused by the fungus 

Helminthosporium turcicum) (Robertson et al., 2009). For each of these diseases, the disease 

agent overwinters in the cool and moist soil, and inoculum from the corn residue then infects the 

64
new year crop (Robertson et al., 2009). Disease control measures include cultivation of resistant 

hybrids, crop rotation, and more careful balancing of conservation tillage with residue 

management (Robertson et al., 2009).

Tillage in soybean production systems is used to prepare a seedbed, address soil compaction, 

incorporate fertilizers and herbicides, manage water movement both within and out of a 

production field, and control weeds (Heatherly et al., 2009). A soybean grower’s choice of tillage 

system may be based on factors such as: crop rotation, soil characteristics, nutrient management, 

herbicide program, planting equipment, and management ability and risk (Randall et al., 2002). 

No-till soybean production is not suitable for all producers or areas. For example, no-till soybean 

production is less successful in heavier, cooler soils more typical of northern latitudes (Kok et 

al., 1997; NRC, 2010).

Introduction of improved herbicides and planters in the mid-1980s facilitated better weed control 

and good seed placement in no-tillage systems, which some farmers began to adopt at that time 

(Owen, 2011; Randall et al., 2002). Adoption of conservation tillage systems in general 

accelerated in the 1990s after soil conservation policy was incorporated into the Food Security 

Act of 1985 (NRC, 2010). The introduction of glyphosate-tolerant soybeans in 1996 fit into the 

ongoing trend of increasing adoption of conservation tillage by allowing growers to control 

weeds effectively with herbicide obviating the need for tillage (Carpenter & Leonard, 1999; 

NRC, 2010).

Between 1996 and 2008, adoption of conservation tillage practices by soybean farmers increased 

from 51 percent to 63 percent, and the adoption of no-till increased from 30 percent to 41 percent 

2013 (CTIC, 2011). In an early study of the relationship between the adoption of herbicidetolerant soybeans and the adoption of conservation tillage practices using data from 1997, 

researchers found that soybean farmers using no-till practices had a higher probability of 

adoption of herbicide-tolerant soybeans. However, adoption of herbicide-tolerant soybeans did 

not appear to affect no-till adoption rates (Fernandez-Cornejo & McBride, 2002). A later study 

using data from 2002 found that farmers who adopted no-till practices were more likely to adopt 

herbicide-tolerant soybeans and that adopters of herbicide-tolerant soybeans were more likely to 

adopt no-till systems (Mensah, 2007). In a study of the long-term relationship between the 

adoption of conservation tillage, adoption of herbicide-tolerant soybeans, and herbicide use

between 1996 and 2006, analysis suggested that herbicide-tolerant soybean adoption induces 

farmers to adopt conservation tillage practices (Fernandez-Cornejo et al., 2002).

Conservation tillage practices vary by region. According to the ARMS database, (USDA-ERS, 

2013a) there are no clear trends in adoption of conservation tillage practices by region over the 

past 15 years. Based on the most recent survey data, in many states the use of conservation 

tillage in corn and soybean exceed that of conventional tillage (Table 7). According to the most 

recent ARMS data, states in regions D, E, C, B, G , H, and I use more no-till in corn and soybean

than conventional tillage (Table 7). Interestingly, in some states no-till is adopted on a greater 

percent of the soybean acres than conventional tillage, but in those same states conventional 

tillage is used on a greater percent of the corn (Table 7; IN, MI, MO). The percent of the crop 

cover planted in corn exceeds soybean in most of the states where conventional tillage is used 

more frequently on corn and no till is more frequently used in soybean, indicating that more 

acres of agricultural land may be in conventional tillage in those states than in no-till production. 

65
Because no till agriculture can reduce soil erosion rates to those close to natural erosion 

(Montgomery, 2007), its use is encouraged. Increases in the use of tillage for HR weed 

management in soybean is occurring in some regions of the U.S. Monsanto submitted to APHIS 

third party proprietary data on tillage trends in support of the NEPA analysis for the 

determination of nonregulated status of Dicamba tolerant soybean and cotton (Dicamba EIS 

Appendix 9). This analysis of tillage practices shows that no-till increased in soybean in all parts 

of the country from 1998-2007 but has decreased from 2007-2012 in the Midwest and the MidSouth, became flat or decreased in the East, became flat in the southeast, and continued to 

increase in the west. In cotton no-till increased in all regions in the country from 1998-2007 but 

decreased from 2007-2012 in the Southeast, the Midwest, the Midsouth, but continued to 

increase in the West. GR weeds are not yet problematic in the west and this remains the only 

area where no-till is still increasing. In areas where GR weeds have become problematic, no-till 

is on the decline or has stopped increasing. The trend in the decline of no-till is significant and 

pervasive throughout the country where glyphosate weeds are prevalent and is expected to 

continue under the No Action Alternative.

Table 7. Tillage Practices by Crop

Tillage Method Soybean Corn

Acres in No-Till 

Exceeds Conventional 

Tillage

Illinois

Indiana

Kansas

Kentucky

Maryland

Michigan

Missouri

North Carolina

Ohio

Pennsylvania

South Dakota

Virginia

Wisconsin

Pennsylvania 

Colorado

Iowa 

Kansas

South Dakota

Kentucky

Nebraska

Acres in Conventional 

Tillage Exceeds Other 

Types of Tillage

Arkansas

Louisiana

Georgia,

Indiana, 

Michigan 

Minnesota 

Missouri

North Dakota

Texas

Wisconsin

Mulch Till Exceeds 

Other Types of Tillage

Iowa

Minnesota

Nebraska

North Dakota

New York

Iowa

Source: (USDA-ERS, 2013a)

66
Crop Rotation

Crop rotation is the successive planting of different crops in the same field over a particular 

period of years. Crop rotation has the two primary goals of sustaining the productivity of the 

agricultural system and maximizing economic returns (Hoeft et al., 2000). Sustaining the 

agricultural system is achieved by rotating crops that may improve soil health and fertility with 

more commercially beneficial “cash crops.” Because soybeans fix nitrogen in soil, the yield of 

some crops following a soybean crop, such as corn or wheat, may increase (Berglund & Helms, 

2003). Moreover, the rotation of crops can effectively reduce disease, pest incidence, weediness, 

and selection pressure for weed resistance to herbicides (Berglund & Helms, 2003; USDA-ERS, 

1997). Crop rotation may also include fallow periods, or sowing with cover crops to prevent soil 

erosion and to provide livestock forage between cash crops (Hoeft et al., 2000; USDA-NRCS, 

2010a). Maximizing economic returns is realized by rotating crops in a sequence that efficiently 

produces the most net returns for a producer over a single- or multi-year period. Many factors at 

the individual farm level affect the crop rotation system chosen, including the soil type present in 

an individual field, the expected commodity price, the need to hire labor, the price of fuel, the 

availability of funding to buy seed, and the price of agricultural inputs (Duffy, 2011; Hoeft et al., 

2000; Langemeier, 1997). Figure 10 shows the cropping patterns of the major crops in the U.S. 

As is evident in the figure, most corn and soybean grown in the U.S. is produced in a cornsoybean rotation. The benefits of corn rotation with, for example, soybean are many and include

(Al-Kaisi et al., 2003):

• Improved yield and profitability of one or both crops;

• Decreased need for additional nitrogen on the crop following soybean;

• Increased residue cover resulting in reduced soil erosion; 

• Mitigation or disruption of disease, insect, and weed cycles;

• Increased soil organic matter;

• Improved soil tilth and soil physical properties; and

• Reduced runoff of nutrients, herbicides, and insecticides.

67
Figure 10. Cropping Patterns for Major Crops

Shows cropping patterns for major crops in the U.S. Source: (USDA-ERS, 2011a)

Since 1991, 75 percent of corn planted acreage has been in some form of rotation (Figure 10)

(USDA-ERS, 2010c). Corn can be grown successfully in a conservation tillage system if rotated 

with other crops such as wheat and soybeans, which will reduce some of the problems 

encountered with conservation tillage (IPM, 2007) mentioned above. 

Crops used in rotation with corn vary regionally and include oats, peanut, soybean, wheat, rye,

and forage (USDA-APHIS, 2010b). 

About 20 to 30 percent of corn farmers grow continuous corn. Consecutive plantings of corn 

frequently require at-planting or pre-plant pesticide treatments to control corn pests and 

68
pathogens as well as supplemental fertilizer treatments (Erickson & Lowenberg-DeBoer, 2005; 

IPM, 2004; Sawyer, 2007; Stockton, 2007). Corn-to-corn rotations also may require a change in 

tillage practices. Corn-to-corn cultivation may produce substantially greater quantities of field 

residue, requiring additional tillage prior to planting (Erickson & Lowenberg-DeBoer, 2005). 

The increased adoption of corn-to-corn rotation, mainly in conventional and GE production 

systems, has been attributed to rising corn demand and prices (Hart, 2006; Stockton, 2007).

Crop rotation is a common practice on U.S. soybean fields. Soybeans are often rotated with such 

crops as corn, winter wheat, spring cereals, and dry beans (OECD, 2000), the selection of which 

varies regionally. Corn is the most commonly rotated crop with soybeans. USDA Agricultural 

Resource Management Survey (ARMS) results for corn and soybean indicate a small increase in 

corn in rotation and continuous corn over the past decade (Ebel, 2012; US-FDA, 2011b). Returns 

for producers from a corn-soybean rotation are variable and depend on the price and projected 

yield of both corn and soybean for an individual operator (Stockton, 2007). Studies have found 

the soybean yield tends to increase under this rotation sequence and is attributed to an effective 

break in the soybean disease and pest cycle (Al-Kaisi, 2011; Nafziger, 2007). Soybean itself may 

be a cover crop in short rotations for its nitrogen contributions (Hoorman et al., 2009). 

Continuous soybean production is sometimes practiced, but yield can be reduced the second or 

later years, and pest and disease incidence may increase (Monsanto, 2010a; Pedersen et al., 

2001).

In a survey of major corn/soybean production states, corn and soybean were alternated on 72 to 

80 percent of acreage, other rotations were grown on 16 to 20 percent of acreage, and soybean 

was grown continuously on 5 to 12 percent of acreage between 1996–2002 (USDA-ERS, 2006). 

In 2006, the last year for which USDA survey data are available, 72 percent of soybean acreage 

was planted on acreage planted to corn in the previous year, soybean (13 percent), cotton (0.5 

percent), small grains (8.1 percent), other crops (5.9 percent) and fallow (0.4 percent) (USDAERS, 2013c).

As noted in section 4.1.1 Land Use, economic factors favoring the planting of soybean and 

cotton over corn may decrease plantings of continuous corn and increase rotation of corn to these 

other crops under the No Action Alternative. Increased diversity in rotation crops has also been 

advocated as a strategy for weed control and potentially might increase under the No Action 

Alternative if weed control options increase in cost as expected (see section 4.1.1. herbicides).

Double-cropping soybeans is also an option to increase returns. Soybean is frequently planted in 

winter wheat stubble to produce a crop in the same growing season. Double-cropping maximizes 

profits if high commodity prices can support it, but careful management to achieve uniform 

stands to sustain high yields is needed: the selection of appropriate varieties, a higher seeding 

rate, closer row spacing, and adequate moisture for germination are important variables affecting 

profitability (McMahon, 2011). 

Use of GE Corn and Soybean

Growers can choose from a large number of corn hybrids produced from traditional breeding or 

GE systems (NCGA, 2009). Like the major commodity crops cotton and soybean, GE varieties 

of corn have been adopted during the past decade. Large-scale field testing of GE crops began in 

the 1980s, but it was not until ten years later the first generation of GE varieties became 

69
commercially available (Fernandez-Cornejo & Caswell, 2006). In 2000, approximately seven 

percent of all corn planted was GE HR, and 25 percent of the total crop was GE (USDA-NASS, 

2006). By 2012, a total of 88 percent of the corn crop was GE. Of that number, 73 percent of the 

U.S. corn crop was GE HR, 67 percent was insect-resistant, and 52 percent of the total crop was 

stacked with both GE herbicide tolerance and insect resistance (USDA-ERS, 2012a).

Since GE soybeans’ initial commercial availability in 1996, their use has expanded to greater 

than 90 percent of the total U.S. soybean acreage (Figure 11). Although other varieties are 

available for selection by growers, the Roundup Ready®, GR varieties continue to dominate the 

market (see, e.g., (Tarter, 2011)). Other cultivated herbicide-tolerant soybeans include the 

LibertyLink® soybean varieties (a GE soybean that is resistant to glufosinate ammonium 

herbicide and was granted nonregulated status in 1996) and STS (a conventionally bred 

sulfonylurea-tolerant soybean first introduced in 1993). As of 2012, 3.9 percent of U.S. soybean 

acres planted were glufosinate-tolerant (US-EPA, 2013c). Additional GE traits, such as 

lepidopteran resistance, high oleic acid content, improved fatty acid profile, isoxaflutole 

resistance, mesotrione resistance, and increased stearidonic acid have nonregulated status

(http://www.aphis.usda.gov/biotechnology/petitions_table_pending.shtml). Of these, at this time, 

only high oleic acid content soybean has been commercialized, in a limited launch. Other GE 

traits with nonregulated status may be made available for commercial production in the future

under the No Action Alternative including resistance to the herbicide dicamba. Under the No 

Action Alternative, GE corn and soybean varieties are expected to still comprise over 90% of the 

corn and soybean planted in the U.S. 

70
Figure 11. Percent Adoption of GE Herbicide-Resistant Corn and Soybean in the U.S.

HR GE corn and soybeans have been widely adopted throughout the major corn and soybean growing regions. Dark blue represents 

greater than 89 percent of the crop acres are planted to an HR GE crop. The hatch marks represent the states in the survey area where 

data is not presented on a state level for GE crop adoption. ERS reports that the average adoption for GE HR corn and HR soybean in

the “other” states as 82 percent and 92 percent respectively (USDA-ERS, 2012a).

71
GR soybeans were first commercialized in 1996, and adoption by growers was rapid, reaching 54 

percent already by 2000 and more than 90 percent by 2007 (USDA-NASS, 2012). While some 

potential herbicide cost savings may have driven adoption, early studies recognized the primary 

reason that growers adopted the technology as the simplicity and flexibility of a weed control 

program that relied heavily on a single herbicide to control a broad spectrum of weeds without 

crop injury or crop rotation restrictions. The increased cost of GE herbicide-resistant seed was 

outweighed by the often lower cost of glyphosate-based weed control programs, although this 

cost advantage was quickly eroded by reductions in the prices of other conventional herbicides. 

The GR soybean weed control program reinforced on-going trends towards post-emergence 

weed control and the adoption of conservation tillage programs (Carpenter & Leonard, 1999). 

For 1997, USDA estimated that herbicide-resistant soybeans led to a 3 percent increase in yields 

and a reduction in weed control costs (including, application, scouting, cultivation, herbicides, 

and technology fees) of $3.50/acre (10.65 percent) in the Heartland (Price et al., 2003).

The simplicity and flexibility of the GR soybean program has resulted in reduced management 

time. The time savings related to adoption of herbicide-resistant soybeans was estimated to be 

14.5 percent in 2002 (Gardner et al., 2009). Off-farm income has been found to be an important 

source of household income for many soybean producers, with approximately two-thirds of 

soybean-growing farm families receiving income from off-farm work (Foreman & Livezey, 

2002). The adoption of GE soybean varieties has been associated with increases in off-farm 

income due to reduced on-farm managerial time requirements. In an analysis of soybean 

producing households between 1996 and 2004, a 16 percent increase in off-farm income was 

associated with a 10 percent increase in the probability of adopting HT soybean (FernandezCornejo, 2007).

The reduction in management time is one of the non-pecuniary benefits that influence farmer 

adoption decisions, but are not direct contributors to increased profits. In a study of GR soybean 

in the U.S. in 2002, nonmarket valuation techniques were used to estimate farmer valuation of 

three non-pecuniary characteristics: increased farmer and worker safety, environmental safety, 

and convenience. Convenience was most highly valued, followed by environmental safety, and 

operator and worker safety (Marra & Piggott, 2006). These results are reinforced by an analysis 

of nationwide survey results from 2007, which found that growers rated characteristics such as 

consistency of control, crop safety, and family and employee health as very important more often 

than herbicide cost. In addition, health and environmental concerns, yield concerns, and 

herbicide-application concerns were found to influence grower decisions (Hurley et al., 2009).

GR crops have been widely adopted because of the benefits they provide to growers, but the 

increasing prevalence of GR weeds threatens the sustainability of these benefits. Herbicideresistant weeds can reduce yields and increase weed control costs. 

States with confirmed GR weeds are shown in Figure 12. The problem is the greatest in the 

Southern States where growing seasons are long. Mississippi has seven GR weed species while 

Missouri and Arkansas each have six. Some states such as Georgia and Alabama are infested 

primarily with a single GR weed, Palmer amaranth, but the infestation is very widespread. Figure 

13 shows the number of weeds species in each state that are resistant to the sites of action in the 

EnlistTM crops: 2,4-D, quizalofop, glufosinate, and glyphosate. With the exception of glyphosate, 

72
relatively few species are resistant to these herbicide sites of action in the US. In any given state 

there is no more than a single resistant species and these biotypes are not widespread (Heap, 

2013b). There is one species resistant to glufosinate and it occurs in Oregon. For 2,4-D, there are 

five states that have a resistant species, Washington, Nebraska, Kansas, Michigan, and Ohio. For 

quizalofop, there are also five states that have a resistant species, Oregon, Idaho, Iowa, 

Mississippi, and Tennessee. HR weeds are discussed more fully in Appendix 6. Under the No 

Action Alternative, the increasing trend in the number of weeds resistant to glyphosate and 

glufosinate is expected to continue. 

73
Oregon

Italian ryegrass

California

Hairy fleabane

Horseweed

Junglerice

Rigid ryegrass

Oklahoma

Horsesweed

Common waterhemp

New Mexico

Palmer amaranth

Nebraska

Horseweed

Giant ragweed

Kochia

Kansas

Common ragweed

Common waterhemp

Giant ragweed

Horseweed

Kochia

North Dakota

Common ragweed

Common waterhemp

Kochia

Missouri

Annual bluegrass

Common ragweed

Common waterhemp

Giant ragweed

Horseweed

Palmer amaranth

Arkansas

Common ragweed

Giant ragweed

Horseweed

Italian ryegrass

Johnsongrass

Palmer amaranth

Minnesota

Common ragweed

Common waterhemp

Giant ragweed

Iowa

Giant ragweed

Common waterhemp

Horseweed

Illinois

Common waterhemp

Horseweed

Palmer amaranth

Louisiana

Johnsongrass

Palmer amaranth

Indiana

Common ragweed

Common waterhemp

Giant ragweed

Horseweed

Ohio

Common ragweed

Giant ragweed

Horseweed

Common waterhemp

Palmer amaranth

Mississippi

Common waterhemp

Giant ragweed

Goose Grass

Horseweed

Italian ryegrass

Palmer amaranth

Johnsongrass

Virginia

Pennsylvania

Maryland

Delaware

New Jersey

Kentucky

Horseweed

Michigan

Palmer amaranth

Horseweed

Tennessee

Giant ragweed

Goose Grass

Horseweed

Palmer amaranth

Common waterhemp

North Carolina

Horseweed

Palmer amaranth

Common ragweed

Glyphosate-Resistant Species 1 2 3 4 5 6 7

Alabama

Georgia

Palmer 

amaranth

Figure 12. Distribution of Glyphosate-resistant Weeds in the U.S. 

Source: WSSA, 2012 (Accessed Dec 14, 2012)

74
Figure 13. Number of Weed Species Resistant to Certain Herbicides in the U.S. by State

75
Agronomic Inputs

Corn and soybean production typically involves the extensive use of agronomic inputs to 

maximize grain yield (Ritchie et al., 2008). Agronomic inputs include fertilizers to supplement 

available nutrients in the soil; pesticides to reduce weed, insect, microbial, and nematode 

populations; and water to ensure normal plant growth and development (Howell et al., 1998; 

IPM, 2007). 

Nutrients/Fertilizer

Given the importance of nutrient availability to corn agronomic performance, fertilization with 

nitrogen, phosphorus, and potassium is practiced widely (Ritchie et al., 2008). In 2010 (the date 

of the last USDA Agricultural Chemical Usage Summary to include corn), fertilizers were 

applied to 97 percent of corn acreage in Program States (USDA-NASS, 2010c). Of the reported 

corn acres, nitrogen was applied to 97 percent of the corn acreage at an average of 78 pounds per 

acre (lb/acre); phosphate was applied to 78 percent of corn acreage at an average rate of 52 

lb/acre; potash was applied to 61 percent of corn acreage at a rate of 73 lb/acre; and sulfur was 

applied to 15 percent of the corn crop at an average rate of 11 lb/acre (USDA-NASS, 2010c). 

Under the No Action Alternative, these fertilizer requirements are unlikely to change from 

current use.

Because soybean is a nitrogen fixer, nitrogen is not as frequently added to soybean fields. A 

2006 survey reported by USDA National Agricultural Statistics Service (NASS) (USDA-NASS, 

2009e) found that among 19 select states, nitrogen was applied to 18 percent of the planted 

soybean acreage in those states at an average rate of 16 lb/acre per year, and phosphate was 

applied to 23 percent of the planted acres at an annual average rate of 46 lb/acre. Potash was 

applied to 25 percent of the planted acreage at an average annual rate of 80 lb/acre, and sulfur 

was applied to 3 percent of the planted acres at an average annual rate of 11 lb/acre (USDANASS, 2009e). Other micronutrient supplements such as zinc, iron, and magnesium were applied 

as needed (NSRL, No Date; USDA-NASS, 2007; Whitney, 1997). Under the No Action 

Alternative, these fertilizer requirements are unlikely to change from current use.

Inoculates

To improve yields by an average of 1 bushel/acre, some growers inoculate soybean with the 

bacteria Bradyrhizobium japonicum (Conley & Christmas, 2005). Historically, a non-sterile peat 

powder applied to the seed at planting had been the carrier for the inoculant into the field. More 

recently, improvements have been made in inoculant manufacturing, such as the use of sterile 

carriers, the addition of adhesives for inoculates to stick to seed, the introduction of liquid 

carriers, the use of concentrated frozen products, the introduction of new organism strains, the 

use of pre-inoculants, and the introduction of inoculants with extended biofertilizer and 

biopesticidal properties (Conley & Christmas, 2005). Industry has approximated that about onethird of U.S. soybean acreage was inoculated in 2009 (Seed Today, 2009). Under the No Action 

Alternative, the use of inoculates is unlikely to change from current use.

76
Insecticides

In addition to herbicides, pesticides can be used in corn production. In 2010, approximately 12

percent of the corn-planted acreage was treated with insecticides, with the most abundantly 

applied being tefluthrin for control of corn rootworm (3 percent); cyfluthrin for corn rootworm, 

earworms and European corn borer (2 percent); lambda-cyhalothrin for European corn borer (2

percent); bifenthrin for grubs, wireworms, seed-corn maggot, and cutworms (2 percent); and 

tebupirimphos for corn rootworm and seed corn maggot (2 percent) (USDA-NASS, 2010b).

A wide variety of pests can hinder soybean production, and many require agricultural pesticidal 

inputs for their control. Several groups and types of insects can feed on the foliage, seed pods 

and roots of the soybean plant, and can reduce yield if not adequately controlled (Lorenz et al., 

2006; Whitworth et al., 2011). A major pest for soybean producers is the soybean nematode that 

has no effective pesticidal treatment, especially the soybean cyst nematode (Nelson & Bradley, 

2003). Nematodes are microscopic organisms that feed on the roots of various plants, including 

soybeans. Several races or different groups of nematodes exist, and their control is difficult. 

Some soybean varieties have resistance to some of the races, but often these resistant varieties 

have yielded less than other commercially available soybean varieties. A combination of crop 

rotation to a non-susceptible host and the use of resistant varieties can help alleviate the problem 

(Nelson & Bradley, 2003).

Insect infestation thresholds have been established to indicate when insecticide applications are 

actually necessary (Higgins, 1997). The thresholds are commonly based on number of insects 

found in field sampling surveys and/or in established standard defoliation thresholds, such as 

those provided by the National Information System of the Regional Integrated Pest Management 

Centers in pest management strategic plans (USDA-AMS, 2011). A 2006 survey (USDA-NASS, 

2009e) found that insecticides were applied to 16 percent of the 72.9 million soybean acres 

planted in surveyed states in 2006. Of the 12 reported insecticides, the three most common—

lambda-cyhalothrin, chlorpyrifos, and esfenvalerate—were applied to 6 percent, 5 percent, and 3 

percent of the planted acres, respectively (USDA-NASS, 2009e). Other methods of addressing 

insect infestations include the introduction of beneficial pests that prey on targeted insects 

obtained from commercial suppliers, as well as crop rotation and tillage as discussed above. 

Under the No Action Alternative, use of insecticides on corn and soybean is unlikely to change 

from current use.

Herbicides

The following section provides a brief background of herbicide use in corn and soybeans in the 

U.S. It is provided to give the context for the analyses related to HR weed selection. For further 

information on these subjects see Appendix 3. Weed Management and Herbicide Use; Appendix 

4: Herbicide Use Trends and Predicted Use on EnlistTM Corn and Soybean; Appendix 5: 

Common Weeds in Corn and Soybean; Appendix 6: Herbicide Resistance; Appendix 7: OffTarget Pesticide Movement; Appendix 8: EPA Assessments of Herbicides Used on DAS Corn 

and Soybean.

Herbicide use in corn differs substantially from that in soybean both in the types of herbicides 

used and the variety of herbicide sites of action (see Appendix 3 and 4). Corn yields are more 

77
negatively impacted by early season weed competition than soybeans. Corn is also planted in 

wider rows than soybeans, and the resulting penetration of light allows weed germination over a 

longer period of time than in soybeans. For these reasons, post emergent applications of 

glyphosate are not as beneficial in corn as they are in soybean. To obtain the best corn yields, 

growers manage weeds with pre-plant or pre-emergent herbicide applications. Historically they 

have used atrazine, and chloroacetamide herbicides such as acetochlor, metolachlor, and more 

recently metolachlor-S. They also relied on both dicamba and 2,4-D. Even after GR corn was 

widely adopted, most corn growers have continued to use residual herbicides (such as atrazine 

and chloroacetamides) followed by application of post emergent herbicides as needed to provide 

good weed control and maximize yield potential. 

In contrast, soybean growers have come to rely almost exclusively on glyphosate for weed 

control. Prior to the adoption of GR soybean, growers relied heavily on ALS and microtubule 

inhibitors. With the adoption of GR soybean, glyphosate was used on greater than 95 percent of 

soybean acreage and for 75% of soybean growers, glyphosate represented the only herbicide site 

of action used. As GR weeds have become more prevalent, the trend among soybean growers is 

to use more sites of action including 2,4-D, chloroacetamides, PPO and ALS inhibitors. There 

has also been an increased adoption of glufosinate resistant soybean varieties resulting in a 

tripling of glufosinate use from 2011 to 2012 (from 1.3 percent of soybean acres to 3.9 percent; 

see Appendix 4). This trend in the increased use of glufosinate is expected to continue under the 

No Action Alternative

As described in more detail in Appendix 4, the trend to use more herbicides with different modes

of action is observed for both corn and soybean. There also has been a trend to use more 2,4-D. 

In 2002, all uses of 2,4-D use was estimated to be 46 million pounds but that increased to 64

million pounds in 2011 (Appendix 4). 2,4-D is widely used for agricultural and industrial 

purposes. In 2011, about 40 percent of 2,4-D was used on crops, 38 percent was used on turf and 

ornamentals, and 22 percent was used on range, pasture and for industrial vegetation 

management such as to control unwanted vegetative growth on utility corridors, rights-of-way, 

roadsides, railroads, cemeteries, non-crop areas, and managed forest. It is also used to control 

aquatic and nuisance weeds, e.g., purple loosestrife (Industry Task Force II, 2005). 2,4-D is very 

widely used for non-agricultural use (see Appendix 4 for more details). Agriculturally, it is used 

on a variety of grass crops including pasture/hay, small grains (spring wheat, winter wheat, rice, 

sorghum, barley, millet, oats), corn, and sugar cane and on nut and fruit tree crops (almonds, 

apples, apricots, cherries, citrus, hazelnuts, nectarines, peaches, pears, pecans, pistachios, plums, 

and walnuts). It is also used as a pre-plant treatment in a number of crops such as soybean and 

cotton. There are at least 33 crops where 10 percent of the crop is sprayed with 2,4-D (see 

Appendix 4). As described in more detail in Appendix 4, 2,4-D use on soybean alone increased 

70 percent from 2008 to 2011. The trend in the increased use of 2,4-D is expected to continue 

under the No Action Alternative.

In selecting an herbicide, a grower must consider, among other factors, whether an herbicide can 

be used on the crop (herbicides are registered by the EPA for specific uses/crops), the potential 

adverse effects on the crop, residual effects that can limit crops that can be grown in rotation, 

effectiveness on expected weeds, and cost. Herbicides have different ways of acting on plant 

physiology (i.e., sites or mechanisms of action) to affect the health of a given plant (see 

78
Appendix 3). Some common sites of herbicide action include auxin growth regulators like 2,4-D; 

amino acid inhibitors such as glyphosate; photosynthesis inhibitors such as atrazine; lipid 

biosynthesis inhibitors like quizalofop; and glutamine synthase inhibitors such as glufosinate 

(UW-NPMP, No Date) and (Appendix 3). Applications of herbicides to a crop may occur preplant (i.e., burndown), pre-emergence, or post-emergence (Schneider & Strittmatter, 2003). 

Herbicide use is not regulated by APHIS but regulated by EPA under FIFRA and its 

amendments.

Weeds have been estimated to cause a potential yield loss of 37 percent in world-wide soybean 

production (Heatherly et al., 2009). Weeds compete with soybean for light, nutrients, and soil 

moisture; can harbor insects and diseases; and also can interfere with harvest, causing extra wear 

on harvest equipment (Loux et al., 2008). In addition to weed density, the time that weeds 

compete with the soybean crop influences the level of yield loss. The later the weeds emerge, the 

less impact they will have on yield. Soybean plants withstand early season weed competition 

longer than corn because the soybean canopy closes earlier (Boerboom, 2000). The extent of 

canopy closure restricts the light available for weeds and other plants growing below the 

soybean. In addition, canopy closure occurs more quickly when soybean is drilled or planted in 

narrow rows (Boerboom, 1999); however, in some studies it has also been observed that, 

depending on factors such as weed species, environmental conditions (i.e., rainfall amounts) and 

soybean cultivar, soybeans are able to compete with weeds with no resulting yield reduction 

(Krausz et al., 2001).

Herbicides have been the primary tactic used to manage weed communities in soybeans since the 

mid-1960s and are likely to continue to be an important feature of row crop weed management 

for the foreseeable future. One study, which examined aggregated data on crop yield losses and 

herbicide use, estimated that even if additional tillage and hand weeding labor replaced the use of 

herbicides, U.S. crop production would decline by 20 percent with a $16 billion loss in value if 

herbicides were not used (Gianessi & Reigner, 2007).

GR crops have become adopted widely since their introduction in the mid-late 1990s for several 

reasons. Glyphosate works non-selectively on a wide range of plant species, is a relatively lowcost herbicide, enhances ‘no-till’ farming practices, and has minimal animal toxicological and 

environmental impacts (USDA-APHIS, 2010a). However, increased selection pressure resulting 

from the wide-spread adoption of GR crops, along with the reductions in the use of other 

herbicides and weed management practices, has resulted in both weed population shifts and 

growing numbers of GR individuals among some weed populations (Duke & Powles, 2009; 

Owen, 2008). 

As herbicide-resistant weeds have become increasingly prevalent, costs of weed control have 

also increased. Extension weed scientists estimate that corn growers with GR weeds may incur 

increased weed control costs of up to $35/acre compared with commonly used glyphosate-based 

programs, primarily due to applying herbicides with an additional mode of action (Carpenter & 

Gianessi, 2010). However, growers may be able to control GR weeds in corn without increasing 

costs, due to the availability of low-cost herbicides such as 2,4-D and dicamba, with efficacy 

against GR weeds such as waterhemp and giant ragweed (Carpenter & Gianessi, 2010).

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Extension weed scientists estimated the increased cost of the additional herbicides needed to 

control GR weeds in soybean to be as much as $42/acre (for Palmer amaranth in Tennessee), 

with most estimates of the increased costs falling in the range of up to $20 to $30/acre (Carpenter 

et al., 2002). These costs will vary depending on the specific weed species present in any

particular field. However, as resistance to glyphosate and other herbicides has developed and 

spread in weed populations, these costs may have increased since these estimates were made. For 

example, there are waterhemp populations in Iowa corn and soybean production fields with 

resistance to five herbicide sites of action (Owen, 2012) and Appendix 4. The continued 

selection of weeds resistant to glyphosate and other herbicides used are expected to continue 

under the No Action Alternative. According to comment APHIS-2013-0042-1911 from a weed 

science expert, “the greatest risk for developing herbicide resistance is actually occurring at this 

moment with the PPO herbicides and glufosinate. These products are being over used as growers 

have no other effective herbicidal options. New technologies such as dicamba or 2,4-D could be 

used to delay resistance development to the PPO herbicides and glufosinate. As such crop 

management practices will require modifications to address these weeds. These include

management practices including the use of alternative herbicides for weed control, as well as 

mechanical cultivation practices, and crop rotation.”

Recent work in Australia is leading the development of new technologies that utilize nonchemical weed control strategies that destroy weed seeds during commercial grain harvest 

thereby facilitating weed seedbank decline (Walsh & Newman, 2007; Walsh et al., 2013; Walsh 

& Powles, 2007; Walsh et al., 2012). These technologies have been named harvest weed seed 

control (HWSC) and include systems such as chaff carts, narrow windrow burning, bale direct, 

and the Harrington Seed Destructor. Their promising use in Australia may lead to adoption in the 

United States, especially if weed control using herbicides declines in effectiveness. Under the No 

Action Alternative, it is likely that the cost of weed management and the time spent managing 

weeds will continue to increase and methods used for weed control will diversify.

Growers choose certain pesticides based on weed, insect and disease pressures, cost of seed and 

other inputs, technology fees, human safety, potential for crop injury, and ease and flexibility of 

the production system (Farnham, 2001; Heiniger, 2000; University of Arkansas, 2008). Growers 

have traditionally used multiple herbicides for weed control. For pre-plant application, herbicides 

that have residual activity are typically used (see Appendix 3). For post- emergent late season 

weed control in corn, synthetic auxins such as 2,4-D and dicamba are often used. For postemergent weed control in soybean, in addition to glyphosate, ALS and PPO inhibitors are often 

used (see Appendices 3 and 4).

Most growers are not expected to increase tillage in the short-term due to the economic (reduced 

fuel use, less time in the field) and environmental benefits (reduced soil erosion and better 

moisture retention) associated with these practices. The fact that tillage is increasing in soybean 

production in the Midwest and Midsouth (Shaw et al., 2012) (and see discussion under tillage in 

Section 4.1.1)., suggests that this increasing tillage trend may continue under the No Action 

Alternative as herbicide-resistant weeds become more difficult to control with available 

herbicide chemistries. In an attempt to offset the increase in tillage that might otherwise result in 

the effort to manage HR weeds, the Natural Resources Conservation Service is offering farmers 

technical and financial assistance to manage HR weeds while maintaining conservation 

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stewardship through two programs: the Conservation Security Program and the Environmental

Quality Incentives Program (Robinson, 2011; 2013). Among the practices that qualify for 

financial and technical incentives are the use of cover cropping and crop rotation (Robinson, 

2013). As a result, cover cropping and crop rotation, both of which have shown promise in

reducing weed pressure (Devore et al., 2013; Murphy et al., 2006; Sosnoskie et al., 2009) may 

increase under the No Action Alternative. Crop rotation may be altered to facilitate the use of 

additional herbicide chemistries, such as glufosinate in the case of Liberty Link® crops, which as 

noted above has increased three fold nationally primarily due to an increased use of glufosinate 

in the Southeast. Crop rotation also may become more diverse to leverage differences in crop 

ecology to shift the dominant weed species and thereby lessen the size of the resistant weed seed 

bank (Murphy et al., 2006; Sosnoskie et al., 2009). Whereas crop rotation is extensively used 

today, cover cropping currently is only used on 1 percent of cropland acreage (Wallander, 2013). 

The fact that cover cropping has been slow to be adopted at present suggests that this practice 

may be even less likely to be adopted under the Action Alternatives where the more familiar 

option, an additional herbicide chemistry through EnlistTM technology, will be available to 

manage glyphosate resistant weeds. Similarly, more diversified crop rotation may be less likely 

to be implemented under the Action Alternatives because the economic returns from growing 

additional crops are likely to be lower than a simple corn soybean rotation. 

Export of Corn and Soybean

Corn is the dominant feed grain traded internationally (USDA-OCE, 2011b). In 2010/11, the 

U.S. produced 38 percent of the total world supply of corn (USDA-OCE, 2011b). Primary 

importers of corn from the U.S. include Japan, Mexico, Korea, Egypt, Taiwan, Syria, the EU and 

China (USDA FAS, 2012b). Approximately 15 to 20 percent of the U.S. corn production is 

exported, with the volume of exports projected to increase over the next decade (DAS, 2010a; 

USDA-OCE, 2011a). Egypt, the EU, Japan, Mexico, Southeast Asia, and South Korea are net 

importers of corn (USDA-FAS, 2011; USDA-OCE, 2011a; b). China is projected to become a 

net importer of corn to support its expanding livestock and industrial sectors (USDA-OCE, 

2011b). The increase in China’s imports is expected to account for one-third of the growth in 

world corn trade (USDA-OCE, 2011b).

Value enhanced, specialty corn is an important part of the U.S. export market for corn. High oil 

corn, for example, is in high export demand as a replacement for animal fats in feed rations 

(USDA-FAS, 2004). The challenges associated with maintaining variety identity in international 

commodity movement increases the costs, as well as the premiums paid, for these specialty crops 

(USDA-FAS, 2004). Trade in feed for livestock has been a driver of this international trade. 

Corn gluten feed is a major product in international trade in feed ingredients (CRA, 2006a). 

Large volumes of U.S. corn gluten feed are exported to the European Union (EU) (CRA, 2006a).

The U.S. is the largest exporter of corn in the world market, exporting 48,500 tons of corn in 

2010, against a global export market of 92,875 tons (USDA-FAS, 2011). How and where the 

corn and corn products will be used will be subject to global market conditions. 

Soybean exports in the form of bulk beans, meal, and oil are a major share of the total 

agricultural exports for the U.S., representing 16.1 percent of the total value of U.S. agricultural 

exports. The value of U.S. agricultural exports was $136 billion in 2011 (USDA-ERS, 2013c). 

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Bulk soybeans accounted for $17.59 billion of this total, ranking first among all agricultural 

commodities, while soybean meal, at a value of $3.2 billion, and soybean oil, at a value of $1.3

billion, ranked 11th and 22nd, respectively (USDA-ERS, 2012c). The U.S. was responsible for 

38 percent of the world’s bulk soybean exports, 13 percent of the world’s soybean meal exports, 

and 11 percent of the world’s soybean oil exports in 2011/12. (USDA-ERS, 2012c).

In 2011/12 soybean meal represented 67 percent of the protein meal produced worldwide, 

although soybean oil ranked behind palm oil in terms of worldwide vegetable oil production

(USDA-ERS, 2012c). Similarly, soybean held the largest share of protein meal consumed 

worldwide mainly as animal feed, with soybean oil again coming in second behind palm oil in 

terms of worldwide vegetable oil consumption (USDA-FAS, 2013b).

In 2011/12, the U.S. was responsible for 35 percent of the world’s soybean production, 21 

percent of world’s soybean meal production, and 21 percent of the world’s soybean oil 

production (USDA-FAS, 2013a). The U.S., China, Argentina, and Brazil are the major producers 

of soybean, soybean meal, and soybean oil (USDA-FAS, 2013a). 

The U.S., along with Brazil, Argentina, Paraguay, and Canada, accounted for 96 percent of the 

bulk soybean exported in 2011/12, while Argentina, Brazil, the U.S., India, and Paraguay 

accounted for 93 percent of the soybean meal exported in 2011/12. Argentina and Brazil are the 

dominant countries in terms of soybean oil exports, accounting for 67 percent of the world total 

in 2011/12. China is the largest importer of U.S. soybeans and soybean products, accounting for 

50 percent of the total value of U.S. soybean and soybean product exports in 2012, followed by 

Mexico (8.9 percent of total) and Japan (4.2 percent) (USDA-FAS, 2013a). China is by far the 

largest importer of soybean, accounting for 64 percent of world imports in 2011/12, followed by 

the EU-27 with 13 percent of world imports. The EU-27 accounted for 36 percent of world 

imports for soybean meal in 2011/12, with Indonesia as the next largest importer (5.7 percent). 

China and India are the largest importers of soybean oil, accounting for 18 percent and 14 

percent of world imports in 2011/12, respectively (USDA-FAS, 2013a).

Over the next decade, global trade in soybeans is expected to increase by 31 percent, soybean 

meal by 17 percent, and soybean oil by 12 percent. The U.S., Brazil, and Argentina are expected 

to continue to account for 88 percent of global exports of soybeans and soybean products. 

Underlying these projections is an assumption that China would continue to be heavily reliant on 

soybean imports, which are projected to rise 59 percent to 90 million tons in 2021/22 (USDAOCE, 2013). 

The increasing cost of weed control due to further development of herbicide-resistant weeds may 

potentially reduce U.S. competitiveness, although these problems are not unique to the U.S. 

Under the No Action Alternative, the U.S. is expected to continue to be a leading producer and 

exporter of corn, soybeans, corn products, and soybean products.

Food and Feed

In the past 30 years, public consumption of corn-based products has more than doubled. Per 

capita consumption of corn products rose from 12.9 pounds annually per capita in 1980 to 33 

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pounds in 2008; and consumption of corn sweeteners increased from 35.3 pounds annually per 

capita to 69.2 pounds during that period (USCB, 2011). During the same time period, the share 

of corn that was GE increased from 0 to 80 percent (USDA-ERS, 2010a). 

Much of the corn consumed by humans has been processed, and processing can reduce residual 

pesticide levels. There are three principal corn product industries in the U.S.: corn refiners, dry 

millers, and distillers. Corn refiners produce starches, sweeteners, ethanol, feed ingredients, corn 

oil, organic acids, amino acids, and polyols (CRA, 2006a). Dry millers manufacture flaking grits, 

snack grits, corn meals, and corn flours and distillers produce beverage and industrial alcohol 

(CRA, 2006a ). The production processes in each of these industries frequently involve several 

sequential mechanical and chemical processes. Depending on the final product, these processes 

include washing, heating, adjusting pH, steeping in an acid solution, fermentation, mechanical 

milling and centrifugal separation, extrusions, pressing and solvent extraction, evaporation and 

filtration, and final refining (Corn Refiners Association, 2006). Each step in the production 

process reduces residual pesticides in the finished product (CRA, 2000). Manufacturing 

operations also have been shown to degrade and denature proteins in corn (Hammond & Jez, 

2011). 

Corn comprises approximately 95 percent of the total feed grain production and use (USDAERS, 2011c). The production of corn for feed use is a derived demand, i.e., production of corn 

for feed will vary depending on the number of animals (cattle, hogs, and poultry) being fed corn 

(USDA-ERS, 2011c). The amount of corn used for feed also depends on the crop’s supply and 

price (USDA-ERS, 2011a). In 2012, beef cattle consumed approximately 30 percent of the total 

corn feed used in the U.S. Poultry accounted for the next highest consumption of corn feed, 

approximately 27 percent, while swine were fed approximately 22 percent, dairy cattle 

approximately 18 percent, and other animals approximately 2 percent (World of Corn, 2013). 

Animal feed derived from corn comes not only from the unprocessed grain, but also from the 

residuals derived from three major corn industries: corn refining, corn dry millers, and distillers 

(CRA, 2006b). Animal feed products from corn refining and wet milling include corn gluten 

feed, corn gluten meal, corn germ meal, corn steep liquor, and amino acids (CRA, 2006a). 

Soybeans yield both solid (meal) and liquid (oil) products. Soybean meal is high in protein and is 

used for products such as tofu, soymilk, meat replacements, and protein powder; it also provides 

a natural source of dietary fiber (USB, 2009). Nearly 98 percent of soybean meal produced in the 

U.S. is used as animal feed, while less than 2 percent is used to produce soybean flour and 

proteins for food use (Soyatech, 2011). Poultry consume more than 45 percent of domestic 

soybean meal or 590 million bushels of the U.S. soybean crop, with soybean oil increasingly 

replacing animal fats and oils in broiler diets (USB, 2011). Soybean can be the dominant 

component of livestock diets, such as in poultry, where upwards of 66 percent of their protein 

intake is derived from soybean(Waldroup & Smith, No Date). Other animals fed domestic 

soybean (by crop volumes consumed) include swine (26 percent), beef cattle (12 percent), dairy

cattle (9 percent), other (e.g., poultry, farm-raised fish 3 percent), and household pets (2 percent) 

(Soy Stats, 2010; USB, 2011). 

Soybean liquids are used to produce salad and cooking oils, baking and frying fat, and 

margarine. Soybean oil is low in saturated fats, high in poly- and monounsaturated fats, and 

83
contains essential omega-3 fatty acids. Soybean oil comprises nearly 70 percent of the oils 

consumed in U.S. households (Soy Stats, 2010).

Although the soybean market is dominated by seed production, soybean has a long history in the 

U.S. as a nutritious grazing forage, hay, and silage crop for livestock (Blount et al., 2009). 

Soybean may be harvested for hay or grazed from the flowering stage to near maturity; the best 

soybean for forage is in the beginning pod stage (Owen et al., 2011a). For silage, it should be 

harvested at maturity before leaf loss and mixed with a carbohydrate source, such as corn, for 

optimal fermentation characteristics (Blount et al., 2009). Varieties of soybean have been 

developed specifically for grazing and hay, but use of the standard grain varieties are 

recommended by some because of the whole plant feeding value (Weiderholt & Albrecht, 2003). 

Non-GE soybean varieties, both those developed for conventional use and for use in organic 

production systems, are not routinely required to be evaluated by any regulatory agency in the 

U.S. for human food or animal feed safety prior to release in the market. Under the Federal Food, 

Drug, and Cosmetic Act (FFDCA), it is the responsibility of food and feed manufacturers to 

ensure that the products they market are safe and properly labeled. Food and feed derived from 

any GE crop events must be in compliance with all applicable legal and regulatory requirements.

Food safety reviews frequently compare the compositional characteristics of the GE crop with 

non-transgenic, conventional varieties of that crop (see also Aumaitre et al., 2002; FAO, 2009). 

Moreover, this comparison also evaluates the composition of the modified crop under actual 

agronomic conditions, including various agronomic inputs (see, e.g., Herman et al., 2010). 

Composition characteristics evaluated in these comparative tests include moisture, protein, fat, 

carbohydrates, ash, minerals, dietary fiber, essential and non-essential amino acids, fatty acids, 

vitamins, and antinutrients (Herman et al., 2010). 

Antinutrients represent an important element of this comparison. Antinutrients are compounds 

produced by a plant that interfere with the absorption and metabolism of the consumed vegetable 

as well as other foods in the digestive tract (Cordain, 1999). Antinutrients in corn include lectins, 

which interfere with vitamin absorption and have been associated with cellular level metabolic 

interference, and trypsin inhibitors, which inhibit protein digestion (Cordain, 1999). 

Antinutrients commonly found in raw soybean also include trypsin inhibitors and lectins (USFDA, 2011c). Routine processing in moist heat inactivates these antinutrients (US-FDA, 2011c).

There are multiple ways in which organisms can be genetically modified through human 

intervention. Traditional methods include breeding or crossing an organism to elicit the 

expression of a desired trait, while more contemporary approaches include the use of 

biotechnology such as genetic engineering to produce new organisms (NRC, 2004). As noted by 

the National Research Council (NRC), unexpected and unintended compositional changes arise 

with all forms of genetic modification, including both conventional hybridizing and genetic 

engineering (NRC, 2004). The NRC also noted in its 2004 report that no adverse human health

effects attributed to genetic engineering have been documented. More recently, the NRC found 

that the cultivation of GE crops has resulted in changes in pesticide application regimens 

(applications of fewer pesticides or using pesticides with lower environmental toxicity), and that 

the cultivation of herbicide-tolerant crops is advantageous because of their superior efficacy in 

84
pest control and concomitant economic, environmental, and presumed personal health 

advantages (NRC, 2010). Reviews on the nutritional quality of GE foods generally have 

concluded that there are no biologically meaningful nutritional differences in conventional 

versus GE plants for food or animal feed (Aumaitre et al., 2002; Faust, 2004; Van Deynze et al., 

2004). 

Human health topics associated with GE crops include the potential toxicity of the introduced 

genes and their products, the expression of new antigenic proteins, and/or altered levels of 

existing allergens (Dona & Arvanitoyannis, 2009; Malarkey, 2003). Under the FFDCA, it is the 

responsibility of food and feed manufacturers to ensure that the products they market are safe 

and labeled properly. Food and feed derived from GE organisms must be in compliance with all 

applicable legal and regulatory requirements. GE organisms for food and feed may undergo a 

voluntary consultation process with the FDA prior to release onto the market. The PAT protein,

conferring resistance to glufosinate, has already been evaluated by FDA; soybean (and other 

crops) containing the pat gene are already in commerce. The CP4 EPSPS protein derived from 

Agrobacterium spp. confers resistance to glyphosate and has already been evaluated by FDA; 

GR crops have been present in commerce since 1996. Consumer consumption of GE soybean is 

expected to continue to follow current levels in the future.

GE organisms for food and feed typically undergo a voluntary consultation process with the 

FDA prior to release onto the market. Although a voluntary process, thus far, all applicants who 

have wished to commercialize a GE variety that would be included in the food supply have 

completed a consultation with the FDA. In such consultation, a developer who intends to 

commercialize a bioengineered food meets with FDA to identify and discuss relevant safety, 

nutritional, or other regulatory issues regarding the bioengineered food and then submits to FDA 

a summary of its scientific and regulatory assessment of the food. This process includes: 1) an 

evaluation of the amino acid sequence introduced into the food crop to confirm whether the 

protein is related to known toxins and allergens; 2) an assessment of the protein’s potential for 

digestion; and 3) an evaluation of the history of safe use in food (Hammond & Jez, 2011). FDA 

evaluates the submission and responds to the developer by letter with any concerns it may have

or additional information it may require.

Dow has provided the FDA with information on the identity, function, and characterization of 

the genes for DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean. Dow has 

completed consultations with FDA for DAS-40278-9 corn (BNF-120) (US-FDA, 2011c); DAS68416-4 soybean (BNF-124) (US-FDA, 2011a); and DAS-44406-6 soybean (BNF-133) (USFDA, 2013a). 

Currently over 90 percent of the corn and soybean grown in the U.S. is GE (USDA-NASS, 2006)

and this market share is expected to continue under the No Action Alternative. Americans are 

routinely exposed to the PAT protein and CP4 EPSPS protein found in LibertyLink® and 

Roundup Ready® biotech crops currently and this exposure is expected to continue under the No 

Action Alternative. Both of these proteins are considered to be safe for consumption by humans 

and animals. 

Worker Safety

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Agriculture is one of the most hazardous industries for U.S. workers. As a result, in 1990, 

Congress directed the National Institute of Occupational Safety and Health to develop a program 

to address high-risk issues related to occupational workers. In consideration of the risk of 

pesticide exposure to field workers, EPA’s Worker Protection Standard (WPS) (40 CFR Part 

170) was published in 1992 to require actions to reduce the risk of pesticide poisonings and 

injuries among agricultural workers and pesticide handlers. The WPS offers protections to more 

than two and a half million agricultural workers who work with pesticides at more than 560,000 

workplaces on farms, forests, nurseries, and greenhouses. The WPS contains requirements for 

pesticide safety training, notification of pesticide applications, use of personal protective 

equipment, restricted entry intervals following pesticide application, decontamination supplies, 

and emergency medical assistance. On February 20, 2014, the US-EPA announced proposed 

changes to the agricultural WPS to increase protections from pesticide exposure for agricultural 

workers and their families.6 EPA is proposing to strengthen the protections provided to 

agricultural workers and handlers under the WPS by improving elements of the existing 

regulation, such as training, notification, communication materials, use of personal protective 

equipment, and decontamination supplies. The proposed changes to the current WPS 

requirements, specifically improved training on reducing pesticide residues brought from the 

treated area to the home on workers and handlers' clothing and bodies and establishing a 

minimum age for handlers and early entry workers, other than those covered by the immediate 

family exemption, mitigate the potential for children to be exposed to pesticides directly and 

indirectly. EPA expects the revisions, once final, to prevent unreasonable adverse effects from 

exposure to pesticides among agricultural workers and pesticide handlers; vulnerable groups, 

such as minority and low-income populations, child farmworkers, and farmworker families; and 

the general public. Furthermore, the Occupational Safety and Health Administration requires all 

employers to protect their employees from hazards associated with pesticides and herbicides. 

Pesticides, including herbicides, are used on most corn and soybean acreage in the U.S. Changes 

in acreage, crops, or farming practices can affect the amounts and types of pesticides used and 

thus the risks to workers. The EPA pesticide registration process, however, involves the design 

of use restrictions that if followed have been determined to be protective of worker health. 

Growers are required to use pesticides consistent with the application instructions provided on 

the EPA-approved pesticide labels. Worker safety precautions and use restrictions are clearly 

noted on pesticide registration labels. These restrictions provide instructions as to the appropriate 

levels of personal protection required for agricultural workers to use herbicides. These may 

include instructions on personal protective equipment, specific handling requirements, and field 

reentry procedures. Used in accordance with the EPA label, these herbicides have been 

determined to not present a health risk to workers (US-EPA, 2005b; 2008).

6 For the proposed changes see: http://www.epa.gov/oppfead1/safety/workers/proposed/index.html

86

 
Under FIFRA, all pesticides (which is inclusive of herbicides) sold or distributed in the U.S. 

must be registered by the EPA (US-EPA, 2005a). Registration decisions are based on scientific 

studies that assess the chemical’s potential toxicity and environmental impact. To be registered, a 

pesticide must be able to be used without posing unreasonable risks to people or the 

environment. All pesticides registered prior to November 1, 1984, such as 2,4-D, must also be 

reregistered to ensure that they meet the current, more stringent standards. The reregistration 

decision for 2,4-D was issued in 2005 (US-EPA, 2005b). 

The current labels for both 2,4-D and quizalofop include label use restrictions intended to protect 

humans, including protective equipment to be worn during mixing, loading, applications and 

handling, equipment specifications to control pesticide application, and reentry periods 

establishing a safe duration between pesticide application and exposure to the pesticide in the 

field (DuPont, 2010; Nufarm, 2009). Used in accordance with the label, these herbicides have 

been determined to not present a health risk to humans (US-EPA; 2007). 

Agronomic practices used for corn production, such as the application of agricultural chemicals 

(pesticides and fertilizers) may become more diverse as growers incorporate more sites of action 

to manage GR weeds. Growers choose certain pesticides based on weed, insect and disease 

pressures, cost of seed and other inputs, technology fees, human safety, potential for crop injury, 

and ease and flexibility of the production system (Farnham, 2001; Heiniger, 2000; University of 

Arkansas, 2008). Agricultural production of existing nonregulated herbicide-resistant GE and 

non-GE corn and soybean use EPA-registered pesticides, including glyphosate and 2,4-D for 

weed management. 2,4-D use is currently authorized by EPA for application to corn and preplant application to soybean. Quizalofop is currently authorized by EPA for application to 

soybean. Glufosinate is authorized for application to both LibertyLink® corn and soybean and its 

use in increasing on soybean (Appendix 4). It is expected that under the No Action Alternative, 

more herbicide chemistries will be needed to control glyphosate resistant weeds than under the 

Action Alternatives and as a consequence, workers are likely to be exposed to a wider range of 

chemistries. It is also expected that more frequent herbicide applications and tillage will be 

needed ((Culpepper, 2008; Heap, 2011b; Owen & Zelaya, 2005; Owen, 2008) thereby increasing 

the use of farm equipment under the No Action Alternative relative to the Action Alternatives. 

4.1.2 Biological Resources

Animal Communities

Invertebrates

Invertebrate communities in cornfields represent a diverse assemblage of feeding strategies 

including predators, crop-feeders, saprophages, parasites, and polyphages (Stevenson et al., 

2002). Numerous insects and related arthropods perform valuable functions; they pollinate 

plants, contribute to the decay and processing of organic matter, reduce weed seed 

populations through predation, cycle soil nutrients, and attack other insects and mites that 

are considered to be pests. Although many arthropods in agricultural settings are considered 

pests, such as the European corn borer (Ostrinia nubilalis) and the corn rootworm 

(Diabrotica spp.) (Willson & Eisley, 2001), there are many beneficial arthropods which are 

natural enemies of both weeds and insect pests (Landis et al., 2005). Some of these 

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beneficial species include the convergent lady beetle (Hippodamia convergens), carabid 

beetles, the caterpillar parasitoids (e.g., Meteorus communis and Glyptapanteles militaris),

and the predatory mite (Phytoseiulus persimilis) (Shelton, 2011). Earthworms, termites, ants, 

beetles, and millipedes contribute to the decay of organic matter and the cycling of soil 

nutrients (Ruiz et al., 2008). Some high-profile or representative invertebrate species, such as 

honey bees, earthworms, and butterflies, are generally studied more thoroughly than others. 

Insects and other invertebrates can be beneficial to soybean production, providing services such 

as nutrient cycling and preying on plant pests. Insects are considered less problematic than weeds 

in U.S. soybean production; nevertheless, insect injury can impact yield, plant maturity, and seed 

quality. Insect pests are managed during the growth and development of soybean to enhance 

soybean yield (Aref & Pike, 1998; Higley & Boethel, 1994). Insect injury in soybean seldom 

reaches levels that cause significant economic loss, as indicated by the low percentage (16 

percent) of soybean acreage that receive insecticide treatments (USDA-NASS, 2009e). Some of 

the many insects and invertebrates that are detrimental to soybean crops include: bean leaf beetle 

(Cerotoma trifurcata), beet armyworm (Spodoptera exigua), blister beetle (Epicauta spp.), corn 

earworm (Helicoverpa zea), grasshopper (Acrididae spp.), green cloverworm (Hypena scabra), 

seed corn beetle (Stenolophus lecontei),; seedcorn maggot (Delia platura), soybean aphid (Aphis 

glycines), soybean looper (Pseudoplusia includens), soybean stem borer (Dectes texanus), spider 

mites (Tetranychus urticae), stink bug (green [Acrosternum hilare]; brown [Euschistus spp.]),; 

and velvetbean caterpillar (Anticarsia gemmatalis) (Palmer et al., No Date; Whitworth et al., 

2011).

Modern agricultural practices have been noted to simplify the agricultural landscape, with 

the result that beneficial arthropods may be adversely affected (Landis et al., 2005). 

Intensively cultivated lands, such as those used in corn and soybean production, provide less 

suitable habitat for wildlife use than that found in fallow fields or adjacent natural areas. As such, 

the types and numbers of animal species found in corn and soybean fields are less diverse by 

comparison. 

Birds

Corn and soybean fields have been shown to provide both food and cover for wildlife, including 

a variety of birds as well as large and small mammals (Palmer et al., 2011; Vercauteren & 

Hygnostrom, 1993). 

The types and numbers of birds that inhabit cornfields vary regionally and seasonally, but for the 

most part the numbers are low (Patterson & Best, 1996). Most of the birds that use cornfields are 

ground foraging omnivores that feed on corn seed, sprouting corn, and the corn remaining in the 

fields following harvest. Bird species commonly observed foraging on corn include red-winged 

blackbird (Agelaius phoeniceus), horned lark (Eremophila alpestris), brown-headed cowbird 

(Molothrus ater), vesper sparrow (Pooecetes gramineus), ring-necked pheasant (Phasianus 

colchicus), wild turkey (Meleagris gallopavo), American crow (Corvus brachyrhynchos), and

various grouse and quail species (Dolbeer, 1990; Mullen, 2011; Patterson & Best, 1996). 

Following harvest, it is also common to find large flocks of Canada goose (Branta canadensis), 

Snow goose (Chen caerulescens), Sandhill cranes (Grus canadensis), and other migratory 

88
waterfowl foraging in cornfields (Sherfy et al., 2011; Sparling & Krapu, 1994; Taft & Elphick, 

2007).

Migratory birds feed on spilled soybean following crop harvest (Galle et al., 2009) although 

more birds feed on nearby corn and sunflower seed fields. As many as 28 desirable (non-crop 

pest) bird species, as well as another five that can be crop pests in sunflower, have been 

identified as resident in soybean and corn fields in the Dakotas (Gamble et al., 2002). 

Mammals

A variety of mammals forage on corn at various stages of production. For the most part, 

herbivorous and omnivorous mammals feed on the ear at various stages of growth. Large- to 

medium-sized mammals that are common foragers of cornfields include: white-tailed deer 

(Odocoileus virginianus), raccoon (Procyon lotor), feral pigs (Sus scrofa), and woodchuck 

(Marmota monax). The most notable of these is the white-tailed deer which often inhabit 

woodlots adjacent to cornfields and frequent these fields for both food and cover, especially in 

mid-summer (Vercauteren & Hygnostrom, 1993). The effects of deer herbivory on cornfields 

have been well-documented. Cornfields are vulnerable to deer damage from emergence through 

harvest (Vercauteren & Hygnostrom, 1993), but any damage at the tasseling stage most directly 

impacts yield (Stewart et al., 2007). White-tailed deer are considered responsible for more corn 

damage than any other wildlife species (Stewart et al., 2007). 

In addition to deer, significant damage to corn by raccoons also has been documented (Beasley 

& Rhodes, 2008; DeVault et al., 2007). Corn has been shown to constitute up to 65 percent of the 

diet of raccoons during the late summer and fall (MacGowan et al., 2006). 

As with these larger mammals, small mammal use of cornfields for shelter and forage also varies 

regionally and includes (Nielsen, 2005):

• Deer mouse (Peromyscus maniculatus),

• Meadow vole (Microtus pennsylvanicus),

• House mouse (Mus musculus), and

• Thirteen-lined ground squirrel (Spermophilus tridecemlineatus).

Throughout the U.S., the deer mouse is the most common small mammal in almost any 

agricultural field (Stallman & Best, 1996; Sterner et al., 2003). Deer mice feed on a wide variety 

of plant and animal matter depending on availability, but primarily feed on seeds and insects. 

Deer mice have been considered beneficial in agroecosystems because they consume both weed 

and insect pests (Smith, 2005).

The meadow vole feeds primarily on fresh grass, sedges, and herbs, and also on seeds and grains

of field crops. Although the meadow vole may be considered beneficial for its role in the 

consumption of weeds, this vole can be a significant agricultural pest where abundant when it 

consumes seeds in the field. Meadow vole populations are kept in check by high intensity 

agriculture methods, including conventional tillage; this vole is often associated with the field 

edges where cover is found off the field, as well as limited tillage agriculture and strip crops

(Smith, 2005).

89
The lined ground squirrel feeds primarily on seeds of weeds and available crops, such as corn 

and wheat. This species has the potential to damage agricultural crops, although it also can be 

considered beneficial when eating pest insects, such as grasshoppers and cutworms (Smith, 

2005).

Rodents, such as mice or squirrels, may seasonally feed exclusively on soybean seeds. During 

the winter months, leftover and unharvested soybeans provide a food source for wildlife. Whitetailed deer and groundhogs feed on soybean and cause soybean damage, while eastern cottontail, 

raccoon, Canada goose, squirrels, and other rodents (such as ground squirrel) also feed on 

soybean, but their damage is of less importance (MacGowan et al., 2006). Deer in large numbers 

may significantly damage soybean in site-specific circumstances by browsing in soybean fields 

for forage, and in some areas, growers may be issued licenses to kill deer outside the regular 

hunting season to reduce crop damage (Berk A, 2008; Garrison & Lewis, 1987). Deer may also 

feed on seed left after harvest. In Georgia, feral hogs have also damaged soybean fields through 

rutting and feeding (GDNR, 2003). It is likely that reptiles and amphibians may also be found in 

soybean fields, especially if the habitat surrounding the field is suitable to support these types of 

animals. 

The widespread use of conservation tillage and no-till practices associated with the use of 

herbicides for weed control especially in association with the planting GE HR corn and soybean 

varieties (Dill et al., 2008; Givens et al., 2009) has benefitted wildlife through improved water 

quality, availability of waste grain, retention of cover in fields, and increased populations of 

invertebrates (Brady, 2007; Sharpe, 2010). Conservation tillage practices that leave greater 

amounts of crop residue serve to increase the diversity and density of birds and mammals 

(USDA-NRCS, 1999a). Increased residue also provides habitat for insects and other arthropods, 

consequently increasing this food source for insect predators. Insects are important during the 

spring and summer brood rearing season for many upland game birds and other birds because 

they provide a protein-rich diet to fast-growing young, as well as a nutrient-rich diet for 

migratory birds (USDA-NRCS, 2003).

Corn and soybean production practices can affect terrestrial and aquatic species directly or 

indirectly. Practices such as tillage, cultivation, pesticide and fertilizer applications, and the use 

of agricultural equipment can result in run-off, increased soil turbidity, decreased soluble oxygen 

or habitat destruction. The continued emergence of GR weeds will likely require modifications 

of crop management practices to address these weeds. Herbicide use may increase to meet the 

need for additional integrated weed management tactics to mitigate herbicide-resistant weeds in 

different cropping systems (Culpepper, 2008; Heap, 2011c; Owen & Zelaya, 2005; Owen, 2008). 

Some of these adjustments may impact the adoption of conservation tillage practices. Under the 

No Action Alternative, if tillage rates continue to increase as a means of weed suppression, 

increased soil erosion and indirect adverse impacts on wildlife are expected. Likewise if 

increased amounts of pesticide are used, adverse impacts on wildlife are also expected. If cover 

cropping becomes more commonplace, it is expected to have beneficial impacts on wildlife by 

providing habitat and food. As these management practices may have both beneficial and 

adverse effects on biological resources, their impacts on biological resources under the No 

Action Alternative are unknown. 

90
Growers choose pesticides based on weed, insect and disease pressures, cost of seed and other 

inputs, technology fees, human safety, potential for crop injury, and ease and flexibility of the 

production system (Farnham, 2001; Heiniger, 2000; University of Arkansas, 2008). Agricultural 

production of corn and soybean uses EPA-registered pesticides, including glyphosate and 2,4-D,

for weed management. The environmental risks of pesticide use on wildlife and wildlife habitat

are assessed by EPA in the pesticide registration process and are regularly reevaluated by EPA 

for each pesticide to maintain its registered status under FIFRA.

Terrestrial and aquatic species in the agroecosystem have been exposed to the CP4 EPSPS 

protein in glyphosate-tolerant soybeans (and corn) for more than 15 years, without any indication 

of adverse effects on the animals from that protein, including any allergic effects or toxicity

(Economidas et al., 2010; Snell et al., 2012). The plants expressing that protein do not vary 

substantially in nutritional composition or physical structure from plants lacking protein. The 

enzyme protein is not biologically active in soil or water, and it is rapidly and fully 

biodegradable in the environment. 

Animal species have also been exposed to the PAT protein in glufosinate-tolerant soybeans (and 

corn) for many years, likewise without ill-effects from that protein (Economidas et al., 2010; 

Snell et al., 2012). The safety of food and feed containing the PAT protein was reviewed as part 

of previous assessments and was shown to present no significant food or feed safety risk. A 

biotechnology consultation on the PAT protein was conducted in 1998 and does not require 

additional evaluation by FDA (US-FDA, 1998).

Plant Communities

Weeds are commonly found in corn and soybean fields and, if not controlled, can significantly 

decrease yields. The most problematic weeds of each crop and the acres that were actively 

managed in 2006-2008 are shown in Appendix 5. Appendix 3 lists three categories of weeds: 

annual broadleaf weeds, annual grass weeds, and perennial weeds. Among these three categories, 

annual broadleaf weeds include the species that have become most difficult to control due to the 

selection of HR biotypes. For example, velvetleaf and lambsquarters are both somewhat tolerant 

of glyphosate and for some species such as pigweed, waterhemp, ragweed, and kochia, GR

biotypes have been selected (Heap, 2013b). Species such as waterhemp have developed 

resistance to as many as five different herbicide sites of action (Owen, 2012). Biotypes resistant 

to 2,4-D have been selected in morning glory(Heap, 2013b), which is one of the other problem 

weeds of corn and soybean(Appendix 5). Annual grass weeds that inhabit corn and soybean 

fields are still largely controlled by glyphosate. Foxtail is the most prevalent grass weed and is 

actively managed on almost all acreage used for corn production and much of the land used for 

soybean. Perennial weeds are particularly difficult to control because they can regrow every year 

from rhizomes. (DAS, 2010a). Among the perennial weeds, biotypes of Johnson grass have been 

selected for glyphosate resistance. 

The majority of weeds that are problems in corn are also problems in soybean (see Chapter 5 

Cumulative Effects for more details). In addition, corn volunteers are controlled on 2 to 4 million 

acres of soybean whereas soybean volunteers are generally not managed in corn production 

fields. 

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Corn

Corn generally does not survive until the following spring in those regions where freezing 

temperatures are reached in the winter; however, corn seeds which are incorporated in the soil 

during either harvest or fall tillage may overwinter and grow the following spring (Stewart, 

2011). Volunteer corn lacks vigor and competitiveness because the volunteer plant is two 

generations removed from the cross which produced the original seed, resulting in a loss of 

hybrid vigor (Davis, 2009). One cause of volunteer corn is when weather late in the growing 

season causes ears to drop or lodging occurs, placing ears of corn on the ground where the seed 

can then germinate the following year. Volunteer corn can be present as single plants or as 

clumps formed when an ear drops to the ground and is partially buried (Davis, 2009; Wilson et 

al., 2010). 

Volunteer corn is less of a concern in no-till fields than in fall-tilled fields because of the lower 

probability that corn seed will survive and germinate in the following growing season (Bernards 

et al., 2010). In no-till fields, the fallen corn is frequently eaten by wildlife and also is subject to 

winter weather conditions (Bernards et al., 2010). In fall tillage systems, corn seed may be buried 

in the soil and overwinter. Volunteer corn which has emerged from this overwintered seed 

requires control with spring tillage or with application of herbicides (Bernards et al., 2010).

Literature clearly notes that genetically engineered corn is a problematic volunteer the year after 

harvest in soybean, dry beans, sugar beets, and subsequent corn crops (Bernards et al., 2010; 

Davis, 2009; Hager, 2009; Johnson et al., 2010; Stewart, 2011; Wilson et al., 2011a; Wilson et 

al., 2010). For example, the presence of volunteer corn in soybeans was identified in 12 percent

of the soybean acreage in Illinois in a 2005 survey of soybean acreage in corn–soybean rotation 

systems (Davis, 2009). Additionally, a 2010 survey of soybean cultivation in Illinois identified a 

field with up to 500,000 corn plants per acre (Hager, 2010). The effect of volunteer corn on the 

yields of the intended crop depends on the density of the volunteers (Bernards et al., 2010; 

Davis, 2009). In controlled agronomic studies, an analysis of yield impacts to soybeans from 

volunteer corn was evaluated at densities up to 17,800 corn plants per acre of soybean (Alms et 

al., 2007; 2008). In these controlled studies, volunteer corn densities ranging from zero plants per 

square meter up to 4.4 plants per square meter were cultivated in soybean, with corresponding 

soybean yield losses of up to 58 percent (Alms et al., 2007; 2008). Pre-harvest herbicide 

treatments of the volunteer corn reduced but did not eliminate the yield impacts. 

Volunteer glyphosate and glufosinate resistant corn in cornfields can be controlled using interrow cultivation and several different herbicides (Minnesota, 2009; Sandell et al., 2009). Preemergent controls might include Gramoxone Inteon (paraquat) mixed with Atrazine (Monsanto, 

2010b; Sandell et al., 2009). If the volunteer corn is stacked to express both glyphosate and 

glufosinate resistance, inter-row cultivation is the only option for post-emergent control within 

corn (Sandell et al., 2009). Post-emergent grass herbicide ACCase inhibitors, such as quizalofop, 

fluazifop, fenoxaprop, sethoxydim, and clethodim (Bernards et al., 2010; Hager, 2009; Johnson 

et al., 2010) are effective to control volunteer corn in soybean and other broadleaf crops. ALS 

inhibitors, such as the sulfonylureas, imidazolinone, and triazolopyrimidine also have been

identified for potential control of glyphosate- or glufosinate-resistant corn (see, Hager, 2009; 

Wisconsin, 2011). Herbicide tank mix additives are recommended to increase on-plant spray 

92
retention and absorption (see Hager & McGlamery, 1997; Johnson et al., 2010; Sandell et al., 

2009). Recommended additives include crop oil concentrate methylated seed oil and ammonium 

sulfate (Hager & McGlamery, 1997; Johnson et al., 2010; Monsanto, 2010b). Imazethapyr has 

been identified to control up to 80 percent of the volunteer corn when the corn is still in early 

growth stages (Bernards et al., 2010). The ACCase-inhibiting herbicides are to be applied prior 

to the corn reaching the 12- to 24-inch tall stage and the ALS herbicides are effective in 

controlling smaller (2- to 8-inch) corn (Minnesota, 2009; Monsanto, 2010b). 

For volunteer corn in soybean, growers can take advantage of alternate modes of herbicide action 

if the herbicide resistance differs between the current crop and the volunteer (e.g., glufosinate in 

LibertyLink® soybean to control a Roundup Ready® GR volunteer corn variety) (Minnesota, 

2009). In experimental studies, volunteer corn in soybean were controlled using different 

application rates of the herbicide Clethodim in the attempt to better quantify soybean yield loss 

(Alms et al., 2008). Clethodim treatments of the volunteer corn did reduce the volunteer corn 

density, although even after a 98 percent control of the volunteer corn, soybean yield still 

suffered a 5 percent reduction in yield (Alms et al., 2008). Under the No Action Alternative, the 

above listed methods for controlling volunteer corn are expected to continue. These methods of 

volunteer control are also expected under the Action Alternatives with the exception that 

quizalofop will no longer be useful for controlling corn volunteers in soybean.

Soybean

Modern soybean harvesting equipment is so efficient that few seeds remain in soybean fields 

following harvest and few volunteer soybeans are typically seen in subsequent crops with which 

the beans are rotated. Additionally, volunteer soybeans do not easily compete with other crops 

and are easily controlled with common agronomic practices. Volunteer soybeans are limited by 

the geography in which soybean is planted. Soybean requires specific environmental conditions 

to grow as a volunteer (OECD, 2000). Mature soybean seeds are sensitive to cold and rarely

survive in freezing winter conditions (Raper & Kramer, 1987). Volunteer soybeans can occur in 

regions with warmer climates where temperature and moisture conditions are suitable for 

viability and germination can occur year-round, such as the Mississippi Delta and the southeast

U.S. (Zapiola et al., 2008). York (York et al., 2005) reports that soybean volunteers were found 

in no-till cotton fields especially where the previous soybean crop harvest was prevented by 

hurricane and consequently many seeds remained in the field. According to this report, soybean 

volunteers are becoming more common as Roundup-Ready technology has led to an increase in 

the adoption of no-till and a decrease in the number of herbicides used in rotation crops (York et 

al., 2005). For similar reasons, soybean volunteers are also now appearing in corn, too 

(Gunsolus, 2010). York (York et al., 2005) reported effective control of soybean volunteers in 

cotton with normal levels of the ALS herbicide, trifloxysulfuron, an herbicide that also controls 

Enlist® soybean. In corn, volunteer soybean can be effectively controlled by atrazine, dicamba, 

and clopyralid (Gunsolus, 2010). Use of these herbicides in corn would not be a departure from 

current agronomic practice as all three are among the ten most commonly used herbicides on 

corn (FEIS Table 4-1). Under the No Action Alternative, the above listed methods for controlling 

volunteer soybean are expected to continue. These methods of volunteer control are also 

expected under the Action Alternatives.

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4.1.3 Natural Resources

Soil Quality

Corn is cultivated in a wide variety of soils across the U.S. (see, e.g., Corn Crop Profiles 

provided at www.ipmcenters.org). Soybean production is best suited to fertile, well-drained,

medium-textured loam soils, yet they can be produced in a wide range of soil types (Berglund & 

Helms, 2003; NSRL, No Date). Similarly, soils that are high in clay and low in humus may 

impede soybean plant emergence and development (NSRL, No Date). Soils with some clay 

content may increase moisture availability during periods of low precipitation (Cox et al., 2003).

Land management practices for crop cultivation can affect soil quality. While practices such as 

tillage, fertilization, the use of pesticides and other management tools can improve soil health, 

they can also cause substantial damage if not properly used. Several concerns relating to soil and 

agricultural practices include increased erosion, soil compaction, degradation of soil structure, 

nutrient loss, increased salinity, change in pH, and reduced biological activity (USDA-NRCS, 

2001a). 

With conventional tillage, a grower prepares the seedbed by removing all plant residues and 

weeds from the soil surface prior to planting, and then continues to cultivate the soil while the 

crop is growing to control late emerging weeds (NCGA, 2007b). This practice can result in soil 

loss to wind and water erosion (NCGA, 2007b). Conservation practices, including conservation 

tillage, have been developed to reduce field tillage and thus reduce the corresponding soil loss 

(USDA-NRCS, 2006c). Conservation tillage employs tools that disturb soil less and leave at 

least 30 percent of crop residues on the surface (Peet, 2001), whereas no-till farming only 

disturbs the soil for planting seed. The new crop is planted into the plant residue or in narrow 

strips of tilled soil (Peet, 2001). 

Reducing excessive tillage through practices such as conservation tillage minimizes the loss of 

organic matter and protects the soil surface by leaving plant residue on the surface. Soil organic 

matter is probably the most vital component in maintaining quality soil; it is instrumental in 

maintaining soil stability and structure, reducing the potential for erosion, providing energy for 

microorganisms, improving infiltration and water holding capacity. It is also important in 

nutrient cycling, cation exchange capacity,7 and the breakdown of pesticides (USDA-NRCS, 

1996). Other attributes of conservation tillage include the retention of beneficial insects, 

increased soil water-holding capacity, less soil and nutrient loss from the field, reduced soil 

7 Cation exchange capacity is the ability of soil anions (negatively charged clay; organic matter; and inorganic 

minerals, such as phosphate, sulfate, and nitrate) to adsorb and store soil cation nutrients (positively charged ions, 

such as potassium, calcium, and ammonium).

94

 
compaction, and less time and labor required to prepare the field for planting (Peet, 2001) (Leep 

et al., 2003; NCGA, 2007b; c; USDA-NRCS, 2006b; c). 

Total soil loss on highly erodible croplands and non-highly erodible croplands decreased from 

462 million tons per year to 281 million tons per year or by 39.2 percent from 1982 to 2003 

(USDA-NRCS, 2006a). This decrease in soil erosion carries a corresponding decrease in nonpoint source surface water pollution of fertilizer and pesticides (NCGA, 2007b). The reduction in 

soil erosion also is attributed to a decrease in the number of acres of highly erodible cropland 

being cultivated (USDA-NRCS, 2006b).

All regions showed a decrease in amount of water or wind erosion between 1982 and 2007

(USDA-NRCS, 2010a). The Corn Belt and the Northern Plains were the areas where most water 

erosion occurred. This is where the majority of the corn and soybean are produced in the U.S.

While conservation tillage does have several benefits for soil health, some management concerns 

are associated with its use. Under no-till practices, soil compaction may become a problem 

because tillage is useful for breaking up compacted areas (USDA-NRCS, 1996). Likewise, not 

all soils (such as wet and heavy clay soils in northern latitudes) are suited for no-till practices. 

Also, no-till practices may lead to increased pest occurrences that conventional tillage is better 

suited to managing (NRC, 2010).

Growers producing crops on highly erodible land are encouraged to maintain a soil conservation 

plan approved by the USDA National Resources Conservation Service (USDA-ERS, 2010b).

These soil conservation plans are prepared by the grower pursuant to the 1985 Food Security Act 

Conservation Compliance and Sodbuster programs to minimize soil erosion (USDA-ERS, 

2010b).

Other methods to improve soil quality include careful management of fertilizers and pesticides; 

use of cover crops to increase plant diversity and limit the time soil is exposed to wind and rain; 

and, increased landscape diversity with buffer strips, contour strips, wind breaks, crop rotations, 

and varying tillage practices (USDA-NRCS, 2006b). Weed scientists indicate that an integrated 

weed management plan defined by a range of weed management strategies must be considered, 

including mechanical strategies, alternative herbicides, and cultural approaches (University of 

Georgia, 2009). Nonetheless, if herbicide-resistant weeds become problematic enough where 

other strategies are not effective, growers will likely have to consider mechanical control 

strategies which may, in turn, potentially impact soil quality. Residue management that employs 

intensive tillage and leaves low amounts of crop residue on the surface results in greater losses of 

soil organic matter (USDA-NRCS, 1996). The total acreage that may be impacted by such an 

increase in tillage would be based on the extent of resistant weeds present in a field and the weed 

management strategy chosen by a grower. However, it is important to note that much of the 

reduction in soil erosion occurred prior to the adoption of GE HR crops and even an increase in 

some tillage is not expected to return erosion level to those seen in the 1980’s.

Under the No Action Alternative GR weeds are expected to continue to be a concern in the 

Southeast region, and the likely expansion of resistance into the Great Plains, Northern Crescent, 

and Heartland regions (Stachler & Christoffers, 2012) would require modifications of crop 

95
management practices to address these weeds, which can affect soils. These changes may include 

diversifying the mode of action of herbicides applied to corn and soybean and making 

adjustments to crop rotation and tillage practices (Owen et al., 2011a). 

Prostko and Wright (Prostko, 2013; Wright, 2013) described changes in management practices in 

Georgia and Florida as follows: “growers in Georgia, who currently are experiencing herbicideresistant Palmer amaranth infestations, significantly changed the way they farm. The use of 

residual herbicides, tillage (moldboard plowing), cover crops, and/or hand-weeding have become 

the norm for almost all growers.” “Most of the little soybean produced in Florida is grown using 

conservation tillage of various types, although the occurrence of GR palmer amaranth has made 

this increasingly difficult. There is a move to using small amounts of carefully targeted 

cultivation at intervals to remove problem weeds.” (Prostko, 2013; Wright, 2013).

Herbicide use may increase to control herbicide-resistant weeds in different cropping systems 

(Culpepper, 2008; Heap, 2011c; Owen & Zelaya, 2005; Owen, 2008). Pesticide use has the 

potential to affect soil quality due to the impact to the soil microbial community. 

The adoption of no-till farming is not uniform across soybean and corn growing areas. Table 7

shows the states where no-till is adopted on a higher percent of the acres than conventional 

tillage. For the majority of these survey states, the transition to more no-till than conventional 

tilled acres occurred after 2005 (USDA-ERS, 2012d).

Soil Microorganisms

The inorganic and organic matter in soil is home to a wide variety of fungi, bacteria, and 

arthropods, and represents the growth medium for terrestrial plant life (USDA-NRCS, 2004).

Soil microorganisms play a key role in soil structure formation, decomposition of organic matter, 

toxin removal, nutrient cycling, and most biochemical soil processes (Garbeva et al., 2004; 

Jasinski et al., 2003; Young & Ritz, 2000). They also suppress soil-borne plant diseases and 

promote plant growth (Doran et al., 1996). 

The main factors affecting microbial population size and diversity include plant type (providers 

of specific carbon and energy sources into the soil), soil type (texture, structure, organic matter, 

aggregate stability, pH, and nutrient content), and agricultural management practices (crop 

rotation, tillage, herbicide and fertilizer application, and irrigation) (Garbeva et al., 2004; Young 

& Ritz, 2000). Some types of soil micro-organisms share metabolic pathways with plants and 

might be affected by herbicides. Tillage disrupts multicellular relationships among microorganisms, and crop rotation changes soil conditions in ways that favor different microbial 

communities.

Microbial diseases affecting corn include those caused by the fungal pathogens northern leaf spot 

(Helminthosporium carbonum); northern corn leaf blight, (Exserohilum turcicum); southern corn 

rust, (Puccinia polysora); common corn rust, (Puccinia sorghi); anthracnose leaf blight, 

(Colletotrichum graminicola); and gray leaf spot, (Cercospora zeae-maydis) (Ruhl, 2007). 

Management to control disease outbreaks varies by region and pathogen, but include common 

practices such as crop rotation, weed control, planting resistant cultivars, and proper planting and 

tillage practices.

96
Plant roots, including those of soybean, release a variety of compounds into the soil creating a 

unique environment for microorganisms in the rhizosphere (root zone). Microbial diversity in the 

rhizosphere may be extensive and differs from the microbial community in the bulk soil

(Garbeva et al., 2004). 

An important group of soil microorganisms associated with legumes, including soybean, are the 

mutualists. These include mycorrhizal fungi, nitrogen-fixing bacteria, and some free-living 

microbes that have co-evolved with plants that supply nutrients to and obtain food from their 

plant hosts (USDA-NRCS, 2004). Legumes have developed symbiotic relationships with specific 

nitrogen-fixing bacteria in the family Rhizobiaceae that induce the formation of root nodules 

where bacteria may carry out the reduction of atmospheric nitrogen into ammonia (NH3) that is 

usable by the plant (Gage, 2004). Bradyrhizobium japonicum is the rhizobium bacteria 

specifically associated with soybeans (Franzen, 1999). Since neither soybean nor B. japonicum is 

native to North America, if a field has not been planted with soybean within three to five years, 

either the seed or seed zone must be inoculated with B. japonicum prior to soybean planting 

(Abendroth & Elmore, 2006). 

In addition to beneficial microorganisms, there are also several microbial pathogens that cause 

disease in soybean, which vary somewhat depending on the region. These include fungal 

pathogens such as Rhizoctonia stem rot (Rhizoctonia solani), brown stem rot (Phialophora

gregata), sudden death syndrome (Fusarium solani race A), and charcoal root rot

(Macrophomina phaseolina); bacterial pathogens bacterial blight (Pseudomonas syringae) and 

bacterial pustule (Xanthomonas campestris); the soybean cyst nematode (Heterodera glycines);

and viral pathogens, soybean mosaic virus and the tobacco ringspot virus (Ruhl, 2007; SSDW, 

No Date). 

Changes in agricultural practices and inputs and natural variations in season, weather, plant 

development stage, geographic location, soil type, and plant species or cultivar can all impact the 

microbial community (Kowalchuk et al., 2003; US-EPA, 2009c). Indirect impacts may result 

from changes in the composition of root exudates, plant litter, or agricultural practices 

(Kowalchuk et al., 2003; US-EPA, 2009c). Several reviews of the investigations into the impact 

of GE plants on microbial soil communities found that most of the studies examining distinctive 

microbial traits concluded that there was either minor or no detectable non-target effects (Hart, 

2006; Kowalchuk et al., 2003; US-EPA, 2009b). Under the No Action Alternative, increases in 

tillage may occur and have an adverse impact on the microbial community.

Water Quality

Surface water in rivers, streams, creeks, lakes, and reservoirs supports everyday life through the 

provision of water for drinking and other public uses, irrigation, and industry. Surface runoff 

from rain, snowmelt, or irrigation water can affect surface water quality by depositing sediment, 

minerals, or contaminants into surface water bodies. Meteorological factors, such as rainfall 

intensity and duration, and physical factors, such as vegetation, soil type, and topography,

influence surface runoff.

97
Groundwater is the water that flows underground and is stored in natural geologic formations 

called aquifers (see Figure 14). It sustains ecosystems by releasing a constant supply of water 

into wetlands and contributes a sizeable amount of flow to permanent streams and rivers. Based 

on 2005 data, the largest use of groundwater in the U.S. is irrigation, representing approximately 

67 percent of all the groundwater pumped each day (McCray, 2009). In the U.S., approximately 

47 percent of the population depends on groundwater for its drinking water supply.

Unlike a point source, which is a “discernible, confined and discrete conveyance,” nonpoint 

source (NPS) pollution comes from many diffuse sources. Rainfall or snowmelt moving over the 

ground, also known as runoff, picks up and carries away natural and human-made pollutants, 

creating NPS pollution. The pollutants may eventually be transported by runoff into lakes, rivers, 

wetlands, coastal waters, and groundwater (see Figure 14).

The primary cause of NPS pollution is increased sedimentation in surface waters following soil 

erosion by surface runoff. Increases in sediment loads to surface waters can directly affect fish, 

aquatic invertebrates, and other wildlife maintenance and survival. It also reduces the amount of 

light penetration in water, which directly affects aquatic plants. Indirectly, soil erosion-mediated 

sedimentation can increase fertilizer runoff, facilitating higher water turbidity, algal blooms, and 

oxygen depletion (US-EPA, 2005a). 

Figure 14. Water Quality

Source (USGS).

Agricultural NPS pollution is the leading source of impacts on surveyed rivers and lakes and the 

third largest source of impairment to estuaries, as well as a major source of impairment to 

groundwater and wetlands (USDA-EPA, 2011). Sources of agricultural NPS pollution include

animal wastes, fertilizers, and pesticides. Management practices that contribute to NPS pollution 

98
include the type of crop cultivated; plowing and tillage; and the application of pesticides, 

herbicides, and fertilizers. 

Use of pesticides for field crop production may introduce these chemicals to water through spray 

drift, cleaning of pesticide application equipment, soil erosion, or filtration through soil to 

groundwater. As part of assessing the risk of the exposure of aquatic organisms and the 

environment to a pesticide, EPA estimates concentrations of pesticides in natural water bodies, 

such as lakes or ponds. Also as part of the Food Quality Protection Act (FQPA) of 1996, EPA 

estimates pesticide concentrations in drinking water when it establishes maximum pesticide 

residues on food (tolerances). For both drinking water and aquatic exposure assessments and for 

water quality assessments, EPA typically relies on field monitoring data as well as mathematical 

models to generate exposure estimates (US-EPA, 2012d). 

Under the No Action Alternative, increased tillage may occur and lead to increases in 

sedimentation and corresponding decreases in water quality.

Irrigation

Water in agriculture is used for irrigation, pesticide and fertilizer applications, crop cooling (e.g., 

light irrigation), and frost control (CDC, 2013). The availability and use of moisture for crop 

irrigation are important determinants of yield. Irrigation can offer a stable supply of adequate 

moisture to the crop, thereby providing a potential for increased yields over dryland production 

and helping stabilize annual fluctuations in yield and seed quality

(http://www.aragriculture.org/soil_water/irrigation/crop/soybeans.htm ). In addition to the total 

amount, the timing of the moisture is important for optimizing crop yields. Water requirements 

are dependent on the type of crop and its stage of development. There are critical periods during 

the growing season when a crop’s soil moisture must be sustained to ensure optimal yields (USEPA, 2012b). Both groundwater and surface water can be used for irrigation water, although 

groundwater is the major source of water for irrigation. Wells commonly provide a source of 

water on farms in many areas and are usually the only source used in the Great Plains (US-EPA, 

2012b). 

Corn is a water-sensitive crop with a low tolerance for drought. The stress response and yield 

loss depends on the stage of the corn growth (Farahani & Smith, 2011). The water demand is 

variable over the growing season, with the greatest water demand during the silk production 

stage in mid-season. During this stage, the water requirement is estimated at about 2 inches of 

water per week (or 0.3 inch per day) (Farahani & Smith, 2011; Heiniger, 2000). Corn requires 

approximately 4,000 gallons through the growing season to produce 1 bushel of grain (NCGA, 

2007a). 

This water demand is met by a combination of natural rainfall, stored soil moisture from 

precipitation before the growing season, and supplemental irrigation during the growing season 

(Farahani & Smith, 2011; Heiniger, 2000). Areas in the U.S. where corn is irrigated is shown in 

Figure 14. Most of the irrigated areas are found in the TX and OK panhandles, KS, NE, and 

along the Southern Mississippi River areas of MO, AR, MS, and LA. Groundwater is used on 

almost 90 percent of irrigated corn acreage in the U.S. (Christensen, 2002). Corn for grain has 

substantially more irrigated area than any other single crop in the U.S. (Christensen, 2002). In 

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2007, 13.0 million U.S. corn acres were irrigated, representing 15 percent of all corn acres 

harvested for grain (USDA-NASS, 2009e). 

Figure 15. Irrigated Corn for Grain

Source (USDA- Census of Agriculture, 2007).

The soils and climate in the Eastern, Midwestern, and portions of the Great Plains region of the 

U.S. provide sufficient water supplies under normal climatic conditions to produce a soybean 

crop. In regions of the U.S. that experience low amounts of rainfall during the growing season or 

during drought, soybean yields benefit from proper irrigation. Soybeans require approximately 

20 to 25 inches of water during the growing season to produce a relatively high yield of 40 to 50 

bushels per acre (Hoeft et al., 2000; KSU, 1997; Nafziger, 2007; University of Arkansas, 2006). 

In 2006 and 2008, approximately 9 percent of the planted acres of soybeans in the U.S. were 

irrigated (USDA-ERS, 2011d; USDA-NASS, 2010a). In 2007, when approximately 6 percent of 

the total soybean crop was irrigated, over 92 percent of the irrigation supply was from 

groundwater supply (USDA-ERS, 2012c). 

As shown in Figure 16, a majority (approximately 73 percent) of irrigated soybean acreage

occurs in the Missouri and Lower Mississippi Water Resource Regions, and soybean acreage in 

the states of Nebraska, Arkansas, Mississippi, Missouri, and Kansas accounts for 85 percent of 

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all irrigated acres (USDA-NASS, 2011c). In 2006, approximately 8.4 inches of water per 

irrigated acre were used, producing an average of more than 51 bushels per irrigated acre 

(USDA-ERS, 2011d). This yield was approximately 19.8 percent higher than the national 

average (42.9 bushels per acre) for that year (USDA-NASS, 2011a). 

Figure 16. Irrigated Soybeans for Beans

Source: (USDA-NASS, 2009e)

Notes: Each dot represents 2,000 acres of irrigated soybeans for beans harvested in 2007. The largest concentrations 

of acres are in Nebraska, eastern Arkansas, and northwestern Mississippi.

Certain weed management practices require either adequate rainfall or irrigation in order to work 

well. Many residual herbicides require water to be activated (Hager et al., 2011). Although the 

use of residual herbicides are recommended for herbicide resistance weed management, in dry

years such as occurred in 2012, residual herbicides were ineffective in areas that lacked rainfall 

and the use of irrigation water.

Corn production has expanded significantly since 2006 to meet biofuel feedstock demand (see 

Figure 8). Wallander et al. (Wallander et al., 2011) estimate that from 2006 to 2008, roughly half 

of the expansion came from acreage shifts from soybean production, one-third came from 

conversion of uncultivated hay and grazing land and from acreage formerly enrolled under the 

USDA Conservation Reserve Program (CRP), and the remainder came from increases in corn 

yields and double cropping and decreases in idled cropland. However, farms shifting from other 

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crops, particularly cotton, offset the shift from soybeans to corn. Production response has varied 

across regions: shifts in crop acreage from soybean to corn acres have been the dominant 

production response in regions B, C, E, and southern region G, while expansion in harvested 

cropland from land formerly used for hay, grazing, and the conservation Reserve Program has 

dominated southern region F, northern region G and regions H and I. Schaible and Aillery 

(Schaible & Aillery, 2012) suggest that the expansion of corn acreage to meet biofuel feedstock 

demand has the “potential for increased reliance on irrigation,” particularly for the Plains States. 

They suggest this would likely involve an increase in consumptive water use, both due to 

expanded irrigated corn acres and because water consumption by corn plants is greater than that 

for soybeans, placing additional pressure on groundwater resources where withdrawals have 

generally exceeded natural recharge. Under the No Action Alternative, the additional pressure on 

groundwater resources are expected to decline as corn production is expected to decline and 

soybean production is expected to expand only slightly (USDA-OCE, 2014). 

Air Quality

Cultivation of corn and soybeans, like any other agricultural system, may affect air quality. 

Primary sources of emissions associated with crop production include exhaust from motorized 

equipment, such as tractors and irrigation equipment; suspended soil particulates from tillage and 

wind-induced erosion; smoke from burning of fields; drift from sprayed herbicides and 

pesticides; and nitrous oxide emissions from the use of nitrogen fertilizer (Aneja et al., 2009; 

Hoeft et al., 2000; USDA-EPA, 2011; USDA-NRCS, 2006a). 

Soybean and cornfields typically are tilled just prior to planting. Tillage not only is associated 

with increased emissions due to burning of fossil fuels but also results in the release of 

particulate matter into the air (Madden et al., 2009). By generating fewer suspended particulates 

(dust), reduced tillage also potentially contributes to lower rates of soil wind erosion, thus 

benefitting air quality (Towery & Werblow, 2010). Although this impact is variable and is 

affected by factors such as soil moisture and specific tillage regime employed, this observation 

demonstrates the role of conservation tillage in reducing particulate matter. Reduced tillage 

minimizes burning of fossil fuels and the production of airborne particulates, both of which are 

major aspects of agricultural practices that affect air quality. The extent to which reduced tillage 

reduces burning of fossil fuels is illustrated in Table 8, based on the NRCS Energy Estimator: 

Tillage Tool (USDA-NRCS, 2013). The tool estimates potential fuel savings of 3,010 gallons or 

60 percent savings per year based upon producing 1,000 acres of no-till soybean compared to 

conventional till soybean in the Urbana, Illinois, postal code8

. NRCS is careful to note that this 

estimate is only approximate because many variables can affect an individual operation’s actual 

8 Postal codes are used in the NRCS Energy Estimator to estimate diesel fuel use and costs in the production of key 

crops for an area.

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savings. However, this example serves to illustrate the magnitude of the contribution of 

minimum tillage to the reducing the impact of agriculture on air quality.

Table 8. Total Farm Diesel Fuel Consumption Estimate

Estimate for 1,000-Acre 

Soybean Crop

(Urbana, Illinois)

Consumption by Tillage Method

(gallons per year)

Conventional 

Tillage

Mulch-till Ridge-till No-till

Total fuel use 4,980 4,110 3,330 1,970

Potential fuel savings over 

conventional tillage -- 870 1,650 3,010

Total savings -- 17% 33% 60%

Source: (USDA-NRCS, 2013)

Prescribed burning is a land treatment, used under controlled conditions, to accomplish resource 

management objectives. Open combustion produces particles of widely ranging size, depending 

to some extent on the rate of energy release of the fire (US-EPA, 2011a). The extent to which 

agricultural and other prescribed burning may occur is regulated by individual State 

Implementation Plans to achieve compliance with the National Ambient Air Quality Standards. 

Prescribed burning of fields would likely occur only as a pre-planting option for soybean 

production, based on individual farm characteristics. Volatilization of fertilizers, herbicides, and 

pesticides from soil and plant surfaces also introduces these chemicals to the air. The USDA

Agricultural Research Service (ARS) is conducting a long-term study to identify factors that 

affect pesticide levels in the Chesapeake Bay Region airshed (USDA-ARS, 2011). This study 

has determined volatilization is highly dependent on exposure of disturbed unconsolidated soils,

and variability in measured compound levels is correlated with temperature and wind conditions. 

Another ARS study of volatilization of certain herbicides after application to fields has found 

moisture in dew and soils in higher temperature regimes significantly increases volatilization 

rates (USDA-ARS, 2011). 

Pesticide and herbicide spraying may impact air quality through both drift and diffusion. 

Pesticides are typically applied to crops by ground spray equipment or aircraft. Small, 

lightweight droplets are produced by equipment nozzles; many droplets are small enough to

remain suspended in air for long periods allowing them to be moved by air currents until they 

adhere to a surface or drop to the ground. The amount of drift varies widely and is influenced by 

a range of factors, including weather conditions, topography, the crop or area being sprayed, 

application equipment and methods, and practices followed by the applicator. Drift is defined by 

EPA as: “the movement of pesticide through air at the time of application or soon thereafter, to 

any site other than that intended for application” (Kiely et al., 2004). 

Diffusion is gaseous transformation to the atmosphere (Owen, 2008). Factors affecting drift and 

diffusion include application equipment and method, weather conditions, topography, and the 

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type of crop being sprayed (Kiely et al., 2004). EPA’s Office of Pesticide Programs (OPP), 

which regulates the use of pesticides and herbicides in the U.S., encourages pesticide applicators 

to use all feasible means available to them to minimize off-target drift. EPA-OPP has introduced 

several initiatives to help address and prevent the problems associated with drift. Currently, 

EPA-OPP is evaluating new regulations for pesticide drift labeling and the identification of

BMPs to control such drift (US-EPA, 2009c), as well as identifying scientific issues surrounding 

field volatility of conventional pesticides (US-EPA, 2010c). Additionally, EPA-OPP and its 

Office of Research and Development are developing a new voluntary program, the Drift 

Reduction Technology Program, which encourages the development, marketing, and use of 

application technologies verified to significantly reduce spray drift (US-EPA, 2009c). Additional 

information on off-target movement of pesticides is included in Appendix 7. 

Other conservation practices, as required by USDA to qualify for crop insurance and beneficial 

federal loans and programs (USDA-ERS, 2009a), effectively reduce crop production impacts to 

air quality through the employment of windbreaks, shelterbelts, reduced tillage, and cover crops 

that promote soil protection on highly erodible lands. 

Under the No Action Alternative, increased tillage and pesticide use is expected to occur to 

manage HR weeds. These more intensive management practices are expected to have adverse 

impacts on air quality.

Climate Change

Climate change represents a statistical change in global climate conditions, including shifts in the 

frequency of extreme weather (Cook et al., 2008). EPA has identified carbon dioxide (CO2), 

methane (CH4), and nitrous oxide (N2O) as the key greenhouse gases (GHGs) affecting climate 

change. During the 20-year period of 1990 to 2009, total emissions from the agricultural sector 

grew by 8.7 percent with 7 percent of the total U.S. GHG emissions in 2009 generated from this 

sector (US-EPA, 2011c).

For agriculture and natural resources, the main GHGs of concern are carbon dioxide, methane 

and nitrous oxide. Emissions of GHGs released from agricultural equipment (e.g., irrigation

pumps and tractors) include carbon monoxide, nitrogen oxides, methane (CH4), reactive organic 

gases, particulate matter, and sulfur oxides (US-EPA, 2011c). Agricultural soil management 

practices, including nitrogen-based fertilizer application and cropping practices, represent the 

largest source of U.S. N2O emissions; croplands account for 69 percent of the total N2O 

emissions attributable to agricultural land uses (US-EPA, 2011c). Agricultural sources of 

methane emissions are associated primarily with enteric emissions of gas from cattle and manure 

management. Carbon dioxide also is a significant GHG associated with several agricultural 

practices, including land uses and energy consumption (US-EPA, 2011c). 

The contribution of agriculture to climate change largely is dependent on the production 

practices employed to grow various commodities, the region in which the commodities are 

grown, and the individual choices made by growers. The same factors associated with 

conventional crop production also determine the impacts of GE crop varieties on climate change. 

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Conversion of crop land to pasture results in an increase in carbon and nitrogen sequestration in 

soils (US-EPA, 2011a). Agricultural lands afford great opportunities for sequestering carbon 

(reducing carbon dioxide levels) and reducing or mitigating emissions of other GHGs. Efforts to 

quantify and encourage such actions are on-going efforts in the Natural Resources Conservation 

Service (NRCS).

Global climate change may also affect agricultural crop production (Backlund, 2008). These 

potential impacts on the agro-environment and individual crops may be direct, including 

changing patterns in precipitation, temperature, and duration of growing season, or may cause 

indirect impacts influencing weed and pest pressure (Rosenzweig et al., 2001; Schmidhuber & 

Tubiello, 2007). A recent Intergovernmental Panel on Climate Change (IPCC) forecast (IPCC, 

2007) for aggregate North American impacts on agriculture from climate change projects yield 

increases of 5 to 20 percent for this century. The IPCC report notes that certain regions of the 

U.S. will be more adversely impacted because water resources may be substantially reduced. In

addition, the current range of weeds and pests of agriculture is expected to change in response to 

climate change (USGCRP, 2009). While agricultural impacts on existing crops may be 

substantial, North American production is expected to adapt with improved cultivars and 

responsive farm management (IPCC, 2007).

Under the No Action Alternative, cropping practices to manage weeds in corn and soybean will 

likely increase in intensity. Control of glyphosate resistant weeds will likely require increased 

use and applications of of herbicides together with increased use of tillage (see sections 4.1.1 

tillage and 4.1.1 herbicides and Appendix 4). Consequently corn and soybean cultivation will 

result in greater GHG emissions from the use of fossil fuels to apply herbicides and to till fields. 

The manufacture of herbicides may also contribute to the release of greenhouse gases but the 

overall contribution is likely to be a minor contribution. The magnitude of the effect will depend 

on the HR weed management practices that growers choose to use.

4.2 Preferred Alternative

Under the Preferred Alternative, APHIS would approve all three petitions for nonregulated 

status. These corn and soybean events and their progeny could be grown and shipped without a 

permit from APHIS BRS. This section analyzes the impacts of that decision. Here we consider 

the direct and indirect effects of that decision on the human environment. In general, the direct 

and indirect impacts on each resource for the Preferred Alternative are the same as for the No 

Action Alternative because EnlistTM corn and soybean have nearly identical properties as other

GE and conventional corn and soybeans. The primary impacts from the EnlistTM technology on 

each resource derive from herbicide use and these impacts are outside the scope of this EIS 

because EPA is the federal authority responsible for the analysis of these impacts and thoroughly 

analyzes them elsewhere (US-EPA, 2013a; b; c; 2014). EPA has shared their risk assessments 

with USDA and they are cited but not further analyzed in this document. In the past, EPA risk 

assessments have not included an analysis of the potential for selection of HR weeds and 

resulting impacts so this analysis is included in this FEIS. This analysis of HR weeds is 

considered in the cumulative impacts section in Chapter 5 because it only arises from the joint 

action of both APHIS’ approval of the three petitions and EPA’s pending decisions on the use of 

certain pesticides on these events. 

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4.2.1 Socioeconomic and Human Health

Land Use

Under the Preferred Alternative there would be no direct or indirect effects on land use that result 

from the decision to approve the petitions, as compared with the No Action Alternative. The 

drivers of land used for corn and soybean production include the price of corn and soybean and 

the suitability of the land for this production. Prices of these commodities have risen in recent 

years, although 2013 saw a decline in the price of corn. The decision to approve these petitions 

will not affect the demand for corn or soybean. Acreage is expected to decline for corn 

production and remain high for soybean production over the next few years (USDA-OCE, 2014)

regardless of the decision made by APHIS on these three petitions. 

Like the No Action Alternative, under the Preferred Alternative, growers of specialty value 

added corn and soybean crops would see production and demand for these value added crops 

unchanged by nonregulated status for the three varieties.

Domestic Use of Corn and Soybean in the U.S. Economy

Under the Preferred Alternative there would be no direct or indirect effects on the use of corn or 

soybean in the U.S. economy. According to the petitions, each of the events is compositionally 

similar to currently available varieties of corn and soybean. These events would be suitable for 

use in food, feed, and industrial applications of corn and soybean products. Therefore the use of 

these events in corn or soybean processes would not change when compared to the No Action 

Alternative.

Corn and Soybean Agronomic Practices and Costs of Production

Under the Preferred Alternative there would be no direct or indirect effect on corn or soybean 

agronomic practices or the cost of production because currently growers cannot use any 

herbicides differently on EnlistTM corn or soybean than are available to them for other corn and 

soybean varieties. That is because Enlist DuoTM is not registered for use on these corn or soybean 

events until EPA approves the label. EPA regulates the use of herbicides under FIFRA and is 

making a separate decision which may or may not allow its use on these plants. Therefore, the 

types of agronomic practices used to control weeds in these varieties would be similar to those 

used in other available varieties. Growers would continue to manage weeds using a combination 

of chemical and cultural methods. HR weeds would be selected for by management practices in 

the same ways that they are in the No Action Alternative. Under this alternative, like the No 

Action Alternative, growers may rely on glyphosate to manage weeds in corn and soybean. 

Weed scientists will continue to encourage growers to use best management practices like under 

the No Action Alternative.

Export of Corn and Soybean

A determination of nonregulated status of DAS-40278-9 corn, DAS-68416-4 soybean, and DAS4406-6 soybean are not expected to adversely impact trade under the Preferred Alternative. Dow

106
has submitted applications to several international agencies, including the regulatory authorities 

in Canada, Brazil, Australia, New Zealand, China, Colombia, EU, Japan, Korea, South Africa, 

and Switzerland (Orr, 2013) . Approvals for one or more of the EnlistTM crops have occurred in 

some countries and are pending in others. Regulatory status as of July 8, 2014 is summarized in 

Table 9. Although the primary U.S. corn and soybean export destinations do not present major 

barriers to trade in GE products, Dow would need to obtain approval of DAS-40278-9 corn, 

DAS-68416-4 soybean, and DAS-4406-6 soybean in destination countries before

commercialization to avoid adversely affecting current trade flows. 

Table 9. Current Approval Status (as of July 8, 2014) of DAS-40278-9 Corn, DAS-68416-4 

Soybean, and DAS-44406-6 Soybean in Various Countries

Country

DAS-40278-9

Corn

DAS-68416-4

Soybean

DAS-44406-6

Soybean

Canada (Food/Feed/Cultivation) approved approved approved

Argentina 

(Food/Feed/Cultivation) pending pending pending

Brazil (Food/Feed/Cultivation) pending pending pending

ANZ (Food/Feed) approved approved approved

China (Food/Feed) pending pending pending

Colombia (Feed) approved approved pending

Colombia (Food) approved pending pending

EU (Food/Feed) pending pending pending

Japan (Food/Feed/Cultivation) approved pending pending

Korea (Food/Feed) approved pending pending

Mexico (Food/Feed) approved approved approved

South Africa (Food/Feed) approved pending approved

Switzerland (Food/Feed) pending pending pending

USA (Food/Feed) approved approved approved

USA (Cultivation) pending pending pending

Source: (DAS, 2013a)

APHIS acknowledges that there may be a requirement in some export markets to test for the 

presence of GE corn or soybean. Testing may be required if these corn or soybean events are not 

approved by the importing country, or for non-GM, identity-preserved corn or corn flour 

shipments (Frank Spiegelhalter, Eurofins, Pers. Comm.). DNA-based polymerase chain reaction 

(PCR) testing would be done in these cases. If a new DNA-based PCR test would be required for 

EnlistTM crops, at an estimated cost of between $300-500 per barge (1500 MT), there would be a 

10 to15 percent increase in current testing costs (Spiegelhalter, Pers. Comm).

Based on these factors, the trade economic impacts associated with a determination of 

nonregulated status of EnlistTM corn and soybean are anticipated to be very similar to the No 

Action Alternative for the bulk of U.S. corn exports, with the exception of a small non-GE, 

identity-preserved export market, where the costs of testing are likely to increase.

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Food and Feed

The direct and indirect effects on food and feed will not be different under the Preferred 

Alternative when compared to the No Action Alternative. People will continue to consume cornand soybean-based products as well as animal products from livestock fed corn and soybean

products. As described in the petition, EnlistTM corn and soybean are compositionally similar to 

currently available varieties of corn and soybean. Therefore, they are not expected to have 

different nutritional qualities than other available corn or soybean varieties. 

Dow has provided the FDA with information on the identity, function, and characterization of 

the genes for DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean. Dow has 

completed consultations with FDA for all three EnlistTM products: DAS-40278-9 corn (US-FDA, 

2011b) , DAS-68416-4 soybean (US-FDA, 2011b), and DAS-44406-6 soybean (US-FDA, 

2013a). The AAD-1 protein in DAS-40278-9 corn is derived from the common gram-negative 

soil bacterium Sphingobium herbicidovorans (Herman et al., 2010). Sphingobium is a member of 

the sphingomonads, a widely distributed bacteria group isolated from soil and water as well as 

plant root systems (DAS, 2009; 2010b). The sphingomonads have been used widely in 

biotechnology applications, including bioremediation of environmental contaminations as well as 

production of sphingans, bio-based polymers which are used in the food industry (DAS, 2010a; 

Lal et al., 2006; Pollock & Armentrout, 1999).

The AAD-12 protein in DAS-68416-4 and DAS-44406-6 soybean is derived from the common 

gram-negative soil bacterium Delftia acidovorans. D. acidovorans is non glucose-fermenting, 

gram-negative, non-spore-forming rod type bacterium present in soil, fresh water, activated 

sludge, and clinical specimens. It has a history of safe use in the food processing industry, 

including having been used in transforming ferulic acid into vanillin and related flavor 

metabolites (DAS, 2010a). Because the AAD-12 protein has a safe history of use in food 

processing, there are not likely to be any effects on food and feed from growing EnlistTM soybean 

when compared to the No Action Alternative.

The pat gene is derived from Streptomyces viridochromogenes, a gram-positive soil bacterium. 

The pat gene conveys resistance to glufosinate (Wohlleben et al., 1988). The PAT protein in 

DAS-68416-4 and DAS-44406-6 soybean is the same as that used as a selectable marker during 

development and to confer herbicide resistance in other previously deregulated GE crops 

(Brenner et al., 2001; Duke & Powles, 2008; USDA-ERS, 2005; USDA-FAS, 2004). 

Additionally, FDA has previously reviewed submissions regarding the safety of food and feed

derived from crops containing the pat gene (BNFs 000055, 000073, 000081, 000085, and 

000092). Because of the similarity of the PAT protein expressed in DAS-68416-4 and DAS44406-6 and the other varieties noted above, there are not likely to be any effects on food and 

feed from growing of EnlistTM soybean when compared to the No Action Alternative.

The mepsps gene in DAS-44406-6 is derived from Zea mays, corn. It contains two mutations 

which convey resistance to glyphosate (Lebrun & Leroux, 1996; Lebrun et al., 2003). It is 

similar to the epsps gene expressed in GA21 corn 

http://www.aphis.usda.gov/brs/aphisdocs/97_09901p.pdf, GHB614 cotton 

http://www.aphis.usda.gov/brs/aphisdocs/06_33201p.pdf, and HCEM485 corn (Stine, 2011).

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GA21 corn (BNF 51), GHB614 cotton, (BNF 109), and HCEM485 corn (BNF 106) have 

completed consultations with FDA. Because of the similarity of the EPSPS protein expressed in 

DAS-44406-6 soybean and the corn and cotton varieties noted above, there are not likely to be 

any effects on food and feed from growing of DAS-44406-6 soybean when compared to the No 

Action Alternative.

Worker Safety

APHIS has not identified any direct or indirect effects on worker safety that would result from 

choosing the Preferred Alternative. Hazards to workers occurring through the various 

management practices that are used to grow corn and soybean are the same as those under the No 

Action Alternative. Choosing the Preferred Alternative will not result in a change in management 

practices when compared to the No Action Alternative with the exception that different 

herbicides will be used, tillage may be less frequent, and farm equipment may be used less often. 

Workers will continue to use farm equipment and agricultural chemicals. The decision to 

approve the three petitions does not authorize a change in herbicide use on these corn or soybean

varieties. EPA regulates the use of herbicides under FIFRA. EPA considers the effects on human 

health when approving the use of herbicides. (See Appendix 8 for a discussion of EPA’s 

assessment).

4.2.2 Biological Resources

Animals

Under the Preferred Alternative, the direct and indirect effects of approving these three petitions 

would be similar to the effects on animals under the No Action Alternative. Animals would 

continue to feed on corn and soybean in the field. DAS-40278-9 corn, DAS-68416-4 soybean

and DAS-44406-6 soybean are compositionally similar to other commercially available corn and 

soybean varieties. As discussed in “Food and Feed” the PAT and mEPSPS proteins are found in 

commercial varieties of corn, cotton, and soybeans. Organisms that feed on these crops are 

exposed to these proteins in previously deregulated varieties with no documented negative 

effects. 

The aad-1 gene, which expresses the AAD-1 protein, was derived from the gram negative soil 

bacterium Sphingobium herbicidovorans (DAS, 2010a). The Sphingobium spp. is a member of 

the sphingomonads, a widely distributed bacteria group isolated from soil and water as well as 

plant root systems (DAS, 2009; 2010a). The sphingomonads have been used widely in 

biotechnology applications, including bioremediation of environmental contaminations as well as 

production of sphingans, bio-based polymers which are used in the food industry (DAS, 2010a; 

Lal et al., 2006; Pollock & Armentrout, 1999). The aryloxyalkanoate dioxygenase proteins,

including AAD-1, are a class of enzymes found in these soil bacteria; hence there has been 

animal exposure to these bacteria and enzymes through normal dietary intake of vegetation and 

incidental ingestion of soil (ANZFS, 2010; 2011; DAS, 2009; 2010a). Dow has presented 

evidence of phenotypic and agronomic trials conducted in 27 locations in the U.S. and Canada 

(DAS, 2010a). The trials evaluated incidences of insect and disease damage between the DAS40278-9 corn variety and other corn hybrids (DAS, 2010a). No statistical differences were noted 

109
between the varieties (DAS, 2010a). Insects, particularly insects which feed on corn, were not 

impacted by ingesting corn in which the aad-1 gene was incorporated. 

DAS has evaluated the potential allergenicity and toxicity of the AAD-1 protein following the 

weight-of-evidence approach (DAS, 2010a). The AAD-1 protein does not share any meaningful 

amino acid similarities with known allergens. The AAD-1 protein is degraded rapidly and 

completely in simulated gastric fluids and the protein is not present in a glycosylated state (DAS, 

2010a). The protein does not share any amino acid sequence similarities with known toxins 

(DAS, 2010a). The results presented by Dow suggest that the AAD-1 protein is unlikely to be a 

toxin in animal diets. Based on a review of this information, APHIS has found no evidence that 

the presence of the aad-1 gene or the expression of the AAD-1 protein would have any impact 

on animals, including animals beneficial to agriculture (USDA-APHIS, 2010b).

Dow evaluated the potential allergenicity and toxicity of the AAD-12 protein following the 

weight-of-evidence approach (DAS, 2010a). The AAD-12 protein does not share any meaningful 

amino acid similarities with known allergens. The AAD-12 protein is degraded rapidly and 

completely in simulated gastric fluids, and the protein is not present in a glycosylated state 

(DAS, 2010a). The protein does not share any amino acid sequence similarities with known 

toxins (DAS, 2010a). The results presented by Dow suggest that the AAD-12 protein is unlikely 

to be a toxin in animal diets. Based on a review of this information and the assumption that these 

studies serve as surrogates for direct testing, APHIS has found no evidence that the presence of 

the aad-12 gene or the expression of the AAD-12 protein would have any impact on animals, 

including animals beneficial to agriculture (USDA-APHIS, 2012a). 

As described in the No Action Alternative, animals can also be impacted indirectly by 

agricultural practices, such as tillage. Adopting the Preferred Alternative will not result in any 

changes in agricultural practices. Growers will continue to use herbicides and cultural practices 

to manage weeds. Increases in tillage to control weeds can increase soil erosion and the indirect 

impacts on wildlife. Agricultural production of corn and soybean would use EPA-registered 

pesticides, including glyphosate, glufosinate, and 2,4-D, for weed management. The 

environmental risks of pesticide use on wildlife and wildlife habitat are assessed by EPA in the 

pesticide registration process and are regularly reevaluated by EPA for each pesticide to maintain 

its registered status under FIFRA.

Plant Communities

Under the Preferred Alternative, the direct and indirect effects of approving these three petitions 

would be similar to the effects on plants under the No Action Alternative. Choosing the Preferred 

Alternative would not change the structure of the plant communities in or around corn and 

soybean fields. Management practices such as herbicide use and mechanical cultivation can 

select for weeds that are adapted to these management practices. Non-target plant communities 

in areas surrounding production fields would be exposed to the effects associated with 

agricultural production, including exposure to various inputs including herbicides. This can 

select for resistance to herbicides among these populations, just as in production fields, resulting 

in establishment of novel resistant biotypes. Exposure to herbicide, e.g., through drift could also 

lead to plant population shifts in non-target populations, just as it could in weed populations 

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associated with production fields. This exposure is the same under the Preferred Alternative and 

the No Action Alternative because approving the three petitions does not directly or indirectly 

change the use of herbicides in corn and soybean. Therefore there are no changes to the effects 

under the Preferred Alternative when compared to the No Action Alternative. While DAS40278-9 corn, DAS-68416-4 soybean and DAS-44406-6 soybean can resist the application of the 

Enlist DuoTM herbicide, this decision does not allow for its use on these corn and soybean 

varieties. EPA regulates the use of herbicides under FIFRA and is making a separate decision 

which may or may not allow its use on these plants. APHIS considers the potential impacts on 

plant communities of its decision combined with EPA’s decision in Chapter 5.

4.2.3 Natural Resources

Soil Quality

The effects on soil quality of choosing the Preferred Alternative are no different than the effects 

under the No Action Alternative. Soil quality is affected by agricultural management practices. 

One factor that is driving agricultural practices is weed management. Growers in the South, 

regions D and F, are using more tillage to manage weeds (Prostko, 2013; Wright & Wimberly, 

2013). Increases in tillage can lead to more soil loss due to erosion USDA-NRCS 1996). 

Additionally, the trend toward increased herbicide use to control herbicide-resistant weeds in 

different cropping systems (Culpepper, 2008; Heap, 2011b; Owen & Zelaya, 2005; Owen, 2008)

will be similar under the No Action and the Preferred Alternative. Pesticide use has the potential 

to affect soil quality due to the impact to the soil microbial community. 

The decision to approve these petitions will not directly or indirectly affect these grower 

decisions to use tillage to manage weeds. Approving the petitions would allow these varieties to 

be planted, but it does not allow for the use of the Enlist DuoTM herbicide on the plants. The use 

of Enlist DuoTM is regulated by EPA. EPA regulates the use of herbicides under FIFRA and is 

making a separate decision which may or may not allow its use on these plants. APHIS considers 

the potential cumulative impacts on soil of its decision combined with EPA’s decision in Chapter 

5.

Water Quality

Agricultural practices can affect water quality. Under the Preferred Alternative agricultural 

impacts on water quality are the same as those described under the No Action Alternative. 

Choosing the Preferred Alternative does not change the way people will grow corn and soybeans 

or manage weeds in their fields. In areas where tillage is used to control weeds and soil erosion 

occurs, water may be affected by sediment (Robertson et al., 2009).

Use of pesticides for field crop production may introduce these chemicals to water through spray 

drift, cleaning of pesticide application equipment, soil erosion, or filtration through soil to 

groundwater. As part of assessing the risk of the exposure of aquatic organisms and the 

environment to a pesticide, EPA estimates concentrations of pesticides in natural water bodies, 

such as lakes or ponds. Also as part of the Food Quality Protection Act (FQPA) of 1996, EPA 

estimates pesticide concentrations in drinking water when it establishes maximum pesticide 

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residues on food (tolerances). For both drinking water and aquatic exposure assessments and for 

water quality assessments, EPA typically relies on field monitoring data as well as mathematical 

models to generate exposure estimates (US-EPA, 2012d). 

Approving the petitions would allow these varieties to be planted, but it does not allow for the 

use of the Enlist DuoTM herbicide on the plants. The use of Enlist DuoTM is regulated by EPA. 

EPA regulates the use of herbicides under FIFRA and is making a separate decision which may 

or may not allow its use on these plants. APHIS considers the potential impacts on water quality 

of its decision combined with EPA’s decision in Chapter 5.

Air Quality

Agricultural activities such as tillage, pesticide application, prescribed burning, and farm 

equipment use can all effect air quality. Growers choose those activities that are most suited for 

their operations. To manage weeds growers may use a combination of activities including 

pesticide use. In some areas of the south tillage is increasing under the No Action Alternative. 

This activity indirectly affects air as particulate matter can increase with increasing tillage. Also 

conventional tillage can use more fossil fuels than conservation tillage methods (Table 8). 

Choosing the Preferred Alternative will not directly affect grower’s management choices. 

Approving the petitions would allow these varieties to be planted, but it does not allow for the 

use of the Enlist DuoTM herbicide on the plants. The use of Enlist DuoTM is regulated by EPA. 

EPA regulates the use of herbicides under FIFRA and is making a separate decision which may 

or may not allow its use on these plants. APHIS considers the potential impacts on air quality of 

its decision combined with EPA’s decision in Chapter 5.

Climate Change

The same types of agricultural activities that effect soil, water and air quality can contribute to 

climate change. As discussed in those other areas, choosing the Preferred Alternative does not 

change these production practices. Therefore the effects on climate change are the same under 

the preferred and the No Action Alternative.

4.3 Alternative 3

Under Alternative Three, which approves Petition 09-233-01p, DAS-40278-9 corn, but not 

Petitions 09-349-01p or 11-234-01p for Dow soybean, the impacts are similar to those described 

in the Preferred Alternative. Approving the petition would allow the corn variety to be planted 

without a permit or acknowledged notification. The two soybean lines would continue to be 

regulated. This decision does not allow for the use of the Enlist DuoTM herbicide on the corn 

plants. The use of Enlist DuoTM is regulated by the EPA. The EPA regulates the use of herbicides 

under FIFRA and is making a separate decision which may or may not allow its use on these 

plants. APHIS considers in Chapter 5 the potential impacts of its decision under Alternative 3

combined with the EPA’s decision to register Enlist DuoTM.

Because approving all three petitions would not have different effects on natural or biological 

resources than the No Action Alternative, approving one of the three EnlistTM crops is also not 

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expected to have different direct and indirect effects on those resource areas. In addition, APHIS 

does not expect Alternative 3 to have different socioeconomic or human health related effects 

than the Preferred Alternative because the approval of petition 09-233-01p is one of the petitions 

considered in Alternative 2 and no direct or indirect effects of growing DAS-40278-9 corn were 

identified in that Alternative when compared to the No Action Alternative.

4.4 Alternative 4

Under Alternative Four, which approves Petitions 09-349-01p or 11-234-01p for Dow soybean 

but not Petition 09-233-01p for DAS-40278-9 corn, the impacts are similar to those described in 

the Preferred Alternative. Approving the petition would allow the soybean varieties to be planted 

without a permit or acknowledged notification. The corn event would continue to be regulated. 

This decision does not allow for the use of the Enlist DuoTM herbicide on the soybean plants. The 

use of Enlist DuoTM is regulated by the EPA. The EPA regulates the use of herbicides under 

FIFRA and is making a separate decision which may or may not allow its use on these plants. 

APHIS considers the potential impacts of its decision under Alternative 4 combined with the 

EPA’s decision on Enlist DuoTM in Chapter 5.

Because approving all three petitions would not have different effects on natural or biological 

resources than the No Action Alternative, approval of two of the three EnlistTM crops is also not 

expected to have different direct and indirect effects on those resource areas. In addition, APHIS 

does not expect Alternative 4 to have socioeconomic or human health related effects different 

than the Preferred Alternative because the approval of petitions 09-349-01p or 11-234-01p are 

two of the petitions considered in Alternative 2 and no direct or indirect effects of growing DAS

soybeans were identified in that alternative when compared to the No Action Alternative.

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5 CUMULATIVE IMPACTS

This section assesses current and reasonably foreseeable future impacts if APHIS chooses one of 

the Action Alternatives (Alternative 2, 3, or 4). APHIS considers the impacts of the Action 

Alternative combined with its past, present, and reasonably foreseeable future actions, as well as 

those actions of others in this section.

Cumulative impacts are defined as the “impact on the environment, which results from the 

incremental impact of the action when added to other past, present, and reasonably foreseeable 

future actions regardless of what agency (federal or non-federal) or person undertakes such other 

actions” (40 CFR 1508.7).

Impacts on natural and biological resources were considered in the analyses. Possible 

implications of how these impacts might affect the availability of those resources for human use 

and consumption were also analyzed. The initial step in this process was an analysis of the 

potential changes in management practices likely to occur if APHIS approves one or more of the 

Dow petitions, and EPA approves the application rate changes for 2,4-D on GE corn and 

soybean requested by the petitioner. In the second phase, the way changes in management 

practices might impact natural and biological resources were analyzed. Possible impacts of an 

interaction with other APHIS actions (past and those currently pending) were also considered.

Environmental issues were assessed individually in Section 4. From that analysis, APHIS 

determined there are no direct or indirect impacts from DAS-40278-9 corn, DAS-68416-4 

soybean, and DAS-44406-6 soybean, because these varieties are not agronomically different 

from other GE corn or soybean cultivars that are no longer regulated by the Agency. However, 

the analysis did not consider potential cumulative impacts that might result if the requested EPA 

actions are approved in conjunction with those of APHIS. An APHIS determination of 

nonregulated status for DAS-40278-9 corn, DAS-68416-4 soybean, or DAS-44406-6 soybean, 

and the independent action by EPA to approve registration of Enlist DuoTM on these crops is 

reasonably foreseeable. . This herbicide product contains choline formulations of 2,4-D together 

with glyphosate. It is specifically formulated for use on the crops that are the subject of this EIS.

The factors that contribute to increased 2,4-D use on corn and soybean include the application 

rate (i.e. the pounds applied per acre)9 and the number of acres to which 2,4-D is applied. For 

corn, the maximum application rate of 2,4-D is the same for EnlistTM corn and other corn 

varieties. However, for EnlistTM corn, more acres of corn are expected to be sprayed with 2,4-D. 

For soybean, the new label would allow for higher application rate and applications at later 

stages of plant growth than currently approved for 2,4-D use on soybean. In addition, more 

soybean acres are likely to be sprayed with 2,4-D with EnlistTM soybean than for other varieties. 

Therefore, one possible cumulative impact is that more 2,4-D will be applied to corn and 

9 For the application rate there is a maximum rate allowed per application and a total seasonal use rate which is the 

maximum pounds/acre that can be applied in a season. See Appendix 4 for more details.

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soybean crops, resulting in increased selection for 2,4-D resistant weeds. Because this impact 

would occur only if both APHIS and EPA take the actions already described here, APHIS has 

analyzed the potential cumulative impacts of its action combined with potential Enlist DuoTM 

applications in more detail in this section. More specifically, this cumulative impacts section 

analyzes the cumulative impact of weed resistance due to the cumulative use of 2,4-D over time. 

It includes a discussion of potential cumulative impacts associated with the Action Alternatives 

(see Section 2), when combined with other past, present, and reasonably foreseeable future 

actions within the affected environment (described in Section 3).

5.1 Cumulative Impacts Methodology

For this analysis, Alternative 1, the No Action Alternative was the baseline for comparisons. 

Under Alternative 1, DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean 

could only be grown if regulated under APHIS notifications or permits. Under this circumstance, 

it is possible that EPA would still approve choline formulations for use on corn and burndown 

applications in soybean. APHIS assumes that currently available formulations of 2,4-D would 

also be available as would currently available varieties of corn and soybean.

5.2 Geographic Boundaries for the Analysis of Cumulative Effects

APHIS evaluated impacts at the regional and national levels for this analysis. Regional levels 

included the ecoregions defined in Section 3 (Affected Environment). The national level is the 

conterminous U.S. states as little corn is grown outside the 48 states. 

5.3 Management Practices Considered in the Analysis of Cumulative Impacts

This analysis addresses the potential impacts of the Alternatives on natural and biological 

resources and their interrelated socioeconomic impacts within the U. S. DAS-40278-9 corn, 

DAS-68416-4 soybean, or DAS-44406-6 soybean do not affect natural or biological resources 

directly, but the management practices (e.g., pesticide applications) associated with cultivation of 

these crops impact natural and biological resources. If EPA registers Enlist DuoTM for DAS40278-9 corn, DAS-68416-4 soybean or DAS-44406-6 soybean, APHIS expects that 2,4-D use 

will increase under the Preferred Alternative. Increased use of 2,4-D could accelerate the

selection and distribution of 2,4-D-resistant weeds. As a result, growers of other crops that use 

2,4-D for weed control may need to modify their management practices to delay or manage 2,4-

D resistant weeds. These changes would increase the complexity and cost of weed management 

programs for these growers. Because the use of DAS-40278-9 corn, DAS-68416-4 soybean or 

DAS-44406-6 soybean does not require a single specific set of agronomic practices, the 

magnitude of the impacts discussed depend on the adoption rates of various practices by 

growers. This section analyzes the cumulative impacts related to changes in management 

practices that are likely to be associated with the adoption of DAS-40278-9 corn, DAS-68416-4 

soybean or DAS-44406-6 soybean in the context of the impacts that agriculture has on these 

resources in the areas where corn and soybeans are grown.

5.4 Risk Assessments Used for the Analysis of Cumulative Impacts

The EPA uses risk assessment for registration decisions. It evaluates risk based on exposure and 

hazard to both humans and other organisms. A pesticide cannot be registered, nor can an existing 

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registration be amended, unless the registered use conforms to the EPA standard of “no

unreasonable adverse effects on the environment” as described in FIFRA. There are four general 

steps in the risk assessment process: hazard identification, exposure assessment, dose/response 

assessment, and risk analysis. Once the EPA determines that this standard can be met, it issues a 

registration or modifies an existing one. The registration label includes strict limits on the 

quantities and methods allowed for the use of a pesticide to ensure that the standard is met.

The EPA has developed exposure assessments for this process to characterize environmental 

persistence of pesticides and their byproducts from degradation following application. These 

assessments are based in part on scientific studies that sample and measure residue 

concentrations for specified time frames. The data are analyzed with statistical procedures 

referred to as models to extrapolate estimates for environmental fate (i.e., persistence of residues) 

over longer time frames than the ones sampled.

The EPA uses environmental fate data to predict potential concentration of the pesticide and its 

degradation products in air, soil, and surface and groundwater. These data are also used to 

estimate residue levels in the drinking water component of human dietary risk assessments.

Results of environmental fate studies enable the EPA to determine where a pesticide and its 

degradates (byproducts) go in the environment (i.e., air, water, and soil), how long they persist,

and in what quantities. This information is used by the EPA to develop estimated environmental 

concentrations (EECs) that can be compared to toxicity and ecotoxicology data as part of the risk

assessment process. EEC values are based on the maximum allowable application rate for a

pesticide although typical application rates are usually lower than the maximum allowed. This 

approach, along with other factors such as the conditions on the farm field, result in “high-end” 

to “bounding” estimates of exposure. When these are compared to the most sensitive 

toxicological endpoints in human and ecological effects studies, the results are conservative risk 

estimates. If these estimates exceed concern levels, the EPA will refine the exposure estimates 

using additional information or may perform a probabilistic assessment of risks. The EPA has 

conducted independent assessments of direct and indirect effects associated with the use of 2,4-D 

on DAS-40278-9 corn, DAS-68416-4 soybean, or DAS-44406-6 soybean concurrent with the 

development of this EIS (US-EPA, 2013a; b; c). These effects are outside the scope of this EIS. 

In the proposed registration, the EPA has established label restrictions for the use of Enlist 

DuoTM on EnlistTM crops that, when followed, will ensure no unreasonable adverse effects to 

human health or the environment associated. APHIS’ analysis in this section focuses on 

cumulative impacts associated with these varieties, including the development of HR weeds, due 

to herbicide application and changes in management practices resulting from their use.

5.5 Magnitude of Potential Impacts on Resources

APHIS identified changes in management practices that could cause impacts on natural and 

biological resources. If approved for general use, the degree to which the varieties that are the 

subject of this EIS are adopted will determine the magnitude of the impacts of the associated new 

management practices. Because APHIS does not regulate production/management practices, it 

cannot control them. 

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5.6 Assumptions

A summary of the assumptions made for the analyses included in this section follow:

• The APHIS PPRA did not identify any changes in DAS-40278-9 corn, DAS-68416-4 

soybean, or DAS-44406-6 soybean that would directly or indirectly affect natural or 

biological resources. These plants are compositionally similar to other corn and soybean 

plants. The growth habit of the plants is also similar to other corn and soybean plants. 

APHIS assumes that growers will choose management practices appropriate for the crops 

planted. APHIS used information available from extension services, trade journals, 

scientific journals, and public comments for petitions to identify common practices.

• GE HR corn and soybean varieties will continue to be planted under all of the 

alternatives. Most of the U.S. corn and soybean acreage is currently planted in GE HR 

varieties.

• Under Alternatives 2, 3, and 4, DAS 40278-9 corn, DAS 68416-4 soybean, or DAS

444406-6 soybean , the deregulated EnlistTM crops could be crossed with any currently 

available variety including GE varieties no longer regulated by APHIS. 

• APHIS assumes that most herbicide applications will conform to the EPA-registered uses 

for corn and soybean that are summarized in Appendix 7 and 8.

• In addition to corn and soybean, APHIS assumes that most other approved 2,4-D uses 

(e.g. on pastures, wheat, oats, barley, millet, rye, sorghum, rice, cotton, sugarcane, 

almonds, apples, apricots, cherries, citrus, hazelnuts, nectarines, peaches, pears, pecans, 

plums, walnuts) will conform to EPA-registration requirements. 

• APHIS assumes that drift from 2,4-D and other pesticide applications will be mitigated to 

an acceptable level by the registration requirements established by the EPA.

• APHIS assumes that all 2,4-D treatments made to EnlistTM corn and soybean will also 

include glyphosate because stewardship agreements between DAS and growers will 

stipulate that Enlist DuoTM products (which are a mixture of glyphosate and 2,4-D) be 

used. 

• Herbicide use estimates were made for 2,4-D, glyphosate, quizalofop, and glufosinate for 

the four alternatives and discussed in detail in Appendix 4. These estimates were based 

on the assumption that 2,4-D crop uses will increase, while 2,4-D uses on turf, range, 

pasture, and industrial management will not change. APHIS also acknowledges that the 

availability of dicamba resistant soybean varieties on the market is reasonably 

foreseeable. Dicamba and 2,4-D are both synthetic auxins with very similar herbicide 

chemistries. They are not likely to be used simultaneously because EnlistTM crops are 

sensitive to dicamba, dicamba resistant crops are sensitive to 2,4-D, and APHIS is not 

aware of any cross licensing agreements between Dow and Monsanto that would allow 

these traits to be stacked. When APHIS estimated the upper bound of 2,4-D use, it was 

assumed that all herbicide resistant corn (82 million acres) and 68% of the soybean acres 

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(52 million acres) would have the EnlistTM trait whereas 32% of the soybean acres would 

have an alternative herbicide resistance trait such as dicamba. Competition with soybean 

varieties resistant to herbicides such as dicamba, isoxaflutole, mesotrione, and glufosinate 

may reduce the assumed upper boundary to below 68% of the total soybean acres. In 

brief, 2,4-D use is expected to increase under the No Action and Action Alternatives. 

Under the No Action Alternative, 2,4-D use is expected to increase by 75% compared to 

current day use. Under the Action Alternatives, the increase in 2,4-D use is expected to 

be greater by up to 300 percent compared to the No Action Alternative. Glyphosate use 

on corn and soybean is not expected to increase under the No Action and Preferred 

Alternatives because of market saturation; i.e. as of 2011, 90 percent of the corn acres 

and 96 percent of the soybean acres are already treated with glyphosate. Quizalofop use 

is expected to decrease under the Preferred Alternative relative to the No Action 

Alternative because glyphosate still adequately controls grass weeds and the current use 

of quizalofop to control corn volunteers in soybean is likely to diminish with adoption of 

EnlistTM corn. Glufosinate use is expected to increase less under the Preferred Alternative 

relative to the No Action Alternative based on the expectation that 2,4-D is considered a 

more favorable option for GR weed control compared to glufosinate.

5.7 Preferred Alternative

5.7.1 Socioeconomic and Human Health Factors

Land Use

U.S. corn and soybean acreage increased over the past two decades. The greatest increase 

occurred in the northern and western parts of region G and the northeastern section of region I 

(USDA-NASS, 2013c). During the same period, wheat and small grain acreage decreased in 

these areas (USDA-NASS, 2013c).

Assuming USDA approval of the three petitions and EPA’s independent registration of Enlist

DuoTM both occur, corn and soybean acreage in regions A-M are not expected to change because 

other factors such as corn and soybean prices have a greater influence on planting decisions. 

Corn acreage is expected to decrease from 97 million acres to 88.5 million acres over the coming 

decade while soybean acreage is expected to expand from 76.5 million acres to 78 million acres

(USDA-OCE, 2014).

Domestic Uses of Corn and Soybean in the U.S.

The uses of corn and soybeans in commerce are described in the No Action Alternative. The 

Preferred Alternative is not likely to have cumulative impacts on the uses of corn or soybean 

because the influences on these uses are not related to weed control.

Corn and Soybean Agronomic Practices and Costs of Production

Tillage

Adoption of DAS-40278-9 corn, DAS-68416-4 soybean, or DAS-44406-6 soybean together with 

EPA approval of the Enlist DuoTM registration label may reverse a trend of increasing tillage that 

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is occurring now and expected to continue under the No Action Alternative. No-till cropping 

practices are based on effective herbicide weed control (APHIS-2013-0042-5139). Tillage 

increases are occurring in certain areas where herbicide-resistant weeds are no longer effectively 

controlled by currently-registered herbicides (see section 4.1.1. Tillage). Reports of increased 

tillage as a result of GR weeds have already been reported for cotton and soybean (Riar et al., 

2012; Shaw et al., 2012). In some Tennessee counties, the area devoted to conservation tillage 

was decreased by as much as 25 percent in soybean fields infested with GR horseweed (Shaw et 

al., 2012). Use of DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean are 

expected to improve the control of GR weeds and as a consequence, tillage is less likely to be 

needed for weed control under the Preferred Alternative. Therefore it is expected that less tillage

will occur in areas where GR weeds are widespread under the Preferred Alternative compared to 

the No Action Alternative. This potential reduction in tillage is most likely to occur with the use 

of DAS-68416-4 soybean and DAS-44406-6 soybean because the increase in the use of tillage 

for weed management is occurring in soybeans (Shaw et al., 2012) because corn growers have 

more herbicide options.

Crop Rotation

Adoption of DAS-40278-9 corn, DAS-68416-4 soybean, or DAS-44406-6 soybean is not 

expected to change corn and soybean crop rotation practices. However, if 2,4-D-resistant weeds 

become a problem that reduces the cost effectiveness of growing certain crops, this could change

crop rotation practices. For example, small grain crops are sometimes rotated with soybeans (see

Figure 10). Input costs are just one factor that determines whether a given rotation crop is grown. 

Other considerations include benefits to the soil, disease management considerations, and 

economic returns from growing the rotation crop. Some small grain cereals rely on 2,4-D for 

inexpensive weed control. If 2,4-D were to become ineffective and the cost of alternative

herbicides were too expensive, growers may choose not to grow small grains. 

Agronomic Inputs

Adoption of DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean is not 

expected to change corn and soybean production except to increase 2,4-D usage. Fertilizer, 

insecticide, fungicide, and water use are expected to remain unchanged from the No Action 

Alternative. Grower weed control costs are expected to be improved relative to the No Action 

Alternative. Many weed science experts submitted comments to the EIS docket with new 

information that supports this concept. 

From a Professor of Weed Science (APHIS 2013-0042-1911): “Neither dicamba nor 2,4-D are 

consistently effective in controlling Palmer amaranth larger than 4 inches when applied alone 

(Culpepper et al., 2011; Culpepper et al., 2010; Merchant et al., 2014), however, weed 

management systems including these herbicides are more consistently effective than current 

standards (Beckie, 2011; Braxton et al., 2010; Merchant et al., 2014; Richburg et al., 2012; 

Shaw & Arnold, 2002). Weed management programs, including 2,4-D or dicamba, would 

improve a grower’s ability to manage this problematic weed in the following ways: 1) improved 

consistency in weed control, especially on dryland production acres, where residual herbicides 

often are not activated with rainfall at planting time, 2) more flexibility with herbicide 

application timings because glufosinate plus dicamba or 2,4-D will consistently control Palmer 

amaranth up to 6 inches in height (at least 2 inches larger than today’s standards), 3) less 

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herbicide carryover to subsequent crops because growers would be less dependent on long 

lasting residual herbicides, and 4) less yield loss from Palmer amaranth crop competition for 

light, nutrients, and water (Coetzer et al., 2002; Culpepper et al., 2010; MacRae et al., 2013; 

Merchant et al., 2014)

From a state weed science extension specialist, (APHIS-2013-0042-5139) “complete weed 

control before planting helps ensure successful planting and crop emergence. We recommend a 

mixture of herbicide modes of action. One mode of action commonly used is exhibited in 2, 4-D 

because of its ability to control several difficult but competitive weeds. Unfortunately, current 

herbicide labels require planting delays of up to two weeks. Our agronomic research indicates 

that timely planting is one of the most effective ways to increase corn and soybean yields. 

Deregulation of Enlist traits will allow for timely planting. Timely planting will increase crop 

productively and allows for the establishment of a crop canopy earlier, and this helps protect the 

soil.”

“One final comment related to soil conservation. There has been renewed interest in the use of

cover crops in soybean and corn cropping systems. Cover crops reduce soil erosion in much the

same way as crop residue found in no-tillage. Plant leaves intercept raindrops and dissipate their

energy. In addition, roots slow water runoff and hold the soil in place. Plant species in the

legume family are popular inclusions in a cover crop mix – especially in corn cropping systems –

because of their ability to fix nitrogen. Glyphosate sometimes struggles with providing good

legume control. Addition of 2, 4-D to a burndown mix greatly increases cover crop kill, but label

restrictions may delay corn or soybean planting. Deregulation of Enlist traits will increase timely

corn planting and reduce early competition from cover crop plants.” (APHIS-2013-0042-5139).

Herbicides

Proximity of Corn and Soybean to Other 2,4-D Treated Crops

EnlistTM corn and soybean are expected to be attractive to those corn and soybean growers who 

have or will have difficulty with weed control caused by GR weeds. In the event that EnlistTM 

corn and soybean become widely used and 2,4-D-resistant weeds become more widespread, 

there are two types of growers that are most likely to be impacted. 

The first are the soybean and corn growers who almost exclusively have adopted GR crops and 

are already confronted with weed control problems related to GR weeds. Until now, these 

growers have relied more on glyphosate than 2,4-D, but are expected to adopt EnlistTM crops and 

develop a reliance on 2,4-D as a solution to the GR weed problem. The ease and effectiveness of 

2,4-D use may delay the need to adopt a more diversified weed management program for these 

growers. Several weed experts commented that for a number of reasons, growers are unlikely to 

over-rely on Enlist DuoTM the way farmers over- relied on glyphosate (APHIS 2013-0042-1911; 

3217; 8196); because Enlist DuoTM will not give the type of control that glyphosate alone gave. 

According to these experts, for weeds such as Palmer amaranth, growers will have no choice but 

to use additional residual herbicides through the season in order to get effective weed control. 

Because auxin herbicides only control Palmer amaranth less than 4 inches in height, they may 

tank mix Enlist DuoTM with glufosinate in order to control Palmer amaranth less than 6 inches in 

height. These experts predict that residual herbicides and/or glufosinate would need to be 

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included in weed programs managing GR weeds, and the additional herbicide chemistries would

likely delay the selection of 2,4-D resistant weeds. 

APHIS acknowledges these comments (APHIS 2013-0042-1911; 3217; 8196) and finds the 

argument compelling. Nevertheless, APHIS cannot rule out the possibility that some growers 

will over-rely on Enlist DuoTM, either because they are adequately controlling weeds that, unlike 

Palmer amaranth, are effectively controlled only by Enlist DuoTM or they do so for unforeseen 

circumstances. It is also possible that some growers may over-rely on synthetic auxins by 

rotating between EnlistTM crops and dicamba-resistant crops, selecting for weeds that may have 

cross resistance to these synthetic auxins, despite the availability of herbicide-resistant crops that 

have other sites of action such as glufosinate and HPPD inhibitors. In the event that 2,4-Dresistant weeds became prevalent in their region, these growers would have to become less 

reliant on 2,4-D and diversify their management programs in ways that would be similar to that 

described in the No Action Alternative.

The second type of grower that is most likely to be impacted are growers who already rely on 

2,4-D for weed control in applications that do not involve GR crops, growers of certain small 

grains being one example. These growers are more reliant on 2,4-D than glyphosate for weed 

control and may not currently be faced with the same degree of weed control problems as the 

first group. The development of 2,4-D resistant weeds resulting from reliance of the EnlistTM 

crop adopters on 2,4-D would render the herbicide less effective to those who were already using 

it on other crops. This could necessitate the need to adopt more costly and less environmentally 

beneficial weed management practices than are currently in use. One commenter thought that 

APHIS overstated the potential impacts from 2,4-D resistant weeds to grain growers who rely on 

2,4-D. His reasoning was that “common weeds in small grains and pastures are seldom the same 

species in corn and soybean, and vice versa.” (APHIS-2013-0042-3217). APHIS acknowledges 

this point, but it couldn’t rule out the possibility that this observation would no longer be 

representative if a weed shift occurred from high selection pressure resulting from 2,4-D use in 

corn, soybean, and wheat fields

No cumulative impacts are expected on organic growers because these growers do not use 

herbicides such as 2,4-D for weed control and HR weeds would not be harder to control by 

alternative measures. 

To analyze the potential impacts from increased selection for 2,4-D-resistant weeds under the 

Preferred Alternative, APHIS assumed that the greatest potential for impacts would be in regions 

where sizeable amounts of corn or soybean were grown in proximity to sizeable amounts of 

crops that already use 2,4-D for weed management. This impact is likely highest in crops grown 

in rotation with EnlistTM corn and soybean. The agricultural resource management survey 

conducted in 2011 reports on crop rotation patterns in major U.S. crops (Figure 10)(USDA-ERS, 

2011a). It shows that about 25 percent of corn is planted following corn, but most of corn is 

followed by soybeans, and an even higher percentage of soybeans are followed by corn 

(approximately 75 percent). About 10 to 20 percent of corn and soybean is rotated to other crops. 

About 10 percent of wheat is rotated to soybean and approximately 20 percent of cotton is 

rotated to other crops including corn and soybean. When moisture is adequate, growers in 

southern Indiana, Illinois, Missouri and Arkansas may double crop winter wheat and soybeans in 

the same year. This leads to rotation of much of the winter wheat in this area with soybeans. 

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However, there are no accurate ways of determining exactly what land is rotated from corn or 

soybean to other crops reliant on 2,4-D.

APHIS assumed that regional proximity of 2,4-D utilizing crops to corn and soybean would be 

the primary factor creating the potential for cumulative impacts from the selection of 2,4-Dresistant weeds in corn or soybean. Accordingly, APHIS identified areas where corn or soybean 

and crops to which 2,4-D is applied comprised the major crops in a given ecoregion. Table 4-7 

(Appendix 4), identifies the major crops onto which 2,4-D is applied. A crop was included in this 

category if 10 percent or more of the crop was treated with 2,4-D. Crops include: almonds, 

apples, apricots, barley, cherries, citrus, corn, cotton, hazelnuts, millet, nectarines, oats, peaches, 

pears, pecans, plums, rice, rye, sorghum, soybeans, sugarcane, walnuts, and wheat (US-EPA, 

2012a). From Table 6, APHIS obtained the percent of regional cropland devoted to the major 

crops of each ecoregion. These data are summarized in Table 10. 

Ecoregions A, B, C, E, and G are all areas where corn and soybean predominate and crops which 

receive applications of 2,4-D are minor components of the landscape. If 2,4-D resistant weeds 

become widely prevalent in these regions, few growers would be affected, though those who are 

may change their management practices. Similarly, in regions K, L, and M, EnlistTM corn and 

soybean are not expected to contribute to the cumulative impacts associated with the selection of 

2,4-D-resistant weeds because little corn and soybean is grown in these regions relative to the 

crops on which 2,4-D is applied. In contrast, ecoregions D, F, I, H, and J all represent areas 

where corn, soybean, and other crops onto which 2,4-D is applied are grown in abundance and in 

proximity (shaded in gray in Table 10). They offer the highest potential for cumulative impacts 

on small grain producers, who rely on 2,4-D for weed control, resulting from the selection of 2,4-

D resistant weeds in corn or soybean, that might occur due to the potential increased use of 2,4-D 

on EnlistTM corn and soybean.

Ecoregion D includes the coastal southeast. Principal crops that have 2,4-D applied in this region 

are wheat and cotton. 

Ecoregion F includes southern states bordering the Mississippi River (LA, MS, AR, TN, and 

MO). Principal crops that have 2,4-D applied in this region are wheat, cotton, rice, and 

sugarcane. Both ecoregions have a very high incidence of GR weeds, so the potential for 

selecting weeds with multiple resistance to glyphosate and 2,4-D is high relative to other 

ecoregions. The likelihood will depend on the extent to which growers rely exclusively on Enlist 

DuoTM versus employing a range of other management techniques. Because of losses recently 

experienced with GR weeds, growers may be more motivated to employ best management 

practices.

Ecoregion H includes parts of western North and South Dakota. The major crop that has 2,4-D 

applied in this region is wheat. Acreage for wheat in this region is approximately the same as that 

for corn and soybean. 

Ecoregion I consists of western KS, NE, eastern WY, eastern CO and parts of western TX and 

western OK. Major crops in the region that have 2,4-D applied are wheat, cotton, sorghum, and 

small grains.

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Ecoregion J consists of a part of central Texas. This region grows corn but no soybean. Crops 

that receive applications of 2,4-D include small grains, cotton, and sorghum. In both Ecoregion I 

and J, other crops receiving applications of 2,4-D exceed the amount of corn and soybean that is 

grown. Cumulative impacts are not expected in Ecoregion J under Alternative 4 (deregulation of 

soybean only) or in the case that EnlistTM corn is not widely adopted in this region.

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Table 10. Percent of Regional Cropland Devoted to Corn/Soybean or 2,4-D Utilizing Crops in Each EcoRegion

Percent of Regional Cropland

Region

Crops on which 2,4-D is utilized Total Total

Corn Soy Wheat

Oat, 

Barley, 

Millet Cotton Rice Sorghum Sugarcane

Nut 

and 

Fruit 

Trees

% of 

Cropland 

in Corn 

+ Soy

% of 

Cropland 

in Other 

Crops 

Using 

2,4-D

A 51 20 3 2 71 5

B 51 25 4 76 4

C 53 40 3 93 3

D 33 33 15 18 2 66 35

E 52 46 7 1 98 8

F 51 20 10 12 11 1 71 34

`G 45 40 8 85 8

H 23 14 40 37 40

I 28 11 38 1 12 8 39 59

J 26 0 38 7 8 18 26 71

K 13 0 26 6 48 6 13 86

L 12 0 20 14 12 34

M 10 11 25 10 35

Regions shaded in gray indicate areas where corn or soybean are major crops and other 2,4-D utilizing crops are also 

widely prevalent.

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Weed Control, Herbicide Alternatives and 2,4-D Use in Non-GE Crops

To evaluate how crops that currently use 2,4-D for weed control might be impacted if 2,4-Dresistant weeds become more prevalent, APHIS examined the management options and costs for 

weed control in these crops. Weed control programs vary by crop, weed problem, geography, 

and cropping system (e.g. no-till, conventional-till, etc.). In those crops where it is labeled for 

use, 2,4-D is usually just one part of a much broader weed management strategy. Many growers 

use a combination of weed control techniques including cultural, mechanical, and chemical. 

From the EPA Screening Level Estimates of Agricultural Uses of 2,4-D (US-EPA, 2012a), 

APHIS identified 23 crops where as much as 10 percent of the crop is treated with 2,4-D (Table 

4-7). Many of these, (e.g., tree crops) are managed similarly and are considered together. For 

each crop, or group of similar crops, APHIS considered the types and cost of herbicides that are 

used for broadleaf weed control. APHIS focused on post-emergence, broadleaf weed control as

this is the primary use of 2,4-D in these crops.

Pasture

The largest agricultural use of 2,4-D is for pastures (Texas Cooperative Extension). An estimated 

10.6 million pounds of active ingredient (ai) are used annually to treat pastures.

Alternative Herbicides and Management Options

Effective management of weeds in pasture and rangeland usually involves a combination of 

cultural, mechanical, and chemical methods. The primary means of controlling weeds is proper 

management of desirable forage grasses and legumes. Overgrazing is a major cause contributing 

to the establishment and proliferation of weeds. Low soil fertility in pastures also contributes to 

weed problems. Some degraded pastures can be revitalized by reseeding or inter-seeding to 

improve forage growth and competition. For some situations, burning or mowing can stimulate 

forage grass growth and suppress weeds. Combined with well-timed herbicide applications, these 

methods can effectively manage weeds (DAS, 2013b).

Other methods that have a definite place in range management are: chemical, roto-beating, 

plowing, disking, railing, chaining, burning, reseeding, and changes in grazing schedules. There 

are specific sites and reasons for use of the controls listed. Each is effective if used properly

(DAS, 2013b).

Table 11 shows a range of herbicide products that are currently registered for pastures and 

rangeland and their estimated costs. Herbicide alternatives to 2,4-D that provide reasonable lowcost herbicide control are shaded in gray. Most pasture is not treated with herbicide. Mowing is a 

non-chemical control method that is often used and is estimated to cost $13.95/acre in NE 

(University of Nebraska-Lincoln). (DAS, 2013b).

Table 11. Post-emergence Broadleaf Herbicides Commonly Used in Pastures and 

Rangeland

Herbicide

(common name)

SOA1 Rate

(lb ae or ai/A)

$/Acre

2,4-D 4 1-2 5.00-10.00

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Herbicide

(common name)

SOA1 Rate

(lb ae or ai/A)

$/Acre

Aminopyralid 4 0.06-0.11 16.12-32.11

Metsulfuron 2 0.06-0.6 1.35-13.53

Carfentrazone 14 0.015-0.031 1.70-3.40

Chlorsulfuron 2 0.19-1.0 5.00-25.08

Clopyralid 4 0.14-0.375 13.33-35.70

Dicamba 4 0.5-1.5 9.99-29.97

Fluroxypyr 4 0.6-0.72 20.63-24.76

Picloram 4 0.25 7.50

Triclopyr 4 0.25 3.75

Hexazinone 5 0.67-1.12 25.54-42.69

Paraquat 22 0.25-0.5 3.98-7.96

Tebuthiuron 7 0.4 16.00

Source: (DAS, 2013b; Texas Cooperative Extension)

1

Weed Science Society of America site of action category

Alternative low cost herbicide options to 2,4-D are shaded.

Potential Impacts to Pasture from Increased Weed Resistance

Although pasture represents the largest agricultural use of 2,4-D receiving 10,600,000 pounds of 

active ingredient, just 10-15 percent of the pasture is treated with 2,4-D (US-EPA, 2012a). Nonchemical options are most often used, and there are similarly priced chemical alternatives to 2,4-

D. Thus, even if 2,4-D-resistant weeds became more prevalent, the increased costs to manage 

such weeds in pasture are expected to be small under all the alternatives.

Small Grains (Wheat, Barley, Oats.)

An average of 30 percent and up to a maximum of 65 percent of the wheat crop is treated with 

2,4-D (US-EPA, 2012a) and it may be rotated with corn or soybeans. In some areas such as 

Indiana, Illinois, Kentucky, Missouri, and Arkansas, winter wheat is often planted with the intent 

to double crop with soybeans the same season. Winter wheat is harvested (usually in June) and 

soybeans are planted in no-till wheat stubble, when there are favorable moisture conditions

(Moechnig & Wrage, 2012; North Dakota State University). 

An average of 25 percent and up to a maximum of 40 percent of the barley and an average of 15 

percent or maximum of 20 percent of the oat crop is treated with 2,4-D (US-EPA, 2012a). Crop 

rotation is a recommended weed management practice, providing a tangible, recognized level of 

control where practiced. Conditions are usually very favorable to winter wheat growth in the fall, 

and the crop out-competes many weeds. Only 40 to 50 percent of the winter wheat receives any 

herbicide application in these states. 

Alternative Herbicides and Management Options

A wide range of herbicide products are currently registered for small grains. Use of pre-plant or 

pre-emergence herbicides occurs on a small portion of grain acreage usually with 1-2 postemergence applications. Post-emergence graminicides are often used to control grass weeds such 

as wild oats and foxtail. Many different herbicides are available for post-emergence broadleaf 

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weed control. Dominant modes of action in small grains are auxins (WSSA Group 4) and ALS 

inhibitors (WSSA Group 2). While 2,4-D is a widely used herbicide for these crops, it does not 

provide acceptable control of some key broadleaf weeds such as kochia and wild buckwheat. 

Therefore, 2,4-D treatments are often combined with one of the herbicides listed in Table 12

(DAS, 2013b). 

In low-production areas (e.g., the far western and southern U.S. plains) 2,4-D is sometimes used 

individually (DAS, 2013b).

Table 12 (DAS, 2013b) lists a number of alternative herbicides and estimated costs. Metsulfuron, 

an ALS inhibitor for example, can provide control similar to 2,4-D at low cost; however,

resistance to ALS inhibitors are widespread. The cost of some other products, such as a premix 

of pyrosulfotole and bromoxynil, is higher than 2,4-D, but this combination also provides high 

levels of control of some key broadleaves, such as kochia and wild buckwheat, that 2,4-D does 

not control (DAS, 2013b).

Some non-chemical control methods can also substitute for 2,4-D or enhance other control 

measures. Weeds such as common lambsquarters and common ragweed often germinate early in 

the spring. Tillage just before spring planting can eliminate the major flush of these early 

emerging weeds. A 2009 USDA report on custom tillage rates estimated the cost of harrowing at 

$7.30-8.40 per acre in Kansas (DAS, 2013b). 

Table 12. Post-emergence Broadleaf Herbicides Currently Available for Use in Wheat, 

Barley, Oats, and Rye

Herbicide

(common 

name)

SOA1 Crops2 Application 

Rate

(lb. ae or 

ai/A)

Cost

($/Acre)

Comments

2,4-D amine 4 WW, SW, 

B, O, R

0.25-0.5 1.15-2.30

MCPA 4 WW, SW, 

B, O, R

0.25-0.5 1.30-3.20 Similar in spectrum to 2,4-D

Bromoxynil 6 WW, SW, 

B, O, R

0.25-0.5 8.80-19.05

Carfentrazone 14 WW, SW,

B, O, R

0.008-0.031 4.00-15.10

Chlorsulfuron 2 WW, SW, 

B, O

0.008-0.015 3.60-7.05

Clopyralid 4 WW, SW, 

B, O

0.09-0.12 16.80-22.15

Dicamba 4 WW, SW, 

B, O, R

0.06-0.12 2.30-5.25

Pyrasulfotole 27 WW, SW, 

B, O

0.028-0.038 8.50-11.55 Available only in premix w/ 

bromoxynil

Florasulam 2 WW, SW, 

B, O

0.004 7.20 Available only in premix w/ 

MCPA

Fluroxypyr 4 WW, SW, 

B, O

0.11-0.14 10.60-14.15

Thifensulfuron 2 WW, SW, 

B, O

0.014-0.019 15.95-31.85

Tribenuron 2 WW, SW, B 0.008-0.16 4.70-9.35

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Herbicide

(common 

name)

SOA1 Crops2 Application 

Rate

(lb. ae or 

ai/A)

Cost

($/Acre)

Comments

Metsulfuron 2 WW, SW, B 0.004 1.50

Prosulfuron 2 WW, SW, 

B, O

0.009-0.018 3.65-7.25

Pyraflufen 14 WW, SW, 

B, O, R

0.0008-0.0016 1.65-3.30 Primarily pre-plant but can be 

applied POST

Triasulfuron 2 WW, SW 0.013-0.026 3.00-6.05

Imazamox 2 WW, SW 0.031-0.047 16.25-24.40 Clearfield varieties only 1

Weed Science Society of America site of action category

Alternative low cost herbicide options to 2,4-D are shaded.

Abbreviations:

B=barley; O=oats; SW=spring wheat; R=rye; WW=winter wheat 

Source: (DAS, 2013b).

Potential Impacts of 2,4-D-Resistance on Small Grains

Winter wheat, spring wheat, barley, and oat growers often do not use herbicides. When needed, 

2,4-D provides an inexpensive and effective weed management tool. As noted in the discussion 

that follows, there are several areas where these crops are rotated with either corn or soybean or 

grown in proximity. If 2,4-D-resistant weeds were to develop in corn and soybean fields, it is 

likely that they could eventually be found in wheat and small grain rotation crops on neighboring 

farms. Most likely, alternative chemical control options would be more expensive. MCPA (2-

methyl-4-chlorophenoxyacetic acid) is similarly priced but also has a similar mode of action to 

2,4-D, so weeds resistant to 2,4-D may also be resistant to MCPA. Other low cost herbicides, 

such as the ALS inhibitor metsulfuron, may not be as effective because of widespread resistance 

to ALS inhibitors. Pyraflufen is a low-cost PPO inhibitor that is usually used pre-plant. It cannot 

be used post-emergent (unlike 2,4-D) on small grains except wheat, and it has more restrictions 

than 2,4-D when used on wheat. Thus, chemical alternatives to 2,4-D are less flexible and more 

costly. This indicates that there would be cumulative impacts to wheat and small grain growers if 

2,4-D-resistant weeds become more prevalent. 

Fallow and Burndown Uses 

For many crops, including corn and soybean, 2,4-D is often used in mixes with other herbicides 

such as glyphosate, glufosinate, or paraquat in the spring and fall prior to planting. This timing, 

usually referred to as “burndown,” can run anywhere from 0-30 days prior to planting, depending 

on the crop, geography, and product used. It is used to improve control of winter annuals, 

perennials, and early-emerging, summer annual weeds. Examples of weeds controlled include 

shepardspurse, marestail, dandelion, common lambsquarters, and giant ragweed. Often this is a 

critical part of an overall weed control program since it removes weeds that will be competing 

with the crop as it emerges. Burndown herbicide applications are almost obligatory for no-till 

crop production systems where tillage is not desired. Use of no-till crop culture is common in 

corn, soybeans, cotton, and wheat. Both soybeans and cotton are largely planted as GR varieties 

and glyphosate is an important herbicide used in post-emergent weed control. For wheat 

managed with herbicides, burndown applications are popular because there are few postemergent options (DAS, 2013b).

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Fallowing (i.e., leaving land unplanted) is used in arid areas of the plains and the West as a 

means to store soil moisture for a following crop. Fallow may encompass the summer season but 

is usually applied to a longer period of time (often 4-12 months). Weed control on fallowed acres 

is critical for reducing moisture loss. While tillage is an alternative to herbicidal control, it is 

usually less desirable because it increases erosion, costs of fuel and labor, and soil moisture loss

(DAS, 2013b).

Alternatives to 2,4-D

Herbicides effective for burndown and foliar activity on broadleaf weeds are listed in Table 13. 

Depending on the crop to be planted and the target weed species, these products can offer an 

alternative to 2,4-D, but at greater cost. In several cases, these herbicides offer some advantages 

over 2,4-D such as longer residual control(DAS, 2013b). 

Additionally, some non-chemical control methods can substitute for 2,4-D or enhance other 

control measures. Tillage can substitute for herbicide applications to remove weeds before 

planting, except where no-till conditions are desired (DAS, 2013b). Using a price for diesel of 

$3.50/gal, the fuel cost for tillage ranges from $19-25/acre using the USDA energy estimator for 

tillage in IA, NC, and AR (USDA-NRCS, 2013).

Table 13. Fallow and Burndown Herbicides Available for Use on Selected Crops

Herbicide

(common 

name)

SOA1 Crops2 Rate

(lb ae or ai/A)

Cost 

($/Acre)

Comments

2,4-D amine 4 C, SB, CT, SG 0.25-0.5 1.15-2.30

Atrazine 5 C 1.0 3.20

Isoxaflutole 6 C 0.05-0.09 14.90-29.80

Chlorimuron 14 SB 0.033 8.10 Usually in combination with 

metribuzin ($18/A)

Metribuzin 5 C, SB 0.5-0.75 5.60-8.50 Often at lower rates in 

combination w/ other 

herbicides

Dicamba 4 C, SB, CT,SG 0.25 5.25

Mesotrione 28 C 0.18-0.24 32.00-41.00

Glyphosate 9 C, SB, CT, SG 1.0-1.5 4.00-6.00

Flumioxazin 14 CT, SB 0.05-0.1 9.00-18.00

Sulfentrazone 14 SB 0.14-0.375 23.60-63.00 Obtained at lower cost in 

premixes

Saflufenacil 14 C, SB, SG .02 5.45

Paraquat 22 C, SB, CT, SG 0.5-1.0 9.00-18.00

Glufosinate 10 C, CT, SB 0.53-0.66 13.60-16.85

Iodosulfuron 2 C, SB 0.0019 7.20 Fall only for soybeans, up to 

30 d before corn 1

WSSA site of action category 2

C=corn, SB=soybean, CT=cotton, SG=small grain

Alternative low cost herbicide options to 2,4-D are shaded.

Source: (DAS, 2013b).

Potential Impacts of 2,4-D-Resistant Weeds on Fallow and Burndown Applications

Development of weed resistance to 2,4-D would impact fallow and burndown applications 

because 2,4-D complements the effectiveness of glyphosate. Some important weeds controlled 

by 2,4-D are resistant to glyphosate (e.g., marestail and giant ragweed). Others (e.g., 

lambsquarters) have always been tolerant of glyphosate and are more effectively controlled by 

129
2,4-D. Other herbicides are available for these applications, but are more costly. Therefore, loss 

of 2,4-D as an effective herbicide would increase management costs. Crops that would be 

adversely impacted include cotton, soybean, corn, and wheat. 

Sorghum 

Sorghum is most commonly rotated with wheat, corn, and soybean (Bean & Trostle, 2013). In 

Texas, sorghum is also rotated with cotton, and sometimes peanuts.

A number of herbicide products are currently labeled for sorghum. Herbicide management for 

sorghum can include burndown, pre-emergence, and post-emergence herbicide applications. Preemergence applications typically use atrazine in combination with an acetamide such as 

metolachlor. Post-emergence herbicides such as 2,4-D, atrazine, dicamba, bentazon, and 

bromoxynil are used to control broadleaf weeds that escape the pre-emergence treatment. These 

herbicides may be combined in premixes or tank mixes to broaden the weed control spectrum. 

Common combinations include 2,4-D with atrazine, dicamba with atrazine, and bromoxynil with 

atrazine (DAS, 2013b). 

In-season row cultivation has been used in the past to control weeds, but it is less commonly 

used today because it requires costly fuel and labor expenses (DAS, 2013b).

Alternative Herbicides and Management Options

Several possible alternative herbicides for weed control in sorghum and their estimated costs are 

summarized in Table 14. Atrazine, for example, provides control equivalent to 2,4-D on most 

weeds and is similar in cost (DAS, 2013b). 

Some non-chemical control methods can also substitute for 2,4-D or enhance other control 

measures. Weeds such as common lambsquarters and common ragweed often germinate early in 

the spring. Tillage just before planting can eliminate these early emerging weeds. A 2009 USDA 

report on custom tillage rates estimated the cost of harrowing at $7.30-8.40 per acre in Kansas.

In season row cultivation provides another, non-chemical alternative and costs between $7.00 

and $8.00 per acre (DAS, 2013b).

Table 14. Post-emergence Broadleaf Herbicides Currently Available for Use on Sorghum

Herbicide

(common name)

SOA§ Rate

(lb ae or ai/A)

Cost ($/Acre) Comments

2,4-D amine 4 0.25-0.5 1.15-2.30

Atrazine 5 1.0 3.20

Bromoxynil 6 0.25-0.5 8.80-19.05

Carfentrazone 14 0.008 4.00

Bentazon 6 0.5-1.0 12.60-25.20 Not a recommended tank mix on 

label but not prohibited

Dicamba 4 0.25 5.25

Prosulfuron 2 0.009-0.018 3.30-6.60

Halosulfuron 2 0.03 12.50

*Alternative low cost herbicides to 2,4-D are shaded. §

WSSA site of action category.

Source: (DAS, 2013b).

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Potential Impacts of 2,4-D-Resistant Weeds on Sorghum

If 2,4-D resistant weeds were to become a problem, sorghum growers would likely be impacted. 

2,4-D and dicamba are often applied with other herbicides such as carfentrazone (a PPO 

inhibitor) for more rapid activity to improve control. Weeds that 2,4-D effectively controls, such 

as ragweed, pigweed, and lambsquarters, already have atrazine and ALS resistant biotypes. 

Therefore, if 2,4-D-resistant weeds become a problem, weed management costs for sorghum 

would likely increase. 

Rice 

Rotating rice with corn/soybean is limited to the Mississippi River Valley and Texas (Louisiana 

State University Research and Extension, 2013; University of Arkansas, 2013).

Effective weed control in rice involves cultural, mechanical and chemical methods. A soybeansoybean-rice rotation is recommended rather than a soybean-rice rotation to allow management 

of grass weeds in the soybean crops. This reduces the number of grass weeds that emerge with 

the rice crop. A unique feature of rice culture is fields are permanently flooded after plants reach

6-8 inches. The primary purpose is weed control. Most grass and broadleaf weeds will not 

germinate after flooding. Therefore, early season weed control prior to flooding is critical for rice 

production. Control of grass weed species (e.g., barnyardgrass, watergrass, jungle rice, 

sprangletop species and red rice), is critical early in the growing season. None of these species 

are controlled by 2,4-D. Broadleaf weeds (e.g., dayflower, hemp sesbania, jointvetch, smartweed 

and morning glory species), can be controlled before or after flooding without yield or quality 

loss (DAS, 2013b).

Aquatic and broadleaf weeds that are not controlled prior to flooding can be controlled with a 

combination of herbicides (e.g., bispyribac, fenoxyprop, cyhalofop, penoxsulam, 2,4-D, or 

triclopyr) (DAS, 2013b).

Alternative Herbicides and Management Options 

When considering the potential for 2,4-D resistant weeds to move from corn or soybean 

production to rice production, the broadleaf weeds of concern will be those that can survive in 

the flooded rice culture. They include those typically listed as troublesome in rice. They include 

hemp sesbania, northern jointvetch, morning glory, smartweed, dayflower, ammania species and 

the aquatic weeds, alligator weed and ducksalad. Table 15 lists several possible herbicide 

alternatives to 2,4-D and their estimated costs. Alternative herbicides cost more than 2,4-D, but 

are currently used because they provide better control of a broader spectrum of broadleaf weeds 

and grasses. Another advantage of the alternative broadleaf herbicide products is that they are 

effective for a longer period than 2,4-D.

Table 15. Post-emergence Broadleaf Herbicides Currently Available for Use in Rice 

Production

Herbicide

(common name)

SOA§ Rate

(lb ae or ai/A)

Cost

($/Acre)

Comments

2,4-D 4 1.25-1.5 5.75-7.00

Acifluorifen 14 0.125 6.25

Bensulfuron 2 0.0375-0.0625 15.75-26.25

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Herbicide

(common name)

SOA§ Rate

(lb ae or ai/A)

Cost

($/Acre)

Comments

Bentazon 0.75-1.0 18.00-25.00

Bispyribac 2 0.32-0.63 41.00-81.00

Carfentrazone 14 0.025-0.05 12.00-24.00

Halosulfuron 2 0.023-0.063 12.50-33.75

Imazosulfuron 2 0.15-0.3 21.00-42.00

Penoxsulam 2 0.032-0.036 21.00-23.75

Propanil 3.0-6.0 17.50-35.00

orthosulfamuron 2 0.053-0.065 12.25-15.00

Triclopyr 4 0.375 11.00

quinclorac 4 0.375-0.5 20.00-26.75

Imazamox 2 0.031-0.047 14.00-21.25 Clearfield varieties only

Imazethapyr 2 0.063-0.094 14.25-21.25 Clearfield varieties only

*Alternative low cost herbicide options to 2,4-D are shaded

§

WSSA mode of action category

Source(DAS, 2013b).

Potential Impacts to Rice Growers from 2,4-D-Resistant Weeds

Rice growers rely heavily on flooding and herbicides other than 2,4-D for weed control. In 

several rice growing areas in Arkansas, statutory restrictions limit 2,4-D use (See Appendix 7). 

Because of the wide range of herbicides and non-chemical methods used for weed control and 

restrictions on 2,4-D use in some rice-growing areas, the impacts to rice growers in the event of 

selection and spread of 2,4-D resistant weeds is expected to be minor.

Cotton

Cotton is infrequently rotated with other crops (Figure 10). In Texas for example, few other 

crops are productive in the conditions of low rainfall and high heat favorable for cotton 

cultivation. In drought years, cotton may be abandoned on over 30 percent of these Texas acres.

Only in the mid-south is there an exception to this generalization. There, cotton may be rotated

with soybeans or corn (University of Georgia).

Weed Management Programs and Options

Cotton is an annual crop that is usually planted in wide rows (38-40 inches apart). Use of no-till 

crop culture is common in cotton and herbicides are an important means of weed control. 

Currently, most cotton varieties in the U.S. are GR, so glyphosate is the primary herbicide used. 

Common practice is a pre-plant or pre-emergence, soil-residual herbicide application followed 

by 1-2 post-emergence treatments usually with glyphosate. The soil-residual herbicides include a 

range of modes of action. Although a large portion of cotton acreage was once treated only postemergence with glyphosate, this practice is declining because GR weeds are now widely

prevalent in cotton fields. Glufosinate-resistant varieties are increasingly being used, so postemergent glufosinate applications are replacing glyphosate. Growers will sometimes apply 

herbicides such as pyrithiobac to control broadleaf weeds not controlled with glyphosate or postemergence graminicides such as clethodim or quizalofop to control grasses. Because cotton is 

naturally sensitive to 2,4-D and other auxin herbicides, the current use of 2,4-D for this crop is 

limited to pre-plant burndown uses. 2,4-D is usually added to burndown applications to improve 

control of winter annuals, perennials, and early emerging summer annual weeds. Burndown 

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occurs 0-30 days prior to planting depending on crop, geography, and product used. Burndown 

herbicide applications are almost obligatory for no-till crop production systems (DAS, 2013b).

2,4-D is typically used in combination with other broad-spectrum herbicides, such as glyphosate, 

glufosinate or paraquat. Herbicides with utility in burndown and significant foliar activity on 

broadleaf weeds are listed in Table 13. These herbicides are alternatives to 2,4-D. 

Some non-chemical control methods can also substitute for 2,4-D or enhance other control 

measures. Tillage can substitute for herbicide applications to remove weeds before planting 

except where no-till conditions are desired. USDA reports on custom tillage rates estimated the 

cost of most pre-plant tillage at $13-15 per acre.

Potential Impacts to Cotton Growers from 2,4-D-Resistant Weeds 

According to EPA estimates, only an average of 10 percent of cotton is treated with 2,4-D (USEPA, 2012a). 2,4-D use in cotton is limited to pre-plant burndown since cotton is sensitive to the 

herbicide. However, because of the widespread adoption of no-till in cotton production combined 

with the prevalence of GR weeds in cotton fields, 2,4-D is an important herbicide for burndown 

applications in cotton. Consequently, if 2,4-D resistant weeds become more prevalent, weed 

management costs will likely increase for cotton producers. 

Socioeconomic Impacts from Off-target Pesticide Movement

Spray Drift: An assumption in the No Action Alternative is that 2,4-D use will be applied to 30

percent of corn and soybean cropland based on the second assumption that GR weeds will 

increase from 10 to 30 percent of corn and soybean cropland. The first assumption is based on 

the observation that 2,4-D use in burndown applications is proving beneficial to control GR 

weeds such as horsetail and ragweed that emerge by spring and that 2,4-D use on corn and 

soybean has been steadily increasing (see Appendix 4). Current use of 2,4-D for burndown 

applications in corn and soybean are 10 percent and 12 percent, respectively. The 2,4-D 

formulation used under the No Action Alternative is expected to be dimethylamine (DMA) or 

ester formulations which are those currently used. The ester formulation is about 10 times more 

volatile than for DMA. No additional stewardship agreements are expected to occur to mitigate 

potential off-target movement of 2,4-D under the No Action Alternative. It is possible that the 

choline formulation will be available under the No Action Alternative if EPA approves EnlistDuoTM but APHIS does not grant nonregulated status to the EnlistTM crops. In that case, the 

choline formulation might be used on non-EnlistTM crops by growers committed to reducing off 

target pesticide movement. There would not be stewardship agreements requiring growers to use 

the choline formulation but growers might choose to use this formulation if Enlist DuoTM is 

competitively priced.

Under the Preferred Alternative, 2,4-D use on crops would increase 1.75-3 times more than that 

estimated under the No Action Alternative (see Appendix 4). Unlike the No Action Alternative, 

the formulation used for the incremental increase in 2,4-D use is expected to be the choline 

(Enlist DuoTM) formulation. This formulation is 50 times less volatile than DMA and 500 times 

less volatile than ester formulations (see Appendix 7). An independent trial by the University of 

Georgia extension has corroborated the conclusion that off-target movement is less likely with 

choline formulations compared to the ester and dimethylamine formulations (APHIS-2013-0042-

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1911-A2). The expected increase in 2,4-D use under the Preferred Alternative is not likely to 

result in more off-target effects because under the Preferred Alternative it will be applied as the 

choline formulation. This formulation is also likely to replace some current uses of the DMA and 

ester formulations, so the overall use of volatile formulations are expected to be less under the 

Preferred Alternative than under the No Action Alternative.

Though off-target pesticide movement is expected to be lower for the Preferred Alternative than 

for the No Action Alternative, the use of 2,4-D may occur over a longer season under the 

Preferred Alternative. This could increase exposure of sensitive plants to 2,4-D later in the 

season. These offsetting impacts (less volatile formulations and potentially greater exposure) 

make it difficult to predict which Alternative poses the greatest risk from drift damage. 

5.7.2 Biological Resources

Animal Communities

As described in the No Action Alternative, agricultural practices can affect wildlife in and 

around agricultural fields. Wildlife commonly found in each region is described in the Affected 

Environment, Section 3. As discussed in Section 4, DAS-40278-9 corn, DAS-68416-4 soybean, 

and DAS-44406-6 soybean will not directly or indirectly impact wildlife differently from the 

corn and soybean varieties that are currently available under the No Action Alternative. While 

direct impacts from the changes in herbicide use associated with Enlist DuoTM could affect 

certain wildlife, they are outside the scope of this EIS.

EPA considers impacts on wildlife as part of its evaluation of the amended label. 2,4-D has an 

extensive history of safe and effective use. It has been thoroughly reviewed and reregistered by

all major regulatory agencies in the world within the last ten years. In 2012, the EPA denied a 

petition to cancel tolerances and registrations for 2,4-D based on toxicological hazard (US-EPA, 

2012c). The Agency affirmed that 2,4-D posed no unreasonable risk when used as directed. 

Therefore, cumulative impacts on animal resources are not expected to differ between the No 

Action and Action Alternatives. 

Plant Communities

APHIS estimates of herbicide use under the four alternatives are listed in Table 4-14 of

Appendix 4. An increase in herbicide use is expected under all four alternatives. 2,4-D use on 

crops is expected to increase under the No Action Alternative from 25.6 million pounds in 2011 

to 44.5 million pounds by 2020. Under the Preferred Alternative, the increase is expected to 

range from 77.8-176 million pounds, depending on grower adoption rates. The increased use of 

herbicides under both the No Action and Action Alternatives is expected to result in increased 

selection pressure for 2,4-D-resistant weeds. 

Selection pressure is influenced by factors other than the volume of herbicide applied. The 

selection pressure is strongly related to the repeated use of one or a limited number of herbicides 

(Duke, 2005; Durgan & Gunsolus, 2003). It is also a function of the diversity of management 

practices employed. The greater the diversity of management practices, the smaller the selection 

pressure for resistant weeds. 

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All management techniques, including the use of herbicides, hand weeding, mowing, etc., exert 

pressure to select weeds to resist that management technique. For hand weeding, plants are 

selected that resemble the crop. For example, spurred anoda and nightshade resemble young 

cotton so these weeds are often overlooked during hand-weeding (Coble, 2012; University of 

California Davis, 1996). Mowing selects plants that flower rapidly and grow low to the ground 

(Radosevich et al., 2007). Mowing alters the stature of some weeds. Repeated mowing can 

change the appearance of a weed from a single-stemmed, tall, upright form to a plant with 

multiple shoots that are relatively prostrate. (Radosevich et al., 2007). Herbicides select for 

plants that are no longer sensitive to its site of action (Owen, 2008). 

The increased selection pressure resulting from the wide-spread use of glyphosate on GR crops, 

the subsequent reductions in the use of other herbicides, and changes in weed management 

practices (such as the reduction in tillage and decreased use of crop rotation), has resulted in both 

weed population shifts and increasing glyphosate resistance among some weed populations 

(Duke & Powles, 2009; Owen, 2008). GR crops themselves do not influence weeds any more 

than non-transgenic crops. It is the weed control tactics chosen by growers that create selection 

pressure that gradually shifts these weed communities and may result in the evolution of HR

weeds (Owen, 2008).

Herbicide-Resistant Weeds

In this section, the likelihood that problem weeds in corn and soybean, (i.e., those weeds that are 

actively managed in these crops), will become more resistant to 2,4-D is reviewed. Appendix 5

includes an analysis of the problem weeds of corn and soybean and those that have HR biotypes

are described in Appendix 6.

As of March 21, 2013, worldwide, there were 397 instances of HR weeds in 217 species (Heap, 

2013b). The first HR biotypes were described in the 1950s. The number of weeds resistant to 

herbicides increased dramatically in the 1980s and 1990s. Today, resistance to 21 of the 25 

known herbicide sites of action has been identified (Heap, 2013a). Of the 25 known herbicide 

sites of action, 11 are commonly used on corn and soybean (Appendix 4). Furthermore, while 

there are hundreds of cases of HR weeds, most of these weeds are not actively managed in corn 

and soybean. The analysis below focuses on weeds that are actively managed in corn and 

soybean fields and addresses which of these have developed herbicide resistance to the major 

herbicides used in corn and soybean.

There are 25 broadleaf and 22 grass weed species that require control measures in the major 

growing regions of soybean and corn (Appendix 5). There are 13 broadleaf and nine grass 

weeds, respectively, that are a problem in both corn and soybean, four broadleaf and seven grass 

weeds that are mostly problematic in corn (highlighted in yellow in Table 5-2 in Appendix 5), 

and eight broadleaf and six grass weeds that are mostly problematic in soybean (highlighted in 

blue in Table 5-2 in Appendix 5). 

The most common types of weed resistance in the U.S. are to ALS and Photosystem II

herbicides. There are 15 problem weed biotypes resistant to each mode of action. The problem 

weed resistant to the most sites of action is waterhemp. It is resistant to six of the eleven sites of 

action of herbicides commonly used in corn and soybean (Table 6-3 in Appendix 6). Multiple 

resistance involving biotypes with 13 combinations of sites of action have been reported, 

135
including one biotype that is resistant to five sites of action (Owen, 2012). Ragweed, kochia, and 

horseweed are each reported to have biotypes resistant to four sites of action including biotypes 

that are multiply resistant to two herbicides (Table 6-3 in Appendix 6). Multiple HR biotypes 

have also been selected in redroot pigweed and giant ragweed. None of the problem grasses have 

multiple resistances. A total of seven of the 47 problem weeds in corn and soybean include 

biotypes resistant to more than one herbicide (Table 6-3, Appendix 6).

To combat this trend and to avoid decreased crop yields resulting from weed competition, 

growers must continually adapt weed management strategies. Appropriate weed management 

requires much more than the application of herbicides. Rotation of herbicides with alternative

sites of action is one method (DAS, 2010a). Some common sites of herbicide action include

auxin growth regulators, amino acid inhibitors, chlorophyll pigment inhibitors, and lipid 

biosynthesis inhibitors (Ross & Childs, 2011) (Appendix 3). The practice of using herbicides 

with alternative sites of action could potentially diminish the populations of GR weeds and 

reduce the likelihood of the development of new HR weed populations (DAS, 2010a; Dill et al., 

2008; Duke & Powles, 2008; 2009; Owen, 2008).

Managing Glyphosate-Resistant Weeds

In 2012, the area of U.S. cropland infested with GR weeds expanded to 61 million acres, 

according to a survey conducted by Stratus Agri-Marketing (Farm Industry News, 2013). Table 

6-3 in Appendix 6 lists those weed species that have been identified as HR in at least some part 

of their range in the U.S. and internationally. The use of glyphosate on corn and soybean is not 

expected to increase under any of the Alternatives because most corn and soybean in the U.S.

already has the GR trait and so glyphosate use is saturated on these crops and the increase of GR

weeds only makes glyphosate use less attractive. To manage glyphosate resistance, growers are 

not using more glyphosate but are using more sites of action in addition to glyphosate. In the 

southeast, where GR weeds are particularly problematic, there is a decline in glyphosate use on 

soybean (Appendix 4, Figure 4-3).

Southeastern soybean growers who have adopted no-till production are now including 

increasingly aggressive tillage in their management programs. They are also applying herbicides 

with different modes of action, and adopting other stewardship practices that reflect the 

recommendations for BMPs as outlined by the Weed Science Society of America and the 

National Science Foundation (Ferrell, 2013; WSSA, 2010). In addition to more tillage, growers 

are also using pre-plant burndown treatments on their minimum-till acres and are using residual 

herbicides more frequently. They also are moving to multiple herbicide applications over the 

course of the growing season, and are applying herbicides with several different sites of action at 

different times over the course of the season to eliminate weeds (including some HR biotypes). 

Heavily infested fields are being hand-weeded at a cost of up to $100 per acre (Ferrell, 2013). 

While these changes are positive in that they diversify weed control, the cost of these treatments 

poses a substantive threat to soybean production in this region.

HR weeds, particularly GR weeds, are also of increasing concern in all other regions of the U.S. 

Because warmer weather typical of the Southeast region is conducive to the growth and 

propagation of HR annual weeds, this problem is a greater concern in that region than in the 

northern parts of the U.S. However, these weeds are also an ongoing threat in the north. For

136
example, GR weeds, including Palmer amaranth, are becoming more of a concern in parts of the

heartland region (Bowman, 2013; Conley, 2013). 

In parts of the heartland, GR waterhemp and marestail are widespread (Bowman, 2013). No-till 

practices are being used increasingly, but the presence of HR weeds and rapidly increasing 

presence of glyphosate resistance in particular, sometimes necessitate the inclusion of tillage in 

weed control strategies. Some growers who have adopted no-till regimes are using burndown 

herbicides. These commonly include both 2,4-D and glyphosate. Currently, there is little yield 

loss to weeds, indicating that available weed management tools and practices are adequate, but 

the heavy reliance on glyphosate and the presence of GR weeds could necessitate a return to 

more aggressive tillage and adoption of more diversified weed management strategies. 

In the northern Crescent and northern Great Plains (Regions A ,B, G, and H), growers report the 

presence of some GR weeds, but because of climatic differences between the north and south, 

these do not pose the same level of challenge confronting growers in the southern regions of the 

U.S. (Conley, 2013; Meuller, 2013; Sexton, 2013). In the southern regions of the U.S., warm 

temperatures persist beyond the time when soybeans are typically harvested. Once the crop is 

harvested, weed control typically stops. The combination of these conditions provides a 

substantial window of time during which annual weeds can grow and set seed (Ferrell, 2013). In 

the more northern regions, temperatures typically drop soon after harvest, reducing the time 

during which such weeds can grow and spread (Meuller, 2013). However, GR Palmer amaranth 

has been reported in these regions, and there is increasing concern that it could eventually 

become a serious problem. Growers in these regions have adoption rates of GE soybeans 

exceeding 95 percent of the total crop. Much of it consists of GR varieties (Sexton, 2013). 

Adoption of conservation tillage is limited, but several extension scientists from this region 

indicated that it is increasing. However, its adoption is threatened by the occurrence of GR weed 

biotypes. Typically, these growers are using minimal amounts of residual herbicides pre-plant. 

Where burndown herbicide treatments are used, most growers are using tank-mixes containing 

2,4-D and glyphosate.

A variety of strategies have been proposed to help farmers manage GR weeds (Beckie, 2006; 

Boerboom, 1999; Frisvold et al., 2009; Sammons et al., 2007). Resistance management begins 

with good agronomic practices, including the implementation of integrated weed management to 

incorporate diverse weed control practices to reduce the frequency of herbicide applications and 

decrease selection pressure for HR populations (Norsworthy et al., 2012). Integrated Weed 

Management integrates practices such as crop rotation, cover crops, competitive crop cultivars, 

the judicious use of tillage, and targeted herbicide applications to reduce weed populations and 

selection pressures for HR weeds (Mortensen et al., 2012). The Herbicide Resistance Action 

Committee, an industry-based group, has developed the following general principles of weed 

resistance management:

1. Apply integrated weed management practices. Use multiple herbicide sites-of-action 

with overlapping weed spectrums in rotation, sequences, or mixtures;

2. Use the full recommended herbicide rate and proper application timing for the hardest 

to control weed species present in the field;

137
3. Scout fields after herbicide application to ensure control has been achieved. Avoid 

allowing weeds to reproduce by seed or vegetatively; and

4. Monitor site and clean equipment between sites.

For annual cropping situations also consider the following recommendations of the Herbicide 

Resistance Action Committee (www.hracglobal.com):

• Start with a clean field and control weeds early by using a burndown treatment or 

tillage in combination with a pre-emergence residual herbicide as appropriate;

• Use cultural practices such as cultivation and crop rotation, where appropriate; and

• Use good agronomic principles that enhance crop competitiveness.

Under the No Action Alternative, GR weeds are likely to be an increasingly serious concern in 

the southeast, Great Plains and northern crescent regions. Under the No Action Alternative, 

growers would likely use additional herbicides to control weeds. The further adoption of 

conservation tillage practices could be impeded as growers who have already adopted 

conservation tillage are forced to return to more aggressive tillage systems to maintain soybean 

yields (Conley, 2013). The continued emergence of GR weeds will require modifications of crop 

management practices to address these weeds. However, growers are expected to become less 

reliant on glyphosate for weed control as it loses effectiveness. Instead, they are expected to 

depend on additional chemical and non-chemical methods. Changes in management practices 

may include diversifying the mode of action of herbicides applied to corn and soybean and 

making adjustments to crop rotation and tillage practices (Wilson et al., 2011b). Herbicide use 

may increase to meet the need for additional integrated weed management tactics to mitigate HR

weeds in different cropping systems (Culpepper, 2008; Heap, 2011b; Owen & Zelaya, 2005; 

Owen, 2008). Among the herbicides that are predicted to increase in use to control GR weeds are 

2,4-D, chloroacetamide, and glufosinate. There is a trend of increased use of ALS inhibitors, 

PPO inhibitors, and HPPD inhibitors (Appendix 4, Figure 4-3). Selection of weeds resistant to all 

these herbicides is expected to continue. 

Under the Preferred Alternative, 2,4-D use is expected to increase relative to the No Action 

Alternative. However, increases in other herbicides such as chloroacetamides, glufosinate, ALS 

inhibitors, PPO inhibitors, and HPPD inhibitors are expected to be less than under the No Action 

Alternative because EnlistTM crops are expected to be adopted. The availability of inexpensive 

and effective herbicides combined with EnlistTM corn and soybean may delay the adoption of 

non-chemical management strategies under the Preferred Alternative. Fewer growers would be 

expected to adopt aggressive tillage when herbicides remain effective for weed control. Selection 

of weeds resistant to glyphosate, auxins, chloroacetamides, ALS inhibitors, and glufosinate will 

still occur under the Preferred Alternative. The selection pressure for herbicide-resistant weeds 

under the Preferred Alternative relative to the No Action Alternative will depend on the 

management practices employed under each Alternative and cannot be predicted. More 

diversified weed management practices will result in less selective pressure for resistance to any 

given herbicide or management technique.

Likelihood That Use of Enlist DuoTM Will Select for 2,4-D Resistant Weeds

138
The relative risk that a resistant biotype will be selected for a particular herbicide is highly 

correlated to the herbicide site of action (Sammons et al., 2007). Herbicide families have been 

classified according to their risk of resistant weed development. Beckie (2006) lists ALS- and 

ACCase-inhibiting herbicides as high risk for selection of resistant biotypes, while glyphosate 

and auxin type herbicides are considered low risk. Weeds resistant to auxin herbicides have been 

slowly accumulating over the past seventy years, but none have become particularly problematic. 

As of 2014, there are 31 species listed that include biotypes that are resistant to auxin herbicides, 

nine of which are located in the U.S. (Table 16, prepared from data in (Heap, 2013b)). Of the 31

species found world-wide, 17 are known to be resistant to 2,4-D. Of these, 12 are found outside 

the U.S. (Table 16, highlighted in gray) and five are found in the U.S. (waterhemp, spreading 

dayflower, field bindweed, wild carrot, and prickly lettuce (Table 16, highlighted black). Of 

these, GR biotypes are found only for waterhemp. Thus, the combination of glyphosate and 2,4-

D currently controls a wide range of problem weeds. Multiple resistance to 2,4-D and another 

herbicide class has not been reported in the U.S., but has been reported in five weeds species in 

other countries. 

Usually the other resistance is to ALS type herbicides (class 2), though in one case the other 

herbicide resistance is to a Photosystem II inhibitor. Wild radish has a biotype resistant to three 

herbicides (ALS, auxin, and carotenoid inhibitors). 

Despite the fact that glyphosate and auxin herbicides are considered low risk, resistant biotypes 

are being selected from the use of these herbicides. GR weeds in a few species such as Palmer 

amaranth, waterhemp, horseweed, ragweed, and giant ragweed, have become widely prevalent in 

certain areas and cropping systems, such as cotton and soybean, where glyphosate was the only 

herbicide used for weed control and continuous cropping and no-till farming was also practiced. 

The lack of diversity of weed management practices in such situations is believed to have 

contributed significantly to the selection of resistant biotypes. 

Mortensen et al. (2012) argue that increased use of 2,4-D on EnlistTM corn and soybean will 

likely increase the prevalence of 2,4-D resistant weeds. Though auxin herbicide-resistant weeds 

have been relatively slow to develop and are not particularly widespread, they note that the same 

was true for GR weeds prior to the widespread use of glyphosate on GR crops. The selection of 

GR weeds purportedly came about through the almost exclusive use of glyphosate for weed 

control in some crops such as cotton and soybean. Thus, depending on how glyphosate and 2,4-D 

are used on EnlistTM corn and soybean crops, selection of 2,4-D-resistant weeds may be 

preventable. If growers rely exclusively on 2,4-D and glyphosate for weed control, resistance 

might be selected quickly. That is because resistant biotypes against both herbicides already exist 

in a problem weed common to corn and soybean (waterhemp), GR biotypes are found in another 

four problem weeds common to corn and soybean (giant ragweed, kochia, horseweed, and 

ragweed) and a 2,4-D-resistant biotype has been selected in another common problem weed 

(field bindweed) (see Appendix 6, Table 6-3). 

The likelihood of selection of 2,4-D-resistant weeds is greater as the selection pressure for 

resistance increases. Under the Preferred Alternative, selection pressure is expected to be greater 

than the No Action Alternative because 2,4-D use is expected to be higher by 75 to 300 percent

(Appendix 4, Table 4-14). To mitigate the increased selection pressure associated with the 

increased use of 2,4-D, (DAS, 2012) recommends the following practices for herbicide selection:

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• Rotate the use of Enlist DuoTM Herbicide with non-auxin (non-Group 4) and non-glycine 

(Group 9) herbicides 

• Utilize a broad spectrum soil-applied herbicide as a foundation treatment 

• Utilize herbicides with alternative sites of action

• Avoid using more than two applications of a Group 4 herbicide within a single growing 

season unless mixed with another site of action herbicide with overlapping spectrum

• Apply labeled rates of Enlist DuoTM herbicide at the specified time (correct weed size) to 

minimize escapes of tolerant weeds

Third party proprietary data summarized in Appendix 4, Figure 4.3 and Figure 4.4, indicate a 

clear trend of growers following these recommended practices. Growers are using more sites of 

action in both corn and soybean. Corn growers have traditionally relied heavily on soil applied 

non-auxin and non-glyphosate herbicides such as atrazine and chloroacetamide which have 

residual activity and serve as a foundation treatment (Appendix 4, Figure 4.1). Soybean growers 

are showing increased use of this practice with increased use of chloroacetamides, too. Whether 

growers will maintain this trend if the Preferred Alternative is selected is unknown. One 

commenter, an expert in the field, indicated his expectation that chloroacetamides would 

continue to find widespread use in corn and soybean (APHIS-2013-0042-3217). APHIS cannot 

rule out the possibility that some growers will use both EnlistTM soybean and corn in rotation and 

they may rely exclusively on glyphosate and 2,4-D for weed control, contrary to 

recommendations to include additional herbicide chemistries. (Several commenters argued that 

such reliance would be unlikely due to lower efficacy of 2,4-D on weeds compared to glyphosate

(APHIS-2013-0042-1911, 3217, 8196)). Based on the history of selection of GR weeds, it is very 

likely that 2,4-D-resistant weeds will also be selected if exclusive use were to occur.

The selection and distribution of 2,4-D resistant weeds is impossible to predict because the 

extent to which growers use best practices is unknown. A 2010 grower survey (Prince et al., 

2012) observed that many growers were using practices targeted specifically at preventing or 

managing GR weeds, but that these practices were not new introductions to their weed 

management plans. Growers recognized that rotating herbicides, using tank mixes, and 

increasing tillage would be effective strategies to combat GR weeds, but they did not seem to 

recognize that HR weeds were the result of repeated use of a herbicide or herbicides with the 

same site of action (Prince et al., 2012). Education efforts to increase grower awareness are 

ongoing and there appears to be an increase in grower perception of the effectiveness of practices 

recommended by the weed science community (Prince et al., 2012). For example one university 

weed scientist commented on his outreach efforts, (APHIS-2013-0422-1911). According to this 

comment (APHIS-2013-0042-1911), “it is also critical to stress that, at least in Georgia, no weed 

management program relies exclusively on herbicides. The University of Georgia Weed Science 

Extension Team stresses to growers at more than 50 meetings each year that herbicides are only 

one part of the weed management program. Sustainability is only possible with the adoption and 

implementation of diverse management programs and Georgia growers have accepted this 

message as fact (Sosnoskie and Culpepper 2013). Growers are using programs that are complex 

and diverse integrating herbicides, hand weeding, and tillage or cover crops. Neither dicamba nor 

2,4-D would change this approach but would simply be an additional tool to add into these 

management systems.” Under the No Action Alternative, it is likely that the cost of weed 

management and the time spent managing weeds will continue to increase. Modeling studies 

suggest that exclusive use of an herbicide can select for HR weeds in as little as five years (Neve 

140
et al., 2011). Because growers who adopt EnlistTM crops are expected to be those who have had 

the most difficulty with GR weeds, the selection of biotypes exhibiting multiple resistance to 

both glyphosate and 2,4-D is expected to be related to the probability of selecting resistance to 

just 2,4-D and not the product of selecting resistance to both sites of action. Thus, multiple 

resistance could be expected to appear in as little as five years if glyphosate and 2,4-D are used 

exclusively. The southeast (Region D) is expected to be a problem region because GR weeds are 

already reported to be present in greater than 90 percent of cropland (Farm Industry News, 

2013). In this region, Palmer amaranth can no longer be controlled with glyphosate and would be 

a particular risk for the selection of multiple resistant biotypes. In the heartland (Region C and 

G) and prairie states (Region I), HR waterhemp has been selected to several herbicides and a 

biotype resistant to five herbicides has been detected. Furthermore, biotypes with resistance to 

either 2,4-D or glyphosate have already appeared in Nebraska. A multiple resistant biotype could 

form by hybridization and disseminate and independent multiply resistant biotypes to EnlistTM

are likely to be selected if EnlistTM products are exclusively used. 

Table 16. Auxin-Resistant Weeds

Species Year/Location Auxin Situation GR/GT 

1 Amaranthus 

tuberculatus (syn. rudis)

2009 - USA (Nebraska)

2,4-D Pasture +

Common Waterhemp

2 Carduus nutans 1981 - New Zealand 2,4-D Pasture

Musk Thistle

3 Carduus pycnocephalus 1997 - New Zealand 2,4-D Pasture

Italian Thistle

4 Centaurea solstitialis 1988 - USA 

(Washington) Picloram Roadsides

Yellow Starthistle

5 Chenopodium album 2005 - New Zealand Dicamba Corn +

Lambsquarters

6 Cirsium arvense 1979 - Sweden MCPA Cropland

Canada thistle 1985 - Hungary 2,4-D and MCPA Pasture

7 Commelina diffusa 1957 - USA (Hawaii) 2,4-D Sugarcane

Spreading Dayflower

8 Convolvulus arvensis 1964 - USA (Kansas) 2,4-D Cropland

Field Bindweed

9 Daucus carota 1957 - Canada (Ontario) 2,4-D Roadsides

Wild Carrot 1993 - USA (Michigan)

2,4-D

roadsides and 

cropland

1994 - USA (Ohio) 2,4-D soybean

10 Descurainia sophia 2011 - China MCPA winter wheat

Flixweed

11 Digitaria ischaemum 2002 - USA (California) quinclorac rice

Smooth Crabgrass

12 Echinochloa colona 2000 - Colombia quinclorac rice +

Junglerice

13 Echinochloa crus-galli 1998 - USA (Louisiana) quinclorac rice +

Barnyardgrass 1999 - Brazil quinclorac rice

1999 - USA (Arkansas) 

*Multiple - 2 SOA's

propanil and 

quinclorac rice

2000 - China quinclorac rice

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Species Year/Location Auxin Situation GR/GT 

2009 - Brazil *Multiple -

2 SOA's

bispyribac-sodium, 

imazethapyr, 

penoxsulam, and 

quinclorac rice

14 Echinoclhloa crusgalli. 

Var. zelayensis

2013-China

Gulf Cockspur Grass

15 Echinochloa cruspavonis1999 - Brazil

quinclorac rice

Gulf Cockspur

16 Fimbristylis miliacea 1989 - Malaysia 2,4-D rice

Globe Fringerush

17 Galeopsis tetrahit 1998 - Canada (Alberta)

dicamba, fluroxypyr, 

and MCPA

barley, 

cereals, 

cropland, 

wheat

Common Hempnettle

18 Galium spurium 1996 - Canada (Alberta) 

*Multiple - 2 SOA's

imazethapyr, 

metsulfuron-methyl, 

quinclorac, 

sulfometuronmethyl, 

thifensulfuronmethyl, triasulfuron, 

and tribenuronmethyl

cereals and 

wheat

False Cleavers

19 Kochia scoparia 1995 - USA (Montana) dicamba and 

fluroxypyr

cropland and 

wheat +

Kochia 1995 - USA (ND) dicamba wheat

1997 - USA (Idaho) dicamba and 

fluroxypyr roadsides

2010 - USA (Nebraska) dicamba corn

20 Lactuca serriola 2007 - USA 

(Washington)

2,4-D, dicamba, 

MCPA cereals

Prickly Lettuce

21 Limnocharis flava 1995 - Indonesia 2,4-D rice

Yellow bur-head 1998 - Malaysia 

*Multiple - 2 SOA's

2,4-D and 

bensulfuron-methyl rice

22 Limnophila erecta 2002 - Malaysia 

*Multiple - 2 SOA's

2,4-D and ALS 

inhibitors (4) rice

Marshweed

23 Matricaria perforata 1975 - France 2,4-D cereals

Scentless Chamomile 1975 - United Kingdom 2,4-D cereals

24 Papaver rhoeas 1993 - Spain *Multiple -

2 SOA's

2,4-D and 

tribenuron-methyl

cereals and 

wheat

Corn Poppy 1998 - Italy *Multiple - 2 

SOA's

2,4-D and ALS 

inhibitors (2) wheat

1998 - Italy 2,4-D wheat

25 Ranunculus acris 1988 - New Zealand MCPA Pastures

Tall Buttercup

26 Raphanus 

raphanistrum

1999 - Australia 

(Western Australia) 2,4-D cereals

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Species Year/Location Auxin Situation GR/GT 

Wild Radish 2006 - Australia (South 

Australia) *Multiple - 3 

SOA's

2,4-D, diflufenican, 

MCPA, and 

triasulfuron cereals

27 Sinapis arvensis 1990 - Canada 

(Manitoba)

2,4-D, dicamba, 

dichlorprop, MCPA, 

mecoprop, and 

picloram

barley, 

cropland, and 

wheat

Wild Mustard 2008 - Turkey *Multiple 

- 2 SOA's

dicamba, 

propoxycarbazonesodium, 

thifensulfuronmethyl, triasulfuron, 

and tribenuronmethyl not specified

28 Sisymbrium orientale 2005 - Australia (South 

Australia) *Multiple - 2 

SOA's

2,4-D, imazethapyr, 

MCPA, metosulam, 

and metsulfuronmethyl

cereals

Indian Hedge Mustard

29 Soliva sessilis 1999 - New Zealand clopyralid, picloram, 

and triclopyr golfcourses

Carpet Burweed

30 Sphenoclea zeylanica 1983 - Philippines 2,4-D rice

Gooseweed 1995 - Malaysia 2,4-D rice

2000 - Thailand 2,4-D rice

31 Stellaria media 1985 - United Kingdom

mecoprop

cereals and 

wheat

Common Chickweed 2010 - China fluroxypyr and 

MCPA winter wheat

17 species with known resistance to 2,4-D worldwide(gray + black)

12 species with known resistance to 2,4-D outside the U.S. (Gray)

5 species with known resistance to 2,4-D in U.S. (black)

Source: (Heap, 2013b)

Biodiversity

Habitat loss is the greatest direct impact agriculture has on biodiversity (Ammann, 2005). 

Therefore, methods that increase crop yields have the potential to reduce impacts to biodiversity 

by reducing the amount of land converted to agriculture (Carpenter, 2011). Gains in yields have 

generally not been obtained by HR cultivars unless higher yielding ones are modified to 

incorporate an HR trait (NRC, 2010). Yields of corn and soybean have been steadily increasing 

(USDA-NASS, 2014a) and are expected to increase similarly under all alternatives. 

As described in the No Action Alternative and below, agricultural practices can affect 

biodiversity in and around agricultural fields in opposite ways. Growers have the opportunity to 

choose many different practices to manage their operations and therefore it is difficult to make 

generalizations as to how the alternatives will impact biodiversity overall

Agricultural practices have the potential to impact diversity at the farm level by affecting a 

farm’s biota, including birds, wildlife, invertebrates, soil microorganisms, and weed populations. 

Conservation tillage leaves a higher rate of plant residue and increases soil organic matter 

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(Hussain et al., 1999). This benefits soil biota by providing additional food sources (energy) 

(USDA-NRCS, 1996) and increasing the diversity of soil microorganisms. It also benefits 

invertebrate detritivores, their predators, and ultimately, birds and other wildlife higher in the 

food chain (Carpenter, 2011; Towery & Werblow, 2010). Ground-nesting and seed-eating birds, 

in particular, have been found to benefit from greater food and cover associated with 

conservation tillage (SOWAP, 2007). Conservation tillage is expected to be greater under the 

Preferred Alternative. From this aspect, the Preferred Alternative is expected to have a beneficial 

impact on biodiversity. 

Herbicide use in agricultural fields can impact biodiversity by decreasing weed quantities or 

causing a shift in weed species. This can affect insects, birds, and mammals that use these weeds. 

The quantity and type of herbicide use associated with conventional and GE crops depends on 

many variables, including cropping systems, type and abundance of weeds, production practices, 

and individual grower decisions. Weed control is expected to be better under the Preferred 

Alternative. From this aspect, the Preferred Alternative is expected to have a more adverse 

impact on biodiversity. 

Because tillage and herbicide use are expected to have opposing impacts on biodiversity under 

the No Action (more tillage, less effective weed control) and Preferred Alternatives (less tillage, 

more effective weed control), the net impact is unknown. ), 

5.7.3 Natural Resources

Under the Preferred Alternative, there is an expectation that the use of 2,4-D will increase. This 

increase in 2,4-D use has the potential to impact natural resources. APHIS does not regulate the 

use of 2,4-D. The direct and indirect impacts which arise from this increased use are the result of 

the action that EPA is taking with respect to labeling EnlistTM for use on the corn and soybean 

events that are the subject of the three petitions being considered in this EIS. APHIS has 

considered the cumulative impacts from changes in production practices that may arise from HR

weeds.

Soil Quality

The major corn and soybean regions in the U.S. also are areas where soil erosion exceeds 

replacement (See Figure 5 in affected environment). Many of these intensively farmed areas are 

also on highly erodible lands. In some of these areas conservation tillage has been adopted as 

part of the management plan for controlling erosion. 

If conventional tillage increases to control glyphosate- and other herbicide-resistant weeds, there 

may be an impact on soil quality. Residue management that employs intensive tillage and leaves 

low amounts of crop residue on the surface results in greater losses of soil organic matter

(USDA-NRCS, 1996). The total acreage that may be impacted by such an increase in tillage 

would be based on the extent of resistant weeds present in a field and the weed management 

strategy chosen by a grower. Adoption of DAS-40278-9 corn, DAS-68416-4 soybean, and DAS44406-6 soybean can provide growers with an alternative herbicide to glyphosate and 

glufosinate. Intensive use of glyphosate on GR crops has been associated with increased 

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selection for GR weeds. During the comment periods associated with this EIS, any growers 

expressed a need for these Dow events because of their weed problems. 

Based on individual grower needs, these three events could provide growers with an alternative

to intensive tillage practices that may be used to address herbicide resistance issues. This in turn 

could reduce the potential loss of soil organic matter and soil erosion that may result when more 

aggressive tillage practices are used to combat HR weeds under the No Action Alternative. 

However, the selection of weeds resistant to glyphosate, 2,4-D, and glufosinate will limit the use 

of this product and any benefit to soil that may arise. The magnitude of the benefit or the loss of 

the benefit is uncertain because decisions on soil management are up to individual growers. 

Therefore each action contributes incrementally to the problem of soil erosion.

Water Quality

Under the No Action Alternative, increased tillage to manage GR weeds may occur and lead to 

increased soil erosion and decreases in water quality from sedimentation. Under the Preferred 

Alternative, EnlistTM cropping systems for corn and soybean may help to preserve gains in 

conservation tillage in the short term. In the long term, selection of 2,4-D resistant weeds may 

result in similar aggressive tillage practices that are expected to occur under the No Action 

Alternative and negate the benefits mentioned above to the extent that best practices are not 

adopted.

Air Quality

Under the No Action Alternative, increased tillage to manage GR weeds may occur and lead to 

decreased air quality from increased air particulates and exhaust from farm equipment. Under the 

Preferred Alternative, EnlistTM cropping systems for corn and soybean may help to preserve gains 

in conservation tillage and benefit air quality in the short term. In the long term, selection of 2,4-

D resistant weeds may result in similar aggressive tillage practices that are expected to occur 

under the No Action Alternative and negate the benefits mentioned above to the extent that best 

practices are not adopted.

Climate Change

Under the No Action Alternative, there is a potential impact on climate change from increased 

herbicide applications and more aggressive tillage regimes to control herbicide-resistant weeds.

Together, increased herbicide applications and tillage are expected to result in greater burning of 

fossil fuel under the No Action Alternative relative to the Preferred Alternative causing increased 

release of greenhouse gases. Under the Preferred Alternative, EnlistTM cropping systems for corn 

and soybean may help to preserve gains in conservation tillage and reduce greenhouse gas

contributions to climate change in the short term. In the long term, selection of 2,4-D-resistant 

weeds may result in similar aggressive tillage practices that are expected to occur under the No 

Action and negate the benefits mentioned above to the extent that best practices are not adopted.

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5.8 Alternative 3

5.8.1 Socioeconomic and Human Health

Under Alternative 3, only DAS-40278-9 corn would no longer be subject to regulation. DAS68416-4 soybean, and DAS-44406-6 soybean would continue to be regulated. Under this 

alternative, 2,4-D for crop use is predicted to increase 36 to 169 percent relative to the No Action 

Alternative (Appendix 4, Table 4-14), but is less than the increase expected under the Preferred 

Alternative. The increased use of 2,4-D may increase the selection of 2,4-D-resistant weeds, 

which might increase the costs for weed control in small grain cereals, cotton, sorghum, soybean,

and fallow applications. The pressure for selecting 2,4-D-resistant weeds is expected to be lower 

in Alternative 3 than Alternative 2 because 2,4-D-resistant soybeans will not be grown 

eliminating the possibility that growers will exclusively use Enlist DuoTM in their corn soybean 

rotations. Because 2,4-D can already be used on corn, it is possible that growers will be less 

likely to adopt DAS-40278-9 corn if DAS-68416-4 soybean and DAS-44406-6 soybean are not 

also available. If the adoption rate of DAS-40278-9 corn is lower than predicted, the impacts of 

Alternative 3 would likely be more similar to the No Action Alternative. 

No cumulative impacts from the changes in production practices were identified on Human 

Health for any of the alternatives. EPA considers the direct and indirect impacts from herbicide 

use on Human Health as part of their regulatory decision. Therefore those impacts are outside the 

scope of this FEIS.

5.8.2 Biological Resources 

Depending on the adoption rate of DAS-40278-9 corn as well as the management practices 

employed by growers, there may be an increase in the selection of 2,4-D-resistant weeds under 

Alternative 3 relative to the No Action Alternative. If EnlistTM corn is widely adopted, overall 

2,4-D use can increase by 19% to 91% relative to the No Action alternative (Table 4-12). On 

corn only, the increase in 2,4-D use may be 100 to 500% (Table 4-12). The impact of increased 

2,4-D use on the selection of 2,4-D resistant weeds may be mitigated by best management 

practices (see section 5.7.2), lessening the difference between the No Action and Preferred 

Alternatives. Similarly, if EnlistTM corn is not widely adopted, 2,4-D use is not expected to be 

different between the No Action Alternative and Alternative 3 with no corresponding differences 

in the selection of 2,4-D resistant weeds under the two Alternatives. As noted in Appendix 4, 

EnlistTM corn might not be widely adopted because Dow’s market share in corn is under 5%. 

Furthermore as corn is already resistant to 2,4-D for at least part of its growth cycle, growers 

may not value this trait enough to switch to Dow corn varieties from the more widely used 

competitor varieties. The selection of 2,4-D-resistant weeds is expected to be less under 

Alternative 3 than under the Preferred Alternative because the availability of EnlistTM soybeanis 

expected to further increase 2,4-D use and could facilitate the continuous use of 2,4-D in a cornsoybean rotation under the latter. 

5.8.3 Natural Resources

If conservation tillage practices were to decrease, natural resources could be impacted. However, 

corn growers still have several effective herbicide chemistries to control GR weeds, including 

146
atrazine and chloroacetamides. Consequently, under Alternative 3, tillage practices for corn 

growers are not expected to differ compared to the No Action Alternative.

5.9 Alternative 4

5.9.1 Socioeconomic and Human Health

Under Alternative 4, DAS-68416-4 soybean and DAS-44406-6 soybean would be granted 

nonregulated status but DAS-40278-9 corn would continue to be regulated. Under this 

alternative, 2,4-D for crop use is predicted to increase 39 to 139 percent relative to the No Action 

Alternative (Appendix 4, Table 4-14), but is less than the increase expected under the Preferred 

Alternative. The increased use of 2,4-D may increase the selection of 2,4-D-resistant weeds 

which might increase costs for weed control in small grain cereals, cotton, sorghum, soybean,

and fallow applications. The pressure for selecting 2,4-D-resistant weeds is expected to be lower 

in Alternative 4 than the Preferred Alternative because there would be additional 2,4-D use on 

EnlistTM corn under the latter and the possibility of continuous use of 2,4-D in a corn-soybean 

rotation. Because soybeans are very sensitive to 2,4-D, EnlistTM soybeans would allow a new 

post-emergent use of 2,4-D in contrast to corn, where such uses are already possible because of 

inherent tolerance of corn to 2,4-D. Because soybean growers also have fewer effective 

herbicides to manage weeds than corn growers, EnlistTM soybean is expected to be more widely 

adopted than EnlistTM corn. The wide appeal of EnlistTM soybean relative to corn is indicated by 

the licensing agreements Dow has made for the EnlistTM trait in 35% of the soybean market

(Appendix 4). In contrast they have not made any licensing agreements for the EnlistTM trait in 

the corn market and Dow’s market share in corn is under 5%. (Appendix 4). Even though 

EnlistTM corn will not be grown under Alternative 4, the pressure for selection of 2,4-D-resistant 

weeds is expected to be greater under Alternative 4 than under Alternative 3 because EnlistTM

products can be used for both pre- and post-emergent applications on both corn and EnlistTM

soybean. Furthermore, EnlistTM soybean under Alternative 4 is expected to be more widely 

adopted than EnlistTM corn under Alternative 3 resulting in greater 2,4-D use under Alternative 4. 

Consequently the likelihood for the selection of 2,4-D resistant weeds is higher under Alternative 

4 than Alternative 3 or the No Action Alternative.

No cumulative impacts were identified on Human Health for any of the alternatives.

5.9.2 Biological Resources

Depending on the adoption rate of DAS-68416-4 and DAS-44406-6 soybean, and the 

management practices used by growers, there may be an increase in the selection of 2,4-Dresistant weeds under Alternative 4 relative to the No Action Alternative. The selection of 2,4-Dresistant weeds is expected to be less than under the Preferred Alternative. 

5.9.3 Natural Resources

If conservation tillage practices were to diminish, natural resources could be impacted. Under the 

No Action Alternative, soybean growers are expected to use less conservation tillage in areas 

where GR weeds are poorly controlled by herbicides. Under Alternative 4, weed control by 

herbicides is expected to be more effective in soybean than under the No Action Alternative. 

Therefore, conservation tillage practices are expected to be more widely practiced under 

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Alternative 4 than under the No Action Alternative and Natural Resources are less likely to be 

adversely impacted. 

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6 OTHER IMPACTS AND MITIGATION MEASURES 

This section describes other potential impacts associated with the implementation of the Action 

Alternatives, including unavoidable impacts; short-term versus long-term productivity of the 

environment; and irreversible/irretrievable commitment of resources. This section also describes 

potential impact mitigation measures, as applicable, beyond what is already built into the 

Alternatives. 

6.1 Unavoidable Impacts

Unavoidable impacts are any adverse environmental effects which cannot be avoided, should the 

proposal be implemented (40 CFR § 1502.16). Herbicides represent a tool that allows for the 

economical production of corn and soybean. As long as herbicides are used to produce corn and 

soybean, selection of weeds resistant to the herbicides will occur. Under all four Alternatives, the 

selection of herbicide-resistant weeds is an unavoidable impact. Growers may mitigate the rate at 

which weeds develop resistance by adopting best management practices as described in Section 

5.7.2. APHIS does not have the authority to regulate grower management practices, nor does 

APHIS have the authority to regulate herbicide use.

6.2 Short Term Versus Long Term Effects

In the short term, corn and soybean growers who adopt EnlistTM corn and soybean are likely to 

experience more efficient and less costly control of GR weeds. Adopters may be better able to 

maintain conservation tillage programs on their farms. Growers of non-GE crops and nonadopters of the EnlistTM crops may experience a decline in the weed seed bank as overall weed 

control improves on neighboring farms. 

Over the long term, as weeds develop resistance to 2,4-D and multiple resistance to 2,4-D and 

glyphosate, the efficiency of weed control will diminish and the cost will increase. Some growers 

may need to employ more aggressive tillage to manage resistant weeds. Adoption of 

conventional tillage would be expected to result in greater soil erosion, loss of organic matter, 

soil compaction, and reduced moisture holding capacity, as compared to conservation or reduced 

tillage methods. This would lead to an increase in potential sedimentation and turbidity in nearby 

surface waters during rain and irrigation events and adverse impacts to biological resources. Non 

adopters and growers of non-GE crops will again be impacted by weeds from neighboring farms

(see section 5.7.1). Growers of small cereal crops, that rely on 2,4-D for managing weeds in their 

crops, will experience greater weed control costs as alternatives to 2,4-D are usually more costly. 

6.3 Irreversible Resource Commitments 

Irreversible resource commitments represent a loss of future options. It applies primarily to the 

use of nonrenewable resources and to factors that are renewable only over long time spans, or to 

adverse impacts that cannot be reversed once they are set in motion. An irretrievable 

commitment of resources represents opportunities that are foregone for the period of the 

proposed action. It also includes the use of renewable resources, such as timber or human effort, 

as well as other utilization opportunities that are foregone in favor of the proposed action. 

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No irreversible or irretrievable commitments of resources were identified with the Action 

Alternatives.

6.4 Mitigation Measures 

As defined in the CEQ regulations for implementing NEPA (40 CFR § 1508.20) mitigation 

includes: 

• avoiding the impact altogether by not taking a certain action or parts of an action; 

• minimizing impacts by limiting the degree or magnitude of the action and its 

implementation; 

• rectifying the impact by repairing, rehabilitating, or restoring the affected environment; 

• reducing or eliminating the impact over time by preservation and maintenance operations 

during the life of the action; and 

• compensating for the impact by replacing or providing substitute resources or 

environments.

APHIS does not have the authority to regulate types of management practices or use of 

herbicides. Mitigation measures to oversee the proper usage of herbicides are determined by 

EPA and are disseminated to the herbicide users through EPA approved labels. Spray drift 

mitigation language on the label is intended to limit off site transport of 2,4-D choline salt in 

spray drift. Weed resistance mitigation language is intended to encourage best practices to 

minimize selection of resistant weeds and to aggressively and quickly respond to cases of 

outbreaks to minimize spread. Local governments may also impose restrictions on when and how 

herbicides can be applied (see Appendix 7). 

Dow has taken an active role to foster good stewardship practices with EnlistTM users. All 

EnlistTM users will be subject to a stewardship agreement. The stewardship agreement is based in 

part on discussions with the EPA and the Save Our Crops Coalition, a group of farmers who 

raise 2,4-D sensitive crops. In an agreement with the Save Our Crops Coalition, Dow has 

proposed a strategy to mitigate adverse environmental effects of Enlist DuoTM, through label 

language specified by EPA, through limitations on application timing, and through the 

competitive pricing of lower volatility formulations (APHIS-2013-0042-7255). Based on the 

proposed registration, the lower volatility formulation is the only one that can lawfully be 

applied to EnlistTM crops. In addition Dow has proposed recordkeeping practices to ensure that 

applicators are aware and have documented application location, timing, and windspeed in an 

effort to increase applicator compliance with their responsibilities under the label requirements

(APHIS-2013-0042-7255). 

Dow committed to the following measures to foster compliance with the stewardship agreement 

aimed to reduce off-target movement of herbicides (APHIS-2013-0042-7255). These are:

1. Dow commits to assist in the investigation, diagnosis and resolution of alleged non-target

claims.

2. Dow commits to include terms within its Technology Use Agreements for 2,4‐D tolerant 

crops that require growers and applicators to keep accurate records of the locations where 

150
2,4‐D tolerant crops are planted and where authorized herbicides containing 2,4‐D 

choline salt are applied, and to retain invoices for all seed and herbicide purchases.

3. Dow commits to include language in its Product Use Guide for authorized herbicides

containing 2,4‐D choline salt that recommends applicators keep accurate spray records, 

including application location, timing, and wind speed.

4. Dow commits to utilize an independent third party to collect seed and pesticide sales data 

that will help identify applicators that use non‐choline salt forms of 2,4‐D (generic 2,4‐D) 

in contravention of present generic 2,4‐D label requirements and the Technology Use 

Agreement.

5. DAS commits to price its technology (both its seeds and its herbicide) competitively to 

maximize the use of 2,4‐D choline salt (and disincentivize the use of non‐choline salt 

formulations of 2,4‐D) on 2,4‐D tolerant crops.

In addition, EPA has concluded in its proposed registration for Enlist DuoTM, that “in order to 

mitigate risks to non-target plants and animals, label language will be required that is intended to 

keep the pesticide on the treatment area, thereby reducing the potential for exposure of nontarget plants and animals” (US-EPA, 2014). Applicator responsibilities include requirements for 

specific techniques to reduce the possibility of spray drift such as nozzle type to control droplet 

size, maximum wind speeds, and a 30 foot downwind buffer for sensitive areas (US-EPA, 2014). 

In addition, surface and ground water advisories will be required on all labeling, which may 

further reduce residues in drinking water and exposure of non-target organisms (US-EPA, 2014). 

EPA has also proposed to grant the registration for Enlist DuoTM with certain terms necessary to 

ensure that if weed resistance is likely, EPA can act quickly to address the problem (US-EPA, 

2014). The registration requires Dow to develop a stewardship program that will aggressively 

promote resistance management efforts (US-EPA, 2014). The plan mandates scouting 

requirements prior to and after herbicide application and reporting any non-performance issues to 

Dow who in turn must respond immediately to ensure that possible incidents of resistance are 

promptly investigated and resolved. Best practices included on the label include among others:

rotating herbicide chemistries, limiting herbicide applications/season, incorporating non 

chemical weed control strategies, and preventing weeds from setting seed. The stewardship 

program also includes educating and training retailers, farmers, and applicators on the 

appropriate use of EnlistTM technology, reporting verified cases of resistance to Enlist DuoTM to 

interested parties, and monitoring whether Enlist DuoTM is being used on EnlistTM seed.

University extension agents are also engaged in educating growers on best practices for weed 

management (see for example comment to the docket APHIS-2013-0042-1911. “At least in 

Georgia, no weed management program relies exclusively on herbicides. The University of 

Georgia Weed Science Extension Team stresses to growers at more than 50 meetings each year 

that herbicides are only one part of the weed management program. Sustainability is only 

possible with the adoption and implementation of diverse management programs and Georgia 

growers have accepted this message as fact (Sosnoskie and Culpepper 2013). Growers are using 

programs that are complex and diverse integrating herbicides, hand weeding, and tillage or cover 

crops. Neither dicamba nor 2,4-D would change this approach but would simply be an additional 

tool to add into these management systems.”

The EPA concluded that “(i) the Agency has satisfactory data pertaining to the proposed uses of 

Enlist DuoTM on corn and soybeans; and (ii) approving this application as set forth below will not 

151
cause any unreasonable adverse effect on the environment. Though the data support the 

conclusion that no unreasonable adverse effects on the environment will occur when Enlist 

DuoTM is used as specified on the label, there is uncertainty to the extent it will be used 

unlawfully and contrary to the label requirements. There is also uncertainty regarding the extent 

to which EnlistTM technology users will follow the best practices for managing weed resistance 

as set forth on the label or how aggressively Dow will pursue record keeping and auditing 

results. There is uncertainty regarding the price of Enlist DuoTM, but if pricing is competitive, it 

seems likely that most growers will not risk harming their neighbors or their relationship with 

Dow by using the more volatile 2,4-D formulations. Measures are in place to quickly identify, 

report, and resolve outbreaks of resistant weeds. As this is a new program, there is uncertainty as 

to how effective these measures will be.”

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7 THREATENED AND ENDANGERED SPECIES

The Endangered Species Act (ESA) of 1973, as amended, is one of the most far-reaching 

wildlife conservation laws ever enacted by any nation. Congress passed the ESA to prevent 

extinctions facing many species of fish, wildlife and plants. The purpose of the ESA is to 

conserve endangered and threatened species and the ecosystems on which they depend as key 

components of America’s heritage. To implement the ESA, the U.S. Fish & Wildlife Service 

(USFWS) works in cooperation with the National Marine Fisheries Service (NMFS), other 

Federal, State, and local agencies, Tribes, non-governmental organizations, and private citizens. 

Before a plant or animal species can receive the protection provided by the ESA, it must first be 

added to the Federal list of threatened and endangered wildlife and plants.

A species is added to the list when it is determined by the USFWS/NMFS to be endangered or 

threatened because of any of the following factors:

• The present or threatened destruction, modification, or curtailment of its habitat or range;

• Overutilization for commercial, recreational, scientific, or educational purposes;

• Disease or predation;

• The inadequacy of existing regulatory mechanisms; and

• The natural or manmade factors affecting its survival.

Once an animal or plant is added to the list, protective measures apply to the species and its 

habitat. These measures include protection from adverse effects of federal activities. 

Section 7 (a)(2) of the ESA requires that federal agencies, in consultation with USFWS and/or 

the NMFS, ensure that any action they authorize, fund, or carry out is “not likely to jeopardize 

the continued existence of a listed species or result in the destruction or adverse modification of 

designated critical habitat.” It is the responsibility of the federal agency taking the action to 

assess the effects of their action and to consult with the USFWS and NMFS if it is determined 

that the action “may affect” listed species or designated critical habitat. To facilitate their ESA 

consultation requirements, APHIS met with the USFWS from 1999 to 2003 to discuss factors 

relevant to APHIS’ regulatory authority and effects analysis for petitions for nonregulated status

and developed a process for conducting an effects determination consistent with the Plant 

Protection Act (PPA) of 2000 (Title IV of Public Law 106-224). APHIS uses this process to 

help fulfill its obligations and responsibilities under Section 7 of the ESA for biotechnology 

regulatory actions.

APHIS met with USFWS officials on June 15, 2011, to discuss whether APHIS has any 

obligations under the ESA regarding analyzing the effects of herbicide use associated with all 

GE crops on threatened and endangered species (TES). As a result of these joint discussions, 

USFWS and APHIS have agreed that it is not necessary for APHIS to perform an ESA effects 

analysis on herbicide use associated with GE crops currently planted because EPA has both 

regulatory authority over the labeling of pesticides and the necessary technical expertise to assess 

pesticide effects on the environment under FIFRA. APHIS has no statutory authority to authorize 

or regulate the use of 2,4-D, quizalofop, glufosinate, glyphosate, or any other herbicide, by corn 

and soybean growers. Under APHIS’ current part 340 regulations, APHIS only has the authority 

to regulate DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 corn or any GE 

organism as long as APHIS believes they may pose a plant pest risk (7 CFR part 340.1). APHIS 

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has no regulatory jurisdiction over any other risks associated with GE organisms, including risks 

resulting from the use of herbicides or other pesticides on those organisms. 

After completing a plant pest risk analysis, if APHIS determines that DAS-68416-4 soybean, 

DAS-44406-6 soybean, or DAS-40278-9 corn seeds, plants, or parts thereof do not pose a plant 

pest risk, then these articles would no longer be subject to the plant pest provisions of the PPA or 

to the regulatory requirements of 7 CFR Part 340. As part of its EIS analysis, APHIS is 

analyzing the potential effects of DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS40278-9 corn on the environment including, as required by the ESA, any potential effects on

threatened and endangered species and critical habitat. As part of this process, APHIS 

thoroughly reviews the GE product information and data related to the organism (generally a 

plant species, but may also be other genetically engineered organisms). For each 

transgene/transgenic plant, APHIS considers the following: 

• A review of the biology and taxonomy of the crop plant and its sexually compatible 

relatives;

• Characterization of each transgene with respect to its structure and function and the 

nature of the organism from which it was obtained;

• A determination of where the new transgene and its products (if any) are produced in the 

plant and their quantity;

• A review of the agronomic performance of the plant, including disease and pest 

susceptibilities, weediness potential, and agronomic and environmental impacts;

• Determination of the concentrations of known plant toxicants (if any are known in the 

plant);

• Analysis to determine if the transgenic plant is sexually compatible with any TES of 

plants or a host of any TES; and

• Any other information that may inform the potential for an organism to pose a plant pest

risk.

In following this review process, APHIS, as described below, has evaluated the potential effects 

that a determination of nonregulated status of DAS-68416-4 soybean, DAS-44406-6 soybean, 

and DAS-40278-9 corn may have, if any, on federally-listed TES species and species proposed 

for listing, as well as designated critical habitat and habitat proposed for designation. Based upon 

the scope of the EIS and production areas identified in the Affected Environment section of the 

EIS, APHIS reviewed the USFWS list of TES species (listed and proposed) for each state where 

soybean and corn are commercially produced from the USFWS Environmental Conservation 

Online System (USFWS, 2014a; b; c). 

Prior to this review, APHIS considered the potential for DAS-68416-4 soybean, DAS-44406-6 

soybean, and DAS-40278-9 corn to extend the range of soybean and corn production and also the 

potential to extend agricultural production into new natural areas. APHIS has determined that 

agronomic characteristics and cultivation practices required for DAS-68416-4 soybean, DAS44406-6 soybean, and DAS-40278-9 corn are essentially indistinguishable from practices used to 

grow other corn and soybean varieties, including other herbicide-tolerant varieties(DAS, 2010a; 

b; 2011a; USDA-APHIS, 2010b; 2012a; b). Although DAS-68416-4 soybean, DAS-44406-6 

soybean, and DAS-40278-9 corn may be expected to replace other varieties of corn and soybean 

currently cultivated, APHIS does not expect the cultivation of these to result in new corn or 

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soybean acres to be planted in areas that are not already devoted to agriculture. Accordingly, the 

issues discussed herein focus on the potential environmental consequences of the determination 

of nonregulated status of DAS-68416-4 soybean, DAS-44406-6 soybean, and DAS-40278-9 corn

on TES species in the areas where corn and soybean are currently grown.

For its analysis on TES plants and critical habitat, APHIS focused on the agronomic differences 

between the regulated articles and corn and soybean varieties currently grown; the potential for 

increased weediness; and the potential for gene movement to native plants, listed species, and 

species proposed for listing. 

For its analysis of effects on TES animals, APHIS focused on the implications of exposure to the

novel proteins expressed in the plants as a result of the transformation, and the ability of the 

plants to serve as a host for a TES. The novel proteins associated with DAS-68416-4 soybean, 

DAS-44406-6 soybean, and DAS-40278-9 corn are listed in Table 17.

Table 17. DAS Corn and Soybean Lines

Regulated Article Protein Phenotypic Effects

DAS-40278-9 corn

aryloxyalkanoate 

dioxygenase (AAD-1)

Resistance to herbicides of

the aryloxyalkanoate family, 

including phenoxy auxins 

(e.g. 2,4-D) and AOPP

ACCase inhibitors.

DAS-68416-4 soybean

aryloxyalkanoate 

dioxygenase-12 (AAD-12)

Resistance to 2,4-D

phosphinothricin 

acetyltransferase (PAT)

Resistance to glufosinate

DAS-44406-6 soybean

aryloxyalkanoate 

dioxygenase-12 (AAD-12)

Resistance to 2,4-D

phosphinothricin 

acetyltransferase (PAT)

Resistance to glufosinate

modified 5-

enolpyruvylshikimate-3-

phosphate synthase (EPSPS)

Resistance to glyphosate

7.1 Potential Effects of DAS-40278-9 Corn on TES and Critical Habitat

7.1.1 Threatened and Endangered Plant Species and Critical Habitat

The agronomic and morphologic characteristics data provided by DAS were used in the APHIS 

analysis of the weediness potential for DAS-40278-9 corn, and evaluated for the potential to 

impact TES and critical habitat. Agronomic studies conducted by Dow tested the hypothesis that 

the weediness potential of DAS-40278-9 corn is unchanged with respect to conventional corn 

(DAS, 2010a). No differences were detected between DAS-40278-9 corn and non-transgenic 

corn in growth, reproduction, or interactions with pests and diseases, other than the intended 

effect of tolerance to the two herbicides (USDA-APHIS, 2010b). Corn possesses few of the 

characteristics of successful weeds, and has been cultivated around the globe without any report 

that it is a serious weed or that it forms persistent feral populations (USDA-APHIS, 2010b). 

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However, corn seed can germinate in undesired locations and would then be considered a weed, 

such as when corn emerges as a volunteer in a soybean rotation following a corn crop (USDAAPHIS, 2010b). 

Because the expression of the AAD-1 protein in DAS-40278-9 corn results in greater tolerance 

to two herbicides, there would be fewer options for controlling volunteer corn. However, as there 

are multiple options for control of volunteer corn, including the use of other ACCase inhibitor 

herbicides (e.g., the cyclohexadione “dim” herbicides clethodim or sethoxydim) and acetolactate 

synthesis inhibitors (ALS; e.g., imazamox, imazequin, and imazethapyr) (Heap, 2011a; WSSA, 

2011), the expression of the AAD-1 protein herbicide-tolerance trait in DAS-40278-9 corn is 

unlikely to appreciably improve seedling establishment or increase weediness potential. Based 

on the agronomic field data and literature survey on corn weediness potential, DAS-40278-9 

corn is unlikely to affect TES or critical habitat as a troublesome or invasive weed (USDAAPHIS, 2010b).

APHIS evaluated the potential of DAS-40278-9 corn to cross with listed species. After reviewing 

the list of threatened and endangered plant species in the States where corn is grown, APHIS 

determined that DAS-40278-9 corn would not be sexually compatible with any listed threatened 

or endangered plant species or plant proposed for listing as none of these listed plants are in the 

same genus nor are known to cross pollinate with species of the genus Zea.

Based on agronomic field data, literature surveyed on corn weediness potential, and no sexually 

compatibility of TES with corn, APHIS has concluded that DAS-40278-9 corn will have no 

effect on threatened or endangered plant species or on critical habitat.

7.1.2 Threatened and Endangered Animal Species

Threatened and endangered animal species that may be exposed to the gene products in DAS40278-9 corn would be those TES that inhabit corn fields and feed on DAS-40278-9 corn. As 

discussed further in Section 3.3.1, Affected Environment, Biological Resources, Animal 

Communities, cornfields are generally considered poor habitat for birds and mammals in 

comparison with uncultivated lands, but the use of cornfields by birds and mammals is not 

uncommon. Some birds and mammals use cornfields at various times throughout the corn 

production cycle for feeding and reproduction. Most birds and mammals that utilize cornfields 

are ground foraging omnivores that feed on corn seed, sprouting corn, and the corn remaining in 

the fields following harvest. Few, if any, TES are likely to use corn fields because they do not 

provide suitable habitat. For birds, only whooping crane (Grus americana), Mississippi sandhill 

crane (Grus canadensis pulla), piping plover (Charadrius melodus), interior least tern (Sterna 

antillarum), and Sprague’s pipit (Anthus spragueii; a candidate species) occasionally feed in 

farmed sites (USFWS, 2011a). These bird species may visit corn fields during migration (Krapu 

et al., 2004; USFWS, 2011a). The whooping crane in particular spends the majority of its 

foraging time during migration in agricultural fields, although its diet during this time is not well 

understood (Canadian Wildlife Service and U.S. Fish and Wildlife Service, 2007; ICF, 2014)As 

discussed thoroughly in Section 3.3.1, many mammals may feed on corn; especially white tailed 

deer, raccoons, and mice and voles. As for listed species, the Louisiana black bear (Ursus 

americanus luteolus), occurring in Louisiana, Mississippi, and Texas (Johnsen et al., 2005), may 

occasionally forage on corn among other crops such as sugarcane, winter wheat, and soybean

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(MSU, No Date). APHIS considered the risks to threatened and endangered animals from 

consuming DAS-40278-9 corn. Dow has presented information on the food and feed safety of 

the AAD-1 protein, comparing the DAS-40278-9 corn variety with conventional varieties and 

evaluating the differences between varieties with and without herbicide applications (DAS, 

2010a). Compositionally, DAS-40278-9 corn grain was determined to be the same as 

conventional varieties. Compositional elements compared included moisture, protein, fat, 

carbohydrates, ash, minerals, dietary fiber, essential and non-essential amino acids, fatty acids, 

vitamins, and antinutrients (DAS, 2010a; Herman et al., 2010). The results presented by Dow

show that the incorporation of the aad-1 gene and the attendant expression of the AAD-1 protein 

in DAS-40278-9 corn does not result in any biologically-meaningful differences between DAS40278-9 corn grain and the non-transgenic hybrid grain. 

Dow conducted safety evaluations based on Codex Alimentarius Commission procedures to 

assess any potential adverse effects to humans or animals resulting from environmental releases 

and consumption of DAS-40278-9 corn (DAS, 2010a; FAO, 2009; US-FDA, 2011b). These 

safety studies included evaluating protein structure and function, including homology searches of 

the amino acid sequences with comparison to all known allergens and toxins, an in vitro 

digestibility assay of the proteins, an acute oral toxicity feeding study in mice, and a feeding 

study in broiler chickens (DAS, 2010a; Herman et al., 2011a; Herman et al., 2010; US-FDA, 

2011b). The DAS-40278-9 corn AAD-1 protein was determined to have no amino acid sequence 

similar to known allergens, lacked toxic potential to mammals, and was degraded rapidly and 

completely in gastric fluid (DAS, 2010a; US-FDA, 2011b).

In addition to evaluating Dow’s comparisons of DAS-40278-9 corn with the non-transgenic 

near-isoline hybrid variety for potential differences in agronomic and morphology, APHIS also 

considers the FDA regulatory assessment in making its determination of the potential impacts of 

a determination of nonregulated status of the new agricultural product. DAS-40278-9 corn would 

be the first commercially available food crop expressing the AAD-1 protein. In that regard, DAS

has submitted food and feed safety and nutritional assessments for DAS-40278-9 corn to the 

FDA. At this time, the FDA considers the consultation on DAS-40278-9 corn to be complete 

(US-FDA, 2011b).

APHIS considered the possibility that DAS-40278-9 corn could serve a host plant for a 

threatened or endangered species. (i.e., a listed insect or other organism that may use the corn

plant to complete its lifecycle). A review of the species list reveals that there are none that would 

use corn as a host plant (USFWS, 2014a; b).Considering the compositional similarity between 

DAS-40278-9 corn and other varieties currently grown and the lack of toxicity and allergenicity 

of the AAD-1 protein, APHIS has concluded that exposure and consumption of DAS-40278-9 

corn grain would have no effect on threatened or endangered animal species.

7.1.3 Summary

After reviewing the possible effects of allowing the environmental release of DAS-40278-9 corn, 

APHIS has not identified any stressor that could affect the reproduction, numbers, or distribution 

of a listed TES or species proposed for listing. As a result, a detailed exposure analysis for 

individual species is not necessary. APHIS also considered the potential effect of a determination 

of nonregulated status of DAS-40278-9 corn on designated critical habitat or habitat proposed 

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for designation, and could identify no differences from effects that would occur from the 

production of other corn varieties. Corn is not considered a particularly competitive plant species 

and has been selected for domestication and cultivation under conditions not normally found in 

natural settings (US-EPA, 2010a). Corn is not sexually compatible with, or serves as a host 

species for, any listed species or species proposed for listing. Consumption of DAS-40278-9 

corn by any listed species or species proposed for listing will not result in a toxic or allergic 

reaction. Based on these factors, APHIS has concluded that a determination of nonregulated 

status of DAS-40278-9 corn, and the corresponding environmental release of this corn variety 

will have no effect on listed species or species proposed for listing, and would not affect 

designated habitat or habitat proposed for designation. Because of this no-effect determination, 

consultation under Section 7(a)(2) of the Act or the concurrence of the USFWS or NMFS is not 

required.

7.2 Potential Effects of DAS-68416-4 Soybean and DAS-444406-06 Soybean on TES

and Critical Habitat

7.2.1 Threatened and Endangered Plant Species and Critical Habitat

The agronomic and morphologic characteristics data provided by Dow were used in the APHIS 

analysis of the weediness potential for DAS-68416-4 soybean and DAS-44406-6 soybean, and 

further evaluated for the potential to impact TES and critical habitat. Agronomic studies 

conducted by Dow tested the hypothesis that the weediness potential of DAS-68416-4 soybean

and DAS-44406-6 soybean is unchanged with respect to conventional soybean (DAS, 2010b; 

2011b). No differences were detected between DAS-68416-4 soybean and DAS-44406-6 

soybean and non-transgenic soybean in growth, reproduction, or interactions with pests and 

diseases, other than the intended effect of herbicide tolerance (DAS, 2010b; 2011a; USDAAPHIS, 2012b). Soybean possesses few of the characteristics of successful weeds, and has been 

cultivated around the globe without any report that it is a serious weed or that it forms persistent 

feral populations (USDA-APHIS, 2010b). Soybean cannot survive in most of the U.S. without 

human intervention, and it is easily controlled if volunteers appear in subsequent crops (see 

Subsection 4.1.2, No Action Alternative – Biological Resources). The expression of the AAD-12, 

PAT, and EPSPS proteins providing the herbicide tolerance traits in DAS-68416-4 soybean and 

DAS-44406-6 soybean are unlikely to appreciably improve seedling establishment or increase 

weediness potential (DAS 2010, DAS 2011). APHIS has concluded the approval of a petition of 

nonregulated status for DAS-68416-4 soybean and DAS-44406-6 soybean does not present a risk 

of weediness, and does not present an increased risk of gene flow when compared to other 

currently cultivated soybean varieties (USDA-APHIS, 2012a; b). 

APHIS evaluated the potential of DAS-68416-4 soybean and DAS-44406-6 soybean to cross 

with listed species. As previously discussed in the analysis of Gene Movement and Weediness 

and Plants, APHIS has determined that there is no risk to unrelated plant species from the 

cultivation of DAS-68416-4 soybean and DAS-44406-6 soybean. Soybean is highly selfpollinating and can only cross with other members of Glycine subgenus Soja. Wild soybean 

species are endemic in China, Korea, Japan, Taiwan and the former USSR; in the U.S. there are 

no Glycine species found outside of cultivation and the potential for outcrossing is minimal 

(OECD, 2000). After reviewing the list of threatened and endangered plant species in the U.S. 

states where soybean is grown, APHIS determined that DAS-68416-4 soybean and DAS-44406-

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6 soybean would not be sexually compatible with any listed threatened or endangered plant 

species proposed for listing, as none of these listed plants are in the same genus nor are known to 

cross pollinate with species of the genus Glycine.

Based on agronomic field data, literature surveyed on soybean weediness potential, and no 

sexual compatibility of TES with soybean, APHIS has concluded that DAS-68416-4 soybean

and DAS-44406-6 soybean will have no effect on threatened or endangered plant species or 

critical habitat.

7.2.2 Threatened and Endangered Animal Species

Threatened and endangered animal species that may be exposed to the gene products in DAS68416-4 soybean and DAS-44406-6 soybean would be those TES that inhabit soybean fields and 

feed on DAS-68416-4 soybean and DAS-44406-6 soybean. To identify potential effects on 

threatened and endangered animal species, APHIS evaluated the risks from consuming DAS68416-4 soybean and DAS-44406-6 soybean. 

Soybean commonly is used as a feed for many livestock. Additionally, wildlife may use 

soybean fields as a food source, consuming the plant or insects that live on the plants, although 

TES generally are found outside of agricultural fields. Few if any TES are likely to use soybean 

fields because they do not provide suitable habitat. Only whooping crane (Grus americana), 

Mississippi sandhill crane (Grus canadensis pulla), piping plover (Charadrius melodus), interior 

least tern (Sterna antillarum), and Sprague’s pipit (Anthus spragueii; a candidate species) 

occasionally feed in farmed sites (USFWS, 2011a). These bird species may visit soybean fields 

during migratory periods, but would not be present during normal farming operations (Krapu et 

al., 2004; USFWS, 2011a). In a study of soybean consumption by wildlife in Nebraska, results 

indicated that soybeans do not provide the high energy food source needed by cranes and 

waterfowl (Krapu et al., 2004).

The Delmarva fox squirrel (Sciurus niger cinereus), which inhabits mature forests of mixed 

hardwoods and pines, may be found adjacent to agricultural areas of the Delmarva Peninsula 

(USFWS, 2011b). The squirrel forages for food in woodlots and openings, such as farm fields, 

with a diet that mainly includes acorns, nuts/seeds of hickory, beech, walnut, and loblolly pine. 

They also feed on tree buds and flowers, fungi, insects, fruit, and seeds in the spring and mature, 

green pine cones in the summer and early fall (USF&WS, 1999). The Louisiana black bear 

(Ursus americanus luteolus), occurring in Louisiana, Mississippi, and Texas (Johnsen et al., 

2005), may occasionally forage on soybean; however, other crops such as corn, sugarcane, and 

winter wheat are preferred by the species (MSU, No Date).

The FDA has concluded its review of Dow’s submittal of safety and nutritional data for DAS68416-4 soybean (US-FDA, 2011b) DAS-44406-6 soybean (US-FDA, 2013a). Dow conducted 

safety evaluations based on Codex Alimentarius Commission procedures to assess any potential 

adverse effects on humans or animals resulting from environmental releases and consumption of 

DAS-68416-4 soybean (DAS, 2010b; FAO, 2009; US-FDA, 2011c) and DAS-44406-6 soybean 

(DAS, 2011a). These safety studies included evaluating protein structure and function, including 

homology searches of the amino acid sequences with comparison to all known allergens and 

toxins, an in vitro digestibility assay of the proteins, an acute oral toxicity feeding study in mice, 

159
and a feeding study in broiler chickens (DAS, 2010b; 2011a; Herman et al., 2011a; Herman et 

al., 2011b; US-FDA, 2011c). DAS-68416-4 soybean and DAS-44406-6 soybean AAD-12, PAT 

and EPSPS proteins were determined to have no amino acid sequence similar to known 

allergens, lacked toxic potential to mammals, and was degraded rapidly and completely in gastric 

fluid (DAS, 2010b; 2011a; US-FDA, 2011c). At this time, FDA considers the consultation on 

DAS-68416-4 soybean and DAS-4406-6 soybean to be complete (US-FDA, 2011a; 2013b). 

APHIS has examined data on the food and feed safety of DAS-68416-4 soybean and DAS44406-6 soybean, evaluating the agronomic and morphological characteristics, including 

compositional and nutritional characteristics, safety evaluations and toxicity tests, as compared 

to a conventional hybrid soybean variety (DAS, 2010b; 2011a). Compositional elements 

compared included moisture, protein, fat, carbohydrates, ash, minerals, dietary fiber, essential 

and non-essential amino acids, fatty acids, vitamins, and anti-nutrients (DAS, 2010b; 2011a; 

Herman et al., 2011b). As discussed in Section 4.2.1, Preferred Alternative – Socioeconomic and 

Human Health, the data collected indicate that the PAT and EPSPS proteins present in DAS44406-6 soybean would be equivalent to those produced in other GE crops that are no longer 

subject to the regulatory requirements of 7 CFR part 340 or the plant pest provisions of the Plant 

Protection Act (USDA, 1996; 2001; 2004; 2005). In addition as previously stated, FDA 

concluded: “food and feed derived from DAS-68416-4 soybean are not materially different in 

composition, safety, and other relevant parameters from soybean-derived food and feed currently 

on the market, and that the GE DAS-68416-4 soybean do not raise issues that would require 

premarket review or approval by FDA (US-FDA, 2011a).” Therefore, the ingestion of the plant 

or plant parts is unlikely to affect threatened and endangered species. Because there is no 

toxicity or allergenicity potential with DAS-68416-4 soybean and DAS-44406-6 soybean, there 

would be no direct or indirect toxicity or allergenicity impacts on animal species that feed on 

soybean or the associated biological food chain of organisms. Consultations with FDA were 

successfully completed for the AAD-12, and PAT proteins, which demonstrated a lack of toxicity 

and allergenicity of DAS-68416-4 soybean for human and animal consumption (US-FDA, 

2011a). Therefore, based on these analyses, APHIS concludes that, although unlikely, 

consumption of DAS-68416-4 soybean and DAS-44406-6 soybean plant parts (seeds, leaves, 

stems, pollen, or roots) would have no effect on any listed threatened or endangered animal 

species or animal species proposed for listing.

APHIS considered the possibility that DAS-68416-4 soybean and DAS-44406-6 soybean could 

serve as host plants for a threatened or endangered species (i.e., a listed insect or other organism 

that may use the soybean plant to complete its lifecycle). A review of the species list reveals that 

there are no members of the genus Glycine that serve as a host plant for any threatened or 

endangered species (USFWS, 2014c)

Combining the above information, cultivation of DAS-68416-4 soybean and DAS-44406-6 

soybean and their progeny are expected to have no effect on threatened or endangered animals or 

those proposed for listing.

7.2.3 Summary

After reviewing the possible effects of allowing the environmental release of DAS-68416-4 

soybean and DAS-44406-6 soybean, APHIS has not identified any stressor that could affect the 

160
reproduction, numbers, or distribution of a listed TES or species proposed for listing. APHIS 

also considered the potential effect of a determination of nonregulated status of DAS-68416-4 

soybean and DAS-44406-6 soybean on designated critical habitat or habitat proposed for 

designation, and could identify no differences from effects that would occur from the production 

of other soybean varieties. Soybean is not considered a particularly competitive plant species and 

has been selected for domestication and cultivation under conditions not normally found in 

natural settings (US-EPA, 2010a). Soybean is not sexually compatible with, or serves as a host 

species for, any listed species or species proposed for listing. Consumption of DAS-68416-4 

soybean and DAS-44406-6 soybean by any listed species or species proposed for listing will not 

result in a toxic or allergic reaction. Based on these factors, APHIS has concluded that a 

determination of nonregulated status of DAS-68416-4 soybean and DAS-44406-6 soybean, and 

the corresponding environmental release of these soybean varieties will have no effect on listed 

species or species proposed for listing, and would not affect designated habitat or habitat 

proposed for designation. Because of this no-effect determination, consultation under Section 

7(a)(2) of the Act or the concurrences of the USFWS or NMFS is not required.

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8 CONSIDERATION OF EXECUTIVE ORDERS, STANDARDS, AND 

TREATIES RELATING TO ENVIRONMENTAL IMPACTS

8.1 Executive Orders with Domestic Implications

The following executive orders require consideration of the potential impacts of the Federal 

action to various segments of the population.

• Executive Order (EO) 12898 (US-NARA, 2010), "Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income Populations,"

requires Federal agencies to conduct their programs, policies, and activities that 

substantially affect human health or the environment in a manner so as not to exclude 

persons and populations from participation in or benefiting from such programs. It also 

enforces existing statutes to prevent minority and low-income communities from being 

subjected to disproportionately high and adverse human health or environmental effects. 

• EO 13045, “Protection of Children from Environmental Health Risks and Safety 

Risks,” acknowledges that children may suffer disproportionately from environmental 

health and safety risks because of their developmental stage, greater metabolic activity 

levels, and behavior patterns, as compared to adults. The EO (to the extent permitted by 

law and consistent with the Agency’s mission) requires each Federal agency to identify, 

assess, and address environmental health risks and safety risks that may 

disproportionately affect children.

The No Action and Preferred Alternatives were analyzed with respect to EO 12898 and EO 

13045. APHIS anticipates no potential disproportionate adverse impacts to minority, lowincome, and Tribal populations, and children as a result of this deregulation because the Enlist 

crops are agronomically, phenotypically, and biochemically comparable to conventional corn 

and soybean grown, marketed, and consumed except for the inserted proteins AAD-1, AAD-12, 

PAT, and m2EPSPS proteins. Additionally, none of the Alternatives are expected to have a 

disproportionate adverse effect on minority, low-income, and Tribal populations, or children, as 

a result of this deregulation because of, but not limited to, the appropriate use of personal 

protective equipment and product use in accordance with product label instructions, which are 

expected to prevent any adverse human health impacts associated with increased use of 

herbicides.

FDA completed new protein consultations with Dow on the AAD-1 and AAD-12 proteins on 

May 19, 2010 (US-FDA, 2010a; c). FDA biotechnology consultations with Dow were completed 

on DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean (US-FDA, 2010b; c; 

2011b; c; 2013a; b). As part of the evaluations for these events, FDA reviewed the safety and 

nutritional assessments submitted by Dow concluding that food and feed derived from DAS40278-9 corn, DAS-68416-4 soybean, and DAS-44406-06 soybean are not materially different in 

composition, safety, and other relevant parameters from corn- and soybean-derived food and 

feed currently on the market. 

Dow conducted compositional analyses to establish the nutritional adequacy of forage- and 

grain-derived products from DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-06 

soybean in comparison to conventional counterparts. The studies compared data on key nutrients, 

162
secondary metabolites, and antinutrients for DAS-40278-9 corn, DAS-68416-4 soybean, and 

DAS-44406-06 soybean forage and grain samples and the conventional variety controls. 

According to Dow, the measured parameters were within the combined literature range for corn 

and soybean and the comparisons indicated no biologically meaningful differences for food and 

feed safety and nutrition (US-FDA, 2011b; c; 2013a).

Both the AAD-1 and AAD-12 proteins were investigated for their potential to be a toxin or 

allergen. Bioinformatics studies confirmed the absence of any biologically significant amino acid 

sequence similarity to known protein toxins or allergens. Digestibility studies demonstrated that 

these proteins would be rapidly degraded following ingestion, similar to other dietary proteins. 

Enzymatic activity of the AAD-1 and AAD-12 proteins was shown to be eliminated under all 

heating conditions (US-FDA, 2011b; c; 2013a). Acute oral mouse toxicity studies were 

performed for the AAD-1 and AAD- 12 proteins, as ingestion represents the most likely route of 

human exposure to these proteins. No clinical signs of toxicity were observed in any of the test

animals.

Dow indicated in their submission to FDA that the PAT protein in DAS-68416-4 soybean and 

DAS-44406-6 soybean was shown to be equivalent to that produced in other transgenic crops 

and previous assessments have shown it is non-toxic to mammals and does not exhibit any 

potential to be allergenic to humans. Biotechnology consultations on soybean lines containing 

the PAT protein were completed on May 15, 1998 (US-FDA, 1998) and also was evaluated as 

part of the consultation on DAS-68416-4 soybean completed in 2011(US-FDA, 2011a) and 

DAS-44406-6 soybean completed in 2013 (US-FDA, 2013a). As with the AAD-1 and AAD-12 

proteins, Dow evaluated the allergenicity of the PAT protein inserted in DAS-68416-4 soybean 

and DAS-44406-6 soybean through bioinformatics analyses. No meaningful homologies to 

known or reputed allergens or toxins were identified. EPA has previously reviewed data on the 

acute toxicity and digestibility of the PAT protein and concluded that there is a reasonable 

certainty that no harm will result from aggregate exposure to the U.S. population, including 

infants and children, to the PAT protein (US-EPA, 1997).

DAS-44406-6 soybean, with the inserted AAD-12, PAT, and m2EPSPS proteins, was evaluated 

by FDA (BNF 133) (US-FDA, 2013a; b). FDA evaluated Dow's submission to determine 

whether DAS-44406-6 soybean raises any safety or regulatory issues with respect to the intended 

modifications or with respect to the food and feed itself. Dow compared the protein sequences of 

AAD-12, 2mEPSPS, and PAT proteins to those of known toxins and allergens. Dow reported

that no significant sequence similarities either to known toxins or to known allergens were 

identified. Dow analyzed the composition of forage and grain from DAS-44406-6 soybean 

(unsprayed or sprayed with up to three herbicides) and compared it with Maverick, the recipient 

line (hereafter referred to as the control), which has the same genetic background as DAS-44406-

6 soybean, but does not contain the DAS-44406-6 event. Summarizing the results of its 

compositional analyses, Dow concluded that the component levels in DAS-44406-6 soybean 

were found to be either statistically indistinguishable from those in the control line, or consistent 

with ranges for soybean in the literature or with a reference line. Consequently, Dow concluded

that there are no unintended compositional differences between DAS-44406-6 soybean and the 

control. Dow also concluded that DAS-44406-6 is comparable to conventional soybean. FDA did 

not identify any issues under the FDCA that would require further evaluation at that time (USFDA, 2013a; b).

163
Taken together, the evidence indicates that the AAD-1, AAD-12, PAT, and m2EPSPS proteins 

are not toxic or not likely to be allergenic to humans. Based on the information submitted by the 

applicant and reviewed by APHIS, DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-

6 soybean are agronomically, phenotypically, and biochemically comparable to conventional 

corn and soybean grown, marketed, and consumed except for the inserted proteins AAD-1, 

AAD-12, PAT, and m2EPSPS proteins. 

Agricultural workers, which may include children, minorities, and low-income populations, 

could come into contact with the deregulated EnlistTM crops being grown. Common agricultural 

practices that would be used with the EnlistTM crops are no different than those utilized on 

current conventional and GE crops. If EPA approves the additional new uses of 2,4-D on DAS40278-9 corn, DAS-68416-4 soybean, and DAS-44406-06 soybean, 2,4-D use patterns on these 

corn and soybean varieties would be different than is currently allowed. As a result, the use of 

2,4-D is expected to increase.

EPA regulates the use of herbicides under FIFRA and is making a separate decision which may 

or may not allow the additional use of 2,4-D on these plants. EPA considers the toxicity of 

pesticides to humans, including sensitive population, such as children, in its pesticide registration

and registration reviews.

Currently, the EPA is proposing to revise the existing Worker Protection Standard (WPS) at 40 

CFR part 170 to reduce the incidence of occupational pesticide exposure and related illness 

among agricultural workers (workers) and pesticide handlers (handlers) covered by the rule. EPA 

is proposing to strengthen the protections provided to agricultural workers and handlers under 

the WPS by improving elements of the existing regulation, such as training, notification, 

communication materials, use of personal protective equipment, and decontamination supplies. 

EPA expects the revisions, once final, to prevent unreasonable adverse effects from exposure to 

pesticides among agricultural workers and pesticide handlers; vulnerable groups, such as 

minority and low-income populations, child farmworkers, and farmworker families; and the 

general public. This regulation, in combination with other components of EPA’s pesticide 

regulatory program, is intended to prevent unreasonable adverse effects of pesticides among 

pesticide applicators, workers, handlers, the general public, and vulnerable groups, such as 

minority and low‐income populations.

The results of available mammalian toxicity studies associated with the AAD-1, AAD-12, 

EPSPS, and PAT proteins establish the safety of DAS-40278-9 corn, DAS-68416-4 soybean, and 

DAS-44406-6 soybean and associated products to humans, including minorities, low-income 

populations, and children who might be exposed to them through agricultural production and/or 

processing. No additional safety precautions would need to be taken with nonregulated DAS40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean. Based on these factors, a 

determination of nonregulated status to DAS-40278-9 corn, DAS-68416-4 soybean, and DAS44406-6 soybean is not expected to have a disproportionate adverse effect on minorities, lowincome and Tribal populations, or children.

Further, the increased cost of seed for HR crops such as EnlistTM relative to conventional seeds is 

not a barrier to low income producers, since net returns for HR soybean and corn were in the 

aggregate no different (Fernandez-Cornejo et al., 2014). Regardless of seed premiums charged 

164
for GE seeds such as EnlistTM, growers select GE herbicide resistant seeds because they are 

associated with certain conveniences in the production of the crop, such simplifying herbicide 

practices and gaining ability to spray herbicides at different times in the developmental stages of 

the crop.

The following executive order addresses Federal responsibilities regarding the introduction and 

effects of invasive species:

EO 1311 (US-NARA, 2010), “Invasive Species,” states that Federal agencies take action 

to prevent the introduction of invasive species, to provide for their control, and to 

minimize the economic, ecological, and human health impacts that invasive species 

cause. 

Neither corn nor soybean is listed in the U.S. as a noxious weed species by the Federal 

government (USDA-NRCS, 2010c), nor are these crops listed as invasive species by major 

invasive plant data bases (GRN, 2012; University of Georgia and USDOI-NPS, 2009). 

While pollen-mediated gene transfer can occur, there are no differences in the potential for gene 

flow and weediness from conventional or other GE varieties. Outcrossing and weediness are 

addressed in the PPRAs (USDA-APHIS, 2010b; 2012a; b)and DAS-40278-9 corn, DAS-68416-4 

soybean, and DAS-44406-6 soybean are similar to other HR-corn or HR-soybean varieties. The 

risk of gene flow and weediness of DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-

6 soybean is no greater than that of other nonregulated, HR corn or soybean varieties.

The following executive order requires the protection of migratory bird populations:

EO 13186 (US-NARA, 2010), “Responsibilities of Federal Agencies to Protect 

Migratory Birds,” states that federal agencies taking actions that have, or are likely to 

have, a measurable negative effect on migratory bird populations are directed to develop 

and implement, within two years, a Memorandum of Understanding (MOU) with the Fish 

and Wildlife Service that shall promote the conservation of migratory bird populations. 

Data submitted by the applicant has shown no substantial difference in compositional and 

nutritional quality of DAS-40278-9 corn compared with other GE corn or non-GE corn, apart 

from the presence of the AAD-1 protein. Similarly, except for the presence of the inserted 

proteins, DAS-68416-4 soybean and DAS-44406-6 soybean have been found to be 

compositionally and nutritionally comparable to other GE soybean or non-GE soybean varieties. 

Additionally, the PAT and EPSPS proteins have been cultivated in a wide variety of commercial 

corn and soybean strains since 1995. The migratory birds that forage in cornfields are unlikely to 

be affected adversely by ingesting DAS-40278-9 corn, DAS-68416-4 soybean, DAS-44406-6 

soybean and associated products.

EPA considers the toxicity of pesticides to birds in its pesticide registration and registration 

reviews.

8.2 International Implications

EO 12114 (US-NARA, 2010), “Environmental Effects Abroad of Major Federal 

Actions” requires federal officials to take into consideration any potential environmental 

165
effects outside the U.S., its territories, and possessions that result from actions being 

taken. 

APHIS has given this EO careful consideration and does not expect a significant environmental 

impact outside the U.S. in the event of a determination of nonregulated status of DAS-40278-9 

corn, DAS-68416-4 soybean, and DAS-44406-6 soybean. All existing national and international 

regulatory authorities and phytosanitary regimes that currently apply to introductions of new 

corn and soybean cultivars internationally apply equally to those covered by an APHIS 

determination of nonregulated status under 7 CFR part 340. 

Any international trade of DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 

soybean subsequent to a determination of nonregulated status of the product would be fully 

subject to national phytosanitary requirements and be in accordance with phytosanitary standards 

developed under the International Plant Protection Convention (IPPC, 2010). The purpose of the 

IPPC “is to secure a common and effective action to prevent the spread and introduction of pests 

of plants and plant products and to promote appropriate measures for their control” (IPPC, 2010). 

The protection it affords extends to natural flora and plant products and includes both direct and 

indirect damage by pests, including weeds. 

The IPPC establishes a standard for the reciprocal acceptance of phytosanitary certification 

among the nations that have signed or acceded to the Convention (172 countries as of March 

2010). In April 2004, a standard for PRA of living modified organisms (LMOs) was adopted at a 

meeting of the governing body of the IPPC as a supplement to an existing standard, International 

Standard for Phytosanitary Measures No. 11 (ISPM-11, Pest Risk Analysis for Quarantine 

Pests). The standard acknowledges that all LMOs will not present a pest risk and that a 

determination needs to be made early in the PRA for importation as to whether the LMO poses a 

potential pest risk resulting from the genetic modification. APHIS pest risk assessment

procedures for GE organisms are consistent with the guidance developed under the IPPC. In 

addition, issues that may relate to commercialization and transboundary movement of particular

agricultural commodities produced through biotechnology are being addressed in other 

international forums and through national regulations.

The Cartagena Protocol on Biosafety is a treaty under the United Nations Convention on 

Biological Diversity (CBD) that established a framework for the safe transboundary movement, 

with respect to the environment and biodiversity, of LMOs, which include those modified 

through biotechnology. The Protocol came into force on September 11, 2003, and 160 countries 

are Parties to it as of December 2010 (CBD, 2010). Although the U.S. is not a party to the CBD, 

and thus not a party to the Cartagena Protocol on Biosafety, U.S. exporters will still need to 

comply with those regulations that importing countries which are Parties to the Protocol have 

promulgated to comply with their obligations. The first intentional transboundary movement of 

LMOs intended for environmental release (field trials or commercial planting) will require 

consent from the importing country under an advanced informed agreement provision, which 

includes a requirement for a risk assessment consistent with Annex III of the Protocol and the 

required documentation.

LMOs imported for food, feed, or processing are exempt from the advanced informed agreement 

procedure and are covered under Article 11 and Annex II of the Protocol. Under Article 11, 

Parties must post decisions to the Biosafety Clearinghouse database on domestic use of LMOs 

166
for food, feed, or processing that may be subject to transboundary movement. To facilitate 

compliance with obligations to this protocol, the U.S. Government has developed a website that 

provides the status of all regulatory reviews completed for different uses of bioengineered 

products (NBII, 2010). These data will be available to the Biosafety Clearinghouse. 

APHIS continues to work toward harmonization of biosafety and biotechnology consensus 

documents, guidelines, and regulations, including within the North American Plant Protection 

Organization (NAPPO), which includes Mexico, Canada, and the U.S., and within the 

Organization for Economic Cooperation and Development (OECD). NAPPO has completed 

three modules of the Regional Standards for Phytosanitary Measures No. 14, Importation and 

Release into the Environment of Transgenic Plants in NAPPO Member Countries (NAPPO, 

2009).

APHIS also participates in the North American Biotechnology Initiative, a forum for information

exchange and cooperation on agricultural biotechnology issues for the U.S., Mexico, and 

Canada. In addition, bilateral discussions on biotechnology regulatory issues are held regularly 

with other countries including Argentina, Brazil, Japan, China, and Korea.

8.3 Compliance with Clean Water Act and Clean Air Act

This EIS evaluated the potential changes in corn and soybean production associated with 

approving the petition for a determination of nonregulated status to DAS-40278-9 corn, DAS68416-4 soybean, and DAS-44406-6 soybean (see Subsection, 4.2.1) and determined that the 

cultivation of DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean would not 

lead to the increase in or expand the area of corn and soybean production that could impact water 

resources or air quality any differently than currently cultivated corn and soybean varieties. The 

herbicide resistance conferred by the genetic modification of DAS-40278-9 corn, DAS-68416-4 

soybean, and DAS-44406-6 soybean is not expected to result in any changes in water usage for 

cultivation compared to current corn and soybean production. Based on these analyses, APHIS 

concludes that an extension of a determination of nonregulated status to DAS-40278-9 corn, 

DAS-68416-4 soybean, and DAS-44406-6 soybean would comply with the CWA and the CAA.

8.4 Impacts on Unique Characteristics of Geographic Areas

Approving the petition for a determination of nonregulated status to DAS-40278-9 corn, DAS68416-4 soybean, and DAS-44406-6 soybean is not expected to impact unique characteristics of 

geographic areas such as parklands, prime farmlands, wetlands, wild and scenic areas, or 

ecologically critical areas.

Dow has presented results of agronomic field trials for DAS-40278-9 corn, DAS-68416-4 

soybean, and DAS-44406-6 soybean that demonstrate there are no differences in agronomic 

practices, between DAS-40278-9 corn and currently available HR-corn varieties or between 

DAS-68416-4 soybean or DAS-44406-6 soybean and currently available HR-soybean varieties. 

The common agricultural practices that would be carried out in the cultivation of DAS-40278-9 

corn, DAS-68416-4 soybean, and DAS-44406-6 soybean are not expected to deviate from 

current practices. The product is expected to be cultivated by growers on agricultural land 

167
currently suitable for production of corn or soybean, and is not anticipated to expand the 

cultivation of corn or soybean to new, natural areas. 

The Preferred Alternative for DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 

soybean does not propose major ground disturbances or new physical destruction or damage to 

property, or any alterations of property, wildlife habitat, or landscapes. Likewise, no prescribed 

sale, lease, or transfer of ownership of any property is expected as a direct result of a 

determination of nonregulated status for DAS-40278-9 corn, DAS-68416-4 soybean, and DAS44406-6 soybean. This action would not convert land use to nonagricultural use and, therefore, 

would have no adverse impact on prime farmland. Standard agricultural practices for land 

preparation, planting, irrigation, and harvesting of plants would be used on agricultural lands 

planted to DAS-40278-9 corn, DAS-68416-4 soybean, and DAS-44406-6 soybean, including the 

use of EPA-registered pesticides. 

As a result of court orders and settlements, an endangered species assessment evaluating the 

potential impacts of the use of glyphosate on the federally threatened California red legged frog 

(CRLF) is underway (US-EPA, 2009c). The EPA has requested initiation of formal consultation 

with the USFWS under Section 7 of the ESA to address the potential effects of glyphosate on the 

CRLF (US-EPA, 2009c). The EPA’s formal consultation request for the California red legged 

frog was based on the potential for direct and indirect effects due to decreases in prey items, as 

well as potential impacts to habitat (See Section 6, Threatened and Endangered Species).

In 2004, the EPA made a “not likely to adversely affect” determination from the use of 

glyphosate on 11 evolutionarily significant units (ESUs) of salmon and steelhead in California 

and an ESU of salmon in southern Oregon (US-EPA, 2004) (see Section 6, Threatened and 

Endangered Species). Formal consultation with the NMFS was initiated by EPA on October 12, 

2004 to fulfill a Consent Decree entered into between EPA and the Californians’ for Alternatives 

to Toxics related to the potential effects of various pesticides used on plants and certain 

threatened and endangered salmon or steelhead species. While this consultation is ongoing, the 

EPA has allowed glyphosate to remain on the market, and it is approved for continued use in 

accordance with all label requirements. Submittals to this analysis can be found at the 

Regulations.gov website under docket designation EPA-HQ-OPP-2009-0361. 

EPA plans to conduct a comprehensive ecological risk assessment, including an endangered 

species assessment, for all uses of glyphosate and its salts (US-EPA, 2009a). Assessments to 

determine impacts on unique geographic areas include:

• An ecological risk assessment to determine whether the use of glyphosate has “no effect” 

or “may affect” federally listed TES or their designated critical habitat; 

• A spray drift buffer zone analysis to evaluate potential exposure reductions to non-target 

aquatic and terrestrial plants.

The information gathered during the ecological and endangered species risk assessment will be 

used by the EPA to make the registration review decision.

Based on these findings, including the assumption that label use restrictions are in place to 

protect unique geographic areas and that those label use restrictions are adhered to, approving the 

petition for a determination of nonregulated status to DAS-40278-9 corn, DAS-68416-4 soybean, 

168
and DAS-44406-6 soybean is not expected to impact unique characteristics of geographic areas 

such as park lands, prime farm lands, wetlands, wild and scenic areas, or ecologically critical 

areas. 

8.5 National Historic Preservation Act (NHPA) of 1966 as Amended

The NHPA of 1966 and its implementing regulations (36 CFR 800) require Federal agencies to:

1) determine whether activities they propose constitute "undertakings" that have the potential to 

cause effects on historic properties; 2) if so, to evaluate the effects of such undertakings on such 

historic resources and consult with the Advisory Council on Historic Preservation (i.e., State 

Historic Preservation Office, Tribal Historic Preservation Officers), as appropriate. 

The APHIS proposed action, a determination of nonregulated status of DAS-40278-9 corn, DAS68416-4 soybean, and DAS-44406-6 soybean is not expected to adversely impact cultural 

resources on tribal properties. Any farming activity that may be taken by farmers on tribal lands 

would only be conducted at the tribe’s request. Thus, the tribes would have control over any 

potential conflict with cultural resources on tribal properties.

The APHIS Preferred Alternative would neither impact districts, sites, highways, structures, or 

objects listed in or eligible for listing in the National Register of Historic Places, nor would it 

likely cause any loss or destruction of significant scientific, cultural, or historical resources. This 

action is limited to a determination of nonregulated status of DAS-40278-9 corn, DAS-68416-4 

soybean, and DAS-44406-6 soybean.

The APHIS proposed action is not an undertaking that may directly or indirectly cause alteration 

in the character or use of historic properties protected under the NHPA. In general, common 

agricultural activities conducted under this action do not have the potential to introduce visual, 

atmospheric, or noise elements to areas in which they are used that could result in effects on the 

character or use of historic properties. For example, there is potential for increased noise on the 

use and enjoyment of a historic property during the operation of tractors and other mechanical 

equipment close to such sites. A built-in mitigating factor for this issue is that virtually all of the 

methods involved would only have temporary effects on the audible nature of a site and can be 

ended at any time to restore the audible qualities of such sites to their original condition with no 

further adverse effects. These cultivation practices are already being conducted throughout the 

corn and soybean production regions. The cultivation of DAS-40278-9 corn, DAS-68416-4 

soybean, and DAS-44406-6 soybean is not expected to change any of these agronomic practices 

that would result in an adverse impact under the NHPA.

169
9 LIST OF PREPARERS

Name, Title, Project 

Function Education and Experience

APHIS

Sidney W. Abel III

Assistant Deputy 

Administrator

Reviewer

 M.S., Environmental Sciences – Chemistry, The George 

Washington University

 B.S., Special Studies – Environmental Chemistry, 

University of Maryland

 25 years of professional experience in developing and 

conducting environmental risk assessments specializing 

in the fate, transport, and effects of physical, chemical, 

and biological substances.

Michael P. Blanchette

Senior Environmental 

Protection Specialist

Threatened and Endangered 

Species Analysis

 B.S., Entomology, University of New Hampshire

 22 years of professional experience as an Environmental 

Protection Specialist

 8 years evaluating plant pest and environmental impacts 

of genetically engineered crops, including effects to 

threatened and endangered species and critical habitat.

Virginia Boulais

Regulatory Biotechnologist

Affected Environment

 M.S. Biotechnology, University of Maryland

 B.S. Cellular Molecular Biology and Genetics, 

University of Maryland

 3 years of professional experience evaluating plant pest

risk and regulatory permitting.

 13 years of professional experience in transgenic crop 

development, plant pathology and molecular biology.

Omar Gardner

Environmental Protection 

Specialist

Affected Environment

Environmental Impacts

 M.S., Environmental Science & Policy, Johns Hopkins 

University.

 B.S., Environmental Science, CUNY Medgar Evers 

College

 1 year of professional experience in environmental risk 

assessment of genetically engineered organisms.

Neil E. Hoffman

Science Advisor

 Ph.D., Plant Physiology, University of California, Davis

 B.S., Plant Biology, Cornell University

 30 years of professional experience in plant biochemistry 

and molecular biology.

 10 years of professional experience in environmental 

risk assessment of genetically engineered organisms.

170
Name, Title, Project 

Function Education and Experience

Alan Pearson

Biotechnologist

Affected Environment

Environmental Impacts

 Ph.D., Biology, Massachusetts Institute of Technology

 B.A., Biochemistry, BranFEIS University

 5 years of professional experience in environmental risk 

assessment of genetically engineered organisms.

 15 years of professional experience in molecular and 

cellular biology.

Craig Roseland

Senior Environmental 

Protection Specialist

Appendices

 Ph.D., Developmental and Cell Biology, University of 

California, Irvine

 B.S., Biological Sciences, University of California, 

Irvine

 11 years of experience in environmental risk assessment

and regulatory analysis.

Diane Sinkowski

Environmental Protection 

Specialist

Affected Environment

Appendices

 M.E., Environmental Engineering Sciences, University 

of Florida

 B.S., Nuclear Engineering Sciences (Health Physics), 

Minor in Environmental Studies, University of Florida

 20 years of professional experience assessing 

environmental impacts, evaluating human and 

environmental exposures, and conducting risk 

assessments.

 9 years of professional experience conducting NEPA

analyses.

 3 years of professional experience in environmental risk 

assessment of genetically engineered organisms.

Anna Smelley

Biotechnologist

 B.S. Biology, University of South Florida

 3 years of professional experience in environmental risk 

assessment of genetically engineered organisms and 

managing and preparing NEPA documents

 8 years of professional experience in mammalian 

pharmacology and toxicology.

171
Name, Title, Project 

Function Education and Experience

Rebecca Stankiewicz Gabel

Supervisory Environmental 

Protection Specialist

 Ph.D., Genetics, University of Connecticut

 M.S., Genetics, University of Connecticut

 B.S., Animal Science, University of Connecticut

 National Environmental Policy Act Certificate Program 

– Nicolas School of the Environment, Duke University

 9 years of professional experience in environmental risk 

assessment of genetically engineered organisms.

 10 years of professional experience in molecular biology 

and genetics, including the development of genetically 

engineered organisms.

Adam Tulu

Environmental Protection 

Specialist

 Ph.D., Environmental Biochemistry, University of 

Maryland

 B.S., Environmental Science, University of Maryland

 4 years of professional experience in biochemistry and 

molecular biology.

 2 years of professional experience in NEPA analyses and 

environmental risk assessment of genetically engineered 

organisms.

Joseph Vorgetts

Senior Environmental 

Protection Specialist

Editor

 Ph.D., Entomology, Clemson University

 M.S., Entomology, Rutgers University

 B.S., Environmental Science, Rutgers University

 13 years of experience in environmental risk assessment

and regulatory development and analysis.

 25 years of experience in insect survey, suppression and 

management with pesticides and biological control 

organisms.

 2 years of professional experience in environmental risk 

assessment of genetically engineered organisms.

172
Name, Title, Project 

Function Education and Experience

Karen Walker

Environmental Protection 

Specialist

Affected Environment 

Environmental Impacts

 Ph.D., Entomology, Virginia Tech

 M.S., Biology, George Mason University

 B.S., Biology, George Mason University

 13 years of experience in environmental risk assessment

and regulatory development and analysis.

 8 years of experience in insect survey and suppression 

management.

 1 year of professional experience in environmental risk 

assessment of genetically engineered organisms.

173
10 DISTRIBUTION LIST FOR 2,4-D EIS

Contacts for EPA Regions:

Mike Stover, PE

US EPA, Region 1

5 Post Office Square, Suite 100

Mail Code OEP06-3

Boston, MA 02109-3912

Grace Musumeci

US EPA, Region 2

290 Broadway

New York, NY 10007-1866

Barbara Rudnick

US EPA, Region 3

1650 Arch Street

Philadelphia, PA 19103-2029

Ntale Kajumba

US EPA, Region 4

Federal Center

61 Forsyth Street, SW

Atlanta, GA 30303-3104

Ken Westlake

US EPA, Region 5

77 West Jackson Boulevard

Chicago, IL 60604-3507

Michael Jansky

US EPA, Region 6

Fountain Place 12th Floor, Suite 1200

1445 Ross Avenue

Dallas, TX 75202-2733

US EPA, Region 7

NEPA Program

11201 Renner Blvd.

Lenexa, KS 66219

Philip Strobel

US EPA, Region 8

1595 Wynkoop St.

Denver, CO 80202-1129

James Munson

US EPA, Region 9

75 Hawthorne Street

San Francisco, CA 94105

Christine Reichgott

US EPA Region 10

1200 Sixth Avenue, Suite 900

Mail Code: ETTA-088

Seattle, WA 98101

____________________________________

David Ortman

7043 22nd Avenue N.W.

Seattle, WA 98117

Whit Lewis

US Fish & Wildlife Service

Region 4, South East

2829 Cypress Creek Road

Linden, TN 37096

Marcia Ishii-Eiteman, PhD

Senior Scientist, Pesticide Action Network

1611 Telegraph Ave.

Suite 1200

Oakland, CA 94612

Food & Water Watch

1616 P Street NW, Suite 300

Washington, DC 20036

Sharon Pratt

Center for Food Safety

660 Pennsylvania Ave.

Suite 302

Washington, DC 20003

174
Steve Smith

Save Our Crops Coalition

ssmith@redgold.com

In addition to this distribution list APHIS notified all of its stakeholders of the availability of the 

EIS for review and comment.

175
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12 INDEX

acreage, 26, 28, 42, 44, 47, 48, 49, 59, 91, 

104, 106, 168

air quality, 23, 26, 32, 42, 102, 103, 104, 

112, 145, 167

alternatives, 1, 17, 57, 59, 76, 77, 80, 85, 90, 

95, 106, 118, 119, 127, 128, 129, 130, 

131, 136, 144, 145

beef production, 60, 83

buffer zones, 62, 168

climate change, 24, 26, 32, 42, 44, 104, 105, 

112, 145

corn, conventional, 14, 63, 87, 165

corn, organic, 62, 63

corn, volunteer, 92, 93, 156

cover crops, 67, 69, 81, 90, 95, 96, 104, 137

critical habitat, 153, 154, 155, 156, 158, 159, 

161, 168, 170

crop rotation, 37, 59, 64, 65, 67, 72, 77, 80, 

81, 95, 96, 119, 135, 137, 138

cross-pollination, 62, 63

cultivation practices, 42, 80, 154, 169

cumulative impacts, 7, 8, 14, 111, 114, 115, 

116, 118, 128, 134, 144, 146, 147

dairy production, 47, 48, 49, 60, 83

economic environment, i, 1, 18, 81, 82, 106, 

107, 117, 166

endangered species, 154, 157, 160, 168, 170

Enlist, vi, 4, 17, 19, 21, 22, 23, 24, 25, 72, 

77, 106, 107, 108, 111, 112, 113, 114, 

115, 117, 118, 133, 134, 138, 139, 140, 

144, 145, 146, 147, 149

environmental consequences, 11, 14, 155

exports, 18, 63, 81, 107

Federal Food, Drug and Cosmetic Act, 6, 

84, 85

Federal Insecticide, Fungicide and 

Rodenticide Act, 5, 6, 79, 87, 91, 106, 

109, 110, 111, 112, 113, 116, 153, 164

food and feed, 18, 25, 26, 84, 85, 91, 108, 

109, 157, 160, 162, 163

Food Quality Protection Act, 6, 99, 111

forage, 43, 48, 54, 55, 67, 68, 84, 89, 90, 

125, 159, 162, 165

gene flow, 158, 165

grazing, 43, 48, 49, 84, 101, 125

greenhouse gases, 24, 42, 43, 104, 105, 145

groundwater, 38, 39, 40, 41, 98, 99, 100, 

102, 111, 116

hay production, 45, 46, 47, 48, 52, 58, 78, 

84, 101

herbicide use, 9, 24, 57, 65, 77, 79, 109, 

110, 111, 128, 132, 134, 139, 144, 146, 

149, 153

human health, 6, 26, 84, 109, 113, 116, 162, 

165

human safety, 80, 87, 91

irrigation, 37, 38, 39, 40, 41, 42, 43, 96, 97, 

98, 99, 100, 101, 102, 104, 149, 168

isolation distances, 13, 14, 62, 63

land use, 26, 28, 42, 44, 47, 48, 49, 59, 91, 

104, 106, 168

National Environmental Policy Act, 1, 7, 8, 

150, 171, 172, 174

National Organic Program, 62, 63

notifications, 86, 112, 113

organic farming, 62

pesticide registration, 86, 91, 110, 164, 165

pesticide tolerance, 6

physical environment, 8, 26, 32

plant diseases, 36, 96

plant pest risk analysis, 1, 8, 9, 117

plant pests, i, vii, 1, 2, 3, 5, 7, 11, 12, 13, 14, 

62, 68, 88, 154, 160, 170

pollination, 62, 63

polymerase chain reaction, 107

production costs, 59

production practices, 26, 42, 62, 90, 104, 

112, 144, 146

registered pesticide, 6, 87, 91, 110, 168

risk assessment, 9, 14, 115, 116, 166, 168, 

170, 171, 172, 173

scoping, 8

seed production, 28, 84

silage, 27, 57, 84

socioeconomic impacts, 7, 115

soil quality, 22, 35, 64, 94, 95, 96, 111, 144

soybean, conventional, 13, 14, 165

soybean, volunteers, 93

spray drift, 99, 104, 111, 168

stewardship, 81, 117, 133, 136

202
tillage practices, 17, 22, 23, 24, 59, 64, 65, 

69, 90, 95, 96, 138, 145, 146, 147

unreasonable adverse effects, 6, 116

water resources, 32, 39, 44, 105, 167

weediness, 67, 154, 155, 156, 158, 159, 165

worker health, 86

worker safety, 26, 72, 109

203