The Ethanol Decade

An Expansion of U.S. Corn 

Production, 2000-09

Steven Wallander

Roger Claassen

Cynthia Nickerson

Economic

Information

Bulletin

Number 79

August 2011

United States 

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Agriculture

Economic

Research

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Recommended citation format for this publication: 

Wallander, Steven, Roger Claassen, and Cynthia Nickerson. The 

Ethanol Decade: An Expansion of U.S. Corn Production, 2000-09, 

EIB-79, U.S. Department of Agriculture, Economic Research Service, 

August 2011.

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United States

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of Agriculture

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A Report from the Economic Research Service

Abstract

The recent 9-billion-gallon increase in corn-based ethanol production, which resulted 

from a combination of rising gasoline prices and a suite of Federal bioenergy policies, provides evidence of how farmers altered their land-use decisions in response to 

increased demand for corn. As some forecasts had suggested, corn acreage increased 

mostly on farms that previously specialized in soybeans. Other farms, however, offset 

this shift by expanding soybean production. Farm-level data reveal that the simultaneous 

net expansion of corn and soybean acreage resulted from a reduction in cotton acreage, a 

shift from uncultivated hay to cropland, and the expansion of double cropping (consecutively producing two crops of either like or unlike commodities on the same land within 

the same year). 

Keywords: Agricultural Resource Management Survey (ARMS), bioenergy, ethanol, 

indirect effects, land use, corn production, environmental impacts

Acknowledgments

The authors thank staff from Economic Research Service: Marca Weinberg, Utpal 

Vasavada, and Keith Fuglie for helpful comment on earlier drafts. We are grateful to 

Ruben Lubowski (Environmental Defense Fund), Bruce Babcock (Iowa State University), 

and Erik Dohlman (ERS) for thoughtful reviews. The authors also thank Bob Dubman 

(ERS) for assisting with access to and analysis of the ARMS data. Since this report 

would not have been possible without a very unique dataset, the authors also would like to 

thank the many staff members at ERS and NASS who made the special bioenergy version 

of the 2008 ARMS a possibility. The authors would also like to thank Angela Anderson 

for her editorial input and Wynnice Pointer-Napper for graphic design support. 

Steven Wallander, swallander@ers.usda.gov

Roger Claassen, classen@ers.usda.gov

Cynthia Nickerson, cnickerson@ers.usda.gov

The Ethanol Decade

An Expansion of U.S. Corn 

Production, 2000-09

Economic 

Information 

Bulletin 

Number 79

August 2011
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Economic Research Service/USDA

Contents

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Relative Importance of Corn Acreage for Corn Expansion. . . . . . . . . . . 3

Aggregate Evidence of the Expansion in Corn Acreage . . . . . . . . . . . . . . 4

Farm-Level Evidence of the Expansion in Corn Acres. . . . . . . . . . . . . . . 8

Changes in Harvested Acres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
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Summary

What Is the Issue?

As annual U.S. ethanol production increased 9 billion gallons between 2000 

and 2009, demand for the feedstock used to produce ethanol also increased. 

In the United States, corn is the primary feedstock for ethanol production, 

and harvested corn acreage increased by roughly 10 percent (7.2 million 

acres) over the same period, with much of the change occurring in 2006-08. 

The environmental and economic implications of such a large shift in land 

use depend largely on where these additional corn acres are located. In this 

study, we analyze data from a special bioenergy survey of farm operators to 

determine, for the fi rst time, how farm-level land-use decisions affected corn 

supplies and competing crops.

What Did the Study Find?

As farmers react to price changes for commodities they can produce on their 

farms, adjustments in land-use decisions can be complex. Not only do landuse decisions by individual farmers refl ect the relative productivity of farmland for specifi c crops, but price expectations can differ from one operator to 

the next and decisions can change from year-to-year as new expectations are 

formed. Increased demand for corn, attributed to bioenergy policies and other 

market conditions during 2000-09, resulted in a complex array of cropping 

pattern changes. 

• Corn production expanded between 2000 and 2009 due partly to an 

increase in corn acreage relative to historic levels and partly to an 

increase in corn yields. 

• Crop acreage shifts at the farm level indicate complex market adjustments 

between 2006 and 2008:

Farms specializing in soybeans in 2006 accounted for most of 

the increase in corn acreage; 

Farms shifting from other crops into soybeans offset the shift 

from soybeans to corn; and

Some farms reduced corn acreage, while other farms expanded 

soybean and corn acreage simultaneously.

• Expanding total acreage in major cultivated crops on corn and soybean 

farms also increased corn and soybean acreage:

The average shift from hay, USDA Conservation Reserve 

Program, or grazing land into cultivated cropland accounted for 

about a third of the average increase in harvested crop acreage, 

mostly from hay; and

Double cropping (consecutively producing two crops of either 

like or unlike commodities on the same land within the same 

year) and a reduction in idled cropland also expanded harvested 

crop acreage.
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How Was the Study Conducted?

This report examines the expansion in U.S. corn production between 2000 

and 2009, but focuses specifi cally on farm-level evidence for 2006-08—a 

period of dramatic corn price increases. Higher corn prices (relative to alternative crop prices) stimulated increased corn production. Analyzing farmlevel survey data allows us to determine the relative scale and sources of 

cropland expansion. The farm-level data were drawn from a special version of 

the 2008 Agricultural Resources Management Survey (ARMS) that sampled 

corn and soybean farmers simultaneously. Corn and soybeans are often 

grown in rotation, so targeting producers of both crops provides a full representation of joint production for both crops. The ARMS is a detailed, annual 

survey of farm businesses and associated households conducted jointly by 

the U.S. Department of Agriculture’s Economic Research Service (ERS) and 

National Agricultural Statistics Service (NASS). We investigated the changes 

in aggregate crop acreages between 2000 and 2009 by using annual crop 

production summaries and the 1997, 2002, and 2007 Agricultural Censuses. 
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Introduction

Between 2000 and 2009, U.S. ethanol production increased from 1.6 billion 

gallons to 10.8 billion gallons (U.S. Department of Energy, 2010). Over the 

same period, U.S. corn production increased from 9.9 billion bushels to 13.1 

billion bushels, while harvested corn increased from 72.4 million acres to 

79.6 million acres (USDA, National Agricultural Statistics Service, 2010).1

This study examines how farms expanded corn acreage during this period, 

primarily between 2006 and 2008, and informs a number of questions about 

the unintended environmental effects of bioenergy policies.

Increasing demand for ethanol (and for corn as an ethanol feedstock) over the 

past decade came in response to a rise in energy prices and Federal bioenergy policies aimed at reducing greenhouse gas emissions, reducing groundlevel ozone and smog, and increasing energy independence.2 Previous studies 

suggest, however, that bioenergy policies may have unintended impacts, 

including those on the environment, the livestock sector, and food prices 

due to increased competition for corn. (See box, “Crop Prices and Ethanol 

Demand,” for a discussion of the changes in corn and other crop prices 

between 2000 and 2009.) Potential environmental impacts include the loss of 

wildlife habitat, greater carbon emissions, increased local air pollution from 

ethanol production, and reduced water quality (Searchinger et al., 2008; Hill 

et al., 2009; U.S. Environmental Protection Agency, 2010). The magnitude of 

these impacts depends on how and where corn production expansion occurs 

and how farmers adjust production of other crops (Malcolm et al., 2009). 

For example, increased conversion of hay or pasture to crop production or 

increased double-cropped acreage3 and the use of more inputs may accelerate nutrient runoff and soil erosion. Even shifts from relatively low-input 

crops to high-input crops (e.g., wheat to corn) could affect environmental 

quality. When acreage shifts from one high-input crop to another (e.g., cotton 

to corn), however, ethanol-induced changes may be negligible or could even 

reduce environmental externalities.

1Harvested acres are used as a measure of land committed to corn rather 

than planted acres because the latter 

includes corn planted for silage.

2The Renewable Fuel Standard and 

ethanol production tax credits seek to 

replace a portion of gasoline consumption with ethanol consumption. The 

Clean Air Act requires the addition of 

oxygenates to fuel in some areas of the 

country to reduce ground-level ozone 

and smog. Ethanol is currently the 

preferred oxygenate in most regions of 

the country, particularly since MTBE 

(methyl tertiary butyl ether), the previously preferred oxygenate, has been 

identifi ed as a drinking water pollutant.

3The practice of consecutively 

producing two crops of either like or 

unlike commodities on the same land 

within the same year.
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The changes in corn production described in this report are not only a response 

to domestic bioenergy policies but also to other market forces and Government 

policies. According to the Congressional Budget Offi ce (CBO) (2009), about 20 

percent of the increase in corn prices between 2007 and 2008 was due to domestic 

ethanol demand. The CBO report also cites research by the International Food 

Policy Research Institute (IFPRI) that 40 percent of the rise in corn prices between 

2000 and 2007 was due to global ethanol demand. Other factors infl uencing corn 

prices included energy prices, exchange rates, and adverse weather. Recent changes 

in the corn market allow us to examine how corn production has expanded. As 

shown in the price series below, corn price increases since 2006 were accompanied 

by a price increase for soybeans and wheat, but cotton prices have not increased as 

dramatically. Since farmers react to price trends when making land-use decisions, 

these price trends infl uence the pathways the farm sector has taken as it adjusted to 

increased demand for corn for ethanol production.

Crop Prices and Ethanol Demand

Relative changes in major crop prices

Monthly crop price index (January 2006 = 1)

Source: USDA, National Agricultural Statistics Service, 

http://www.nass.usda.gov/Charts_and_Maps/graphics/data/pitw.txt.

VA

KY

NC

TN

GA

SC

2000 01 02 03 04 05 06 07 08 09

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Corn Soybeans Wheat Cotton
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Relative Importance of Corn Acreage 

for Corn Expansion

Agricultural markets can meet the growing demand for corn-based 

ethanol by: 

1. Diverting corn from other uses, such as exports, food production, and 

livestock feed; 

2. Increasing corn yields (bushels per acre); or 

3. Increasing the amount of land planted to corn. 

Corn acreage could be increased by reducing acreage in other crops, bringing 

new acreage into crop production, or expanding double-cropping practices. 

All of these changes occurred in response to ethanol production increases 

over the past decade.

Non-ethanol uses of corn have not increased over the past decade, as greater 

ethanol production has captured a larger share of corn production. The use of 

distillers’ grains (a by-product of ethanol production) as livestock feed may 

have reduced demand for corn, but even with this substitution, some corn 

was diverted from other uses. Between 2000 and 2009, corn used for ethanol 

increased by 3.7 billion bushels, while total corn production increased by 3.2 

billion bushels (fi g. 1). 

Corn yield increases have not kept up with ethanol production growth. 

Current agricultural projections show corn yield increasing at about 2 

bushels per acre per year, which is almost the same rate that corn yield 

increased nationally between 2000 and 2009 (USDA, Economic Research 

Service, 2010). If corn acreage had been maintained at the 72.4 million acres 

harvested in 2000, then yield increases of 2 bushels per acre per year would 

have provided for only an additional 1.3 billion bushels of corn—below the 

amount needed to fuel expanding production of ethanol.4 

4From the perspective of indirect 

effects, this reliance on “maintained” 

acreage (in conjunction with yield increases) is as relevant to the analysis of 

bioenergy policies as any potential reliance on “expanded” corn acreage relative to historic trends. Distinguishing 

between “maintained” and “expanded” 

corn acreage is useful, however, since 

each may have different environmental 

impacts.

Figure 1

Primary uses of U.S. corn

Billion bushels of corn

Notes: Corn used for ethanol was not tracked separately prior to 1980. Corn used for the 

“food, seed, and other” category was split between several categories prior to 1980.

Source: USDA, Economic Research Service Feed Grains Database.

1975 78 81 84 87 90 93 96 99 2002 05 08

0

1

2

3

4

5

6

7

Ethanol

Food, seed, and other

Livestock feed and residual

Exports
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Aggregate Evidence of the Expansion 

in Corn Acreage

Crop acreage adjustments ultimately occur at the fi eld level as farmers decide 

whether to plant a particular crop on each piece of land in a given year. Often 

farmers make multiyear planting decisions and plant crops in rotation. One of 

the most common rotations sees corn and soybeans planted in alternating years 

on the same fi eld, which makes shifting to more intensive corn rotations (e.g., a 

3-year rotation of corn-corn-soy) a plausible adjustment to higher corn demand.5 

Most crop acreage data are available only at an aggregated level (national, 

State, or county). In this section, we compare aggregate data (national, State, 

and county) with predictions from previous simulation studies. The aggregate 

data show that reducing soybean acreage is not the only option to expand corn 

acreage. Our farm-level analysis, presented in the next section, demonstrates 

how net acreage changes in aggregate data resulted from farm-level decisions. 

Most simulation studies of bioenergy policies predicted large increases in 

corn acreage as ethanol production increased. The studies differ signifi cantly, 

however, in the sources of those acreage increases (table 1). For two different 

scenarios, Searchinger et al. (2008) predicted that increases in domestic 

(U.S.) corn acreage would come predominately from reducing soybean 

and wheat acreage, as well as from increasing cropland acreage. The U.S. 

Environmental Protection Agency (EPA) (2010) predicted that increases in 

corn acreage would come from reducing soybean acreage and increasing 

cropland. In contrast, Malcolm et al. (2009) predicted that increases in corn 

and soybean acreage would come primarily from reducing idled cropland.

Observed changes are never a perfect test of simulation study predictions, 

which generally compare simulated outcomes with a simulated (and calibrated) baseline scenario. Observed changes may differ from those previously 

predicted because of the range of ethanol expansion under consideration, 

unexpected changes in related markets (e.g., fertilizer), or differences 

between shortrun and longrun adjustments. Nonetheless, the increase in 

ethanol demand over the past decade was precisely the type of demand-side 

shock that these simulation studies sought to model.

National acreage shifted out of soybeans and into corn between 2006 and 

2007, but soybean acreage rebounded between 2007 and 2008 (fi g. 2). Over 

the long run, however, both corn and soybean acreage have been expanding 

without an obvious historical shift out of soybeans and into corn.6 In 

general, corn and soybean acreage expanded over both the long and short 

run (table 2), whereas most other crop acreage decreased over the long run, 

suggesting that acreage responses to greater corn demand do not mimic 

acreage responses predicted by simulation studies. 

Regional differences in soybean acreage changes may explain why national 

soybean acreage did not decrease over this period. Several States in the Corn 

Belt and Lake State regions—most notably Iowa, Illinois, and Minnesota—

show large increases in corn acreage with proportional decreases in soybean 

acreage (fi g. 3). Other States—most notably South Dakota, Kansas, Mississippi, 

and Arkansas—show large increases in both corn and soybean acreage.

5Most regions of the country see substantial benefi ts from joint production 

of corn and soybeans. Corn production 

is nutrient intensive, whereas soybeans 

fi x nitrogen in the soil. As a result, 

rotating corn and soybeans can reduce 

fertilizer costs. In addition, rotating 

corn and soybeans can reduce pesticide 

application costs by reducing the 

chance of pests and diseases becoming 

established.

6In the absence of bioenergy policies 

promoting the production of cornbased ethanol, soybean acreage might 

have been substantially higher. In 

such a case, the actual shift away from 

soybean acreage is simply obscured 

by increases in soybean demand that 

are unrelated to bioenergy policy. This 

would require a rapid increase in soybean demand that occurred simultaneously with the rapid increase in ethanol 

demand since 2006.
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Table 1

Comparing simulation studies of corn ethanol expansion

Study Searchinger et al. Searchinger et al. Malcolm et al. EPA RFS2 RIA 

(FASOM)

EPA RFS2 RIA 

(FAPRI-CARD)

Year modeled 2016/17 2016/17 2015 2022 2022

Billion gallons

Increase in ethanol

14.77 

(from 14.75 

to 29.52)

8.08 

(from 14.75 

to 22.84)

1.7 

(from 13.30 

to 15.00)

2.7 corn-based 

(from 12.3 to 15.00)

plus 13.5 cellulosic

2.7 corn-based 

(from 12.3 to 15.00) 

plus small change 

in imported ethanol

Predicted change in land-use/cropping selection

Million acres

Predicted increase 

in corn acres 19.4 10.0 3.2 3.6 1.8 

Predicted increase 

in cropland 5.5 2.9 4.9 8.1 0.7 

Other major 

predicted increases Soybeans (1.9)

Switchgrass 

(12.5)

Major predicted 

decreases

Soybeans

(-9.6) 

Wheat 

(-4.8)

Soybeans 

(-4.1)

Wheat 

(-3.3)

Rice and 

sorghum 

(each -0.1)

Wheat (-2.9)

Soybeans (-1.4) 

Barley (-1.2) 

Rice and hay 

(each -0.8) 

Oats and cotton 

(each -0.2)

Soybeans 

(-0.7)

EPA=U.S. Environmental Protection Agency.

RFS2=Renewable Fuel Standard Program.

RIA=Regulatory Impact Analysis.

FASOM=Forest and Agricultural Sector Optimization Model.

FAPRI-CARD=Food and Agricultural Policy Research Institute-Center for Agricultural and Rural Development.

Source: Searchinger et al., 2008; Malcolm et al., 2009; U.S. Environmental Protection Agency, 2010.

Figure 2

Harvested acreage for major U.S. crops

Millions of acres

Source: USDA, National Agricultural Statistics Service Crop Production Summaries.

2000 01 02 03 04 05 06 07 08 09

0

20

40

60

80

100

Corn for grain Cotton upland Hay, all (dry)

Oats Sorghum for grain Soybeans

Wheat, all Wheat, other spring Wheat, winter all
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Table 2

National changes in harvested acreage, by crop

Change in acreage

Crop 2006-08 2000-09

Million acres

Corn (grain) 7.93 7.13 

Soybeans 0.08 3.93 

Cotton (upland) (5.01) (5.49)

Corn (silage) (0.61) (2.58)

Wheat (winter) 8.50 (0.97)

Wheat (durum) 0.76 (1.17)

Wheat (spring, other) (0.36) (1.55)

Hay (alfalfa, dry) 0.19 (2.61)

Hay (other, dry) 0.21 6.30 

Oats (0.17) (1.09)

Sorghum (grain) 2.33 (2.25)

Total 13.86 (0.34)

Note: Numbers in parentheses indicate decreases.

Source: USDA, National Agricultural Statistics Service Crop Production Summaries.

Figure 3

State-level changes in corn and soybean acreage, 2006-08

Change in soybean acres harvested (thousands)

-1,000

-800

-600

-400

-200

0

200

400

-200 0 200 400 600 800 1,000 1,200 1,400

Change in corn acres harvested (thousands)

IL

IA

NE

SD

MN IN

ND

KS

OH MO

MS

TX

WI

LA

AR

MI

KY

TN NC

GA

CO

AL

CA

SC

NY VA

OK

Source: USDA, National Agricultural Statistics Service Crop Production Summaries.
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Regional differences are also apparent in how farms expand total harvested 

acreage (fi g. 4). Expanding harvested acreage was an important trend in 

the Northern and Southern Plains, as well as in the lower Mississippi River 

Valley. Aggregate data sources do not provide detail on how harvested 

acreage might have expanded, including conversion of previously uncultivated 

or fallowed land to cultivated cropland or the expansion of double cropping. 

For that, we turn to farm-level data.

Figure 4

County-level changes in harvested acres of corn for grain, soybeans, 

wheat, sorghum, cotton, barley, and alfalfa, 2006-08

Notes: Each crop contributed to the sum of harvested acreage if nonmissing acreage was reported 

in the county in both 2006 and 2008. For a few counties, this means that a given crop’s 

acreage was excluded from the sum of harvested acreage when it was reported at the 

county level in one year but was not reported in the other year.

Source: USDA, Economic Research Service calculations based on USDA, National 

Agricultural Statistics Service Crop Production Summaries.

Change in acres from 2006 to 2008

25,001 - 140,300

5,001 - 25,000

-4,999 - 5,000

-9,999 - -5,000

-89,200 - -10,000
8

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Farm-Level Evidence of the Expansion 

in Corn Acres

Farm-level data reveal important differences in how various types of farms 

expanded corn production. These data may explain why aggregate national 

data do not show a net movement out of soybeans and why county-level 

data show an increase in total harvested acreage in some regions. The data 

were derived from a special bioenergy version of the Agricultural Resources 

Management Survey (ARMS), in which corn and soybean farmers reported 

on acreage and the crops they planted over the 2006-08 period (see box, 

“Background on the Data: 2008 ARMS”). 

Farm-level data reveal adjustments in crop acreage between 2006 and 2008. 

About a third of the farms growing corn and soybeans in 2008 harvested 

more corn acreage in 2008 than in 2006. A fourth of the farms growing corn 

and soybeans in 2008 harvested less corn acreage in 2008 than in 2006.7 To 

capture the impact of movement into and out of corn (as well as into and out 

of other crops), we investigated changes for different categories of farms. 

Due to the focus on movement into corn acreage and how ARMS selected 

farms for survey, our study identifi es farms according to the dominant crop 

among noncorn acreage (table 3). (See box “Farm Classifi cations” for details 

on the farm classifi cation scheme.) If corn acreage is coming primarily from 

soybean acreage, as predicted by some simulation studies, then soybean 

farms will account for most of the growth in corn production. Alternatively, 

if corn acreage is coming primarily from an expansion of cropland, then the 

growth in corn production may be more evenly spread across all types of 

farms or more concentrated among farms with land in forage production. 

Both market adjustments and normal crop rotations can infl uence how we 

observe farm-level changes in acreage. To reduce the infl uence of normal 

crop rotations on observed land-use decisions, we focus on net acreage 

changes over the entire 2-year period (2006-08). By comparing 2006 acreage 

with 2008 acreage, we reduce the chance of mistaking planned rotations 

for market adjustments. For example, consider a farm that grows only corn 

and soybeans, practices corn/soybean year-on-year rotations on every fi eld, 

and has 4 out of 10 equal-sized fi elds (40 percent of total acreage) in corn in 

2006. We would expect that farm, without any market adjustments, to have 

60 percent of its acreage in corn in 2007 before returning to 40 percent of its 

acreage in corn in 2008. Year-on-year changes in acreage would refl ect rotations, whereas 2006-08 changes in acreage would refl ect market adjustments. 

Year-on-year rotations and continuous production are the most common 

forms of joint production of corn and soybeans, although a full treatment of 

rotations introduces uncertainty into a farmers’ crop rotation selection (e.g., 

Livingston et al., 2008). 

The contribution of each farm type to increased corn acreage is the total change 

in corn acreage for that type of farm (a weighted sum of the change in acreage) 

divided by the total change in corn acreage for all farms (a weighted sum of 

the change in acreage) times 100. These percentages use the ARMS sampling 

weights, which refl ect the share of all farms growing corn and soybean represented by each farm type (table 3). Corn farms did not contribute, on average, 

7The ARMS sampling for the phase 

3 questionnaire targets farms that grew 

the desired crops in 2008. These statistics do not represent farms that grew 

no corn or soybeans in 2008, including 

those that grew one or both crops in 

2006 or 2007. This approach to sampling, therefore, accurately captures the 

movement into corn and soybeans, but 

may understate movement out of corn 

and soybeans.
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to corn acreage expansion because they reduced corn acreage between 2006 

and 2008. Over half (53.2 percent) of the corn acreage expansion came from 

soybean farms. The remaining increase in corn acreage is split almost evenly 

between the other farm types. Nonetheless, cotton farms played a disproportionate role in expanding corn acreage. Cotton farms in 2006 made up less than 

1 percent of the ARMS sample but were responsible for more than 12 percent 

of the increase in both corn and soybean acreage. 

The 2006 corn farms were the largest source (42.3 percent) of expanded 

soybean acreage between 2006 and 2008 (table 3). Cotton farms accounted 

for a signifi cant portion of soybean acreage expansion (12.2 percent) despite 

being a small part of the sample. “Other” farms played a larger role in 

soybean acreage expansion than in corn acreage expansion. In contrast, wheat 

farms contributed more to corn acreage than to soybean acreage. 

Attributing corn and/or soybean acreage growth to a decrease in a farm’s 

dominant crop acreage is supported by the fact that observed reductions 

The USDA’s National Agricultural Statistics Service and Economic Research 

Service annually conduct the Agricultural Resource Management Survey (ARMS) 

to obtain information on farming practices and production costs. Each year, a 

portion of the survey targets specifi c crops or livestock commodities. The 2008 

ARMS incorporated several innovations that provided an unprecedented source of 

data on farm-level changes in corn production:

• The bioenergy version of the 2008 ARMS simultaneously sampled corn and 

soybean farmers. Since these two crops are often grown in rotation, targeting 

producers of both crops provided a full representation of how farms vary in the 

joint production of corn and soybeans.

• The 2008 ARMS also included questions about production practices in 2006 

and 2007, particularly with respect to crop acreage. Responses provided a 

measure of within-farm variation in corn production over time.

Background on the Data: 2008 ARMS Survey

Farms were categorized according to their dominant crop in 2006. In keeping with 

the standard defi nition of a dominant crop, “corn” farms had at least 50 percent of 

their 2006 harvested acreage in corn. Among other farms, the goal is to identify 

which crop represents the most likely source for new corn acres. Among noncorn 

farms, a dominant crop was therefore defi ned as a plurality of at least 33 percent 

of noncorn harvested acres in 2006. Thus “soybean” farms harvested at least 33 

percent of noncorn acreage in soybeans and more soybeans than any other noncorn 

crop. “Cotton” farms harvested at least 33 percent of 2006 noncorn acreage in 

cotton, and “wheat” farms harvested at least 33 percent in wheat. For “hay” farms, 

alfalfa and other hay were treated as a single crop category. “Other” crop farms 

harvested either sorghum, barley and oats (combined), or “other” as their dominant 

crop or were highly diversifi ed and did not harvest a single crop that constituted at 

least 33 percent of their noncorn acres.

Farm Classifi cations 
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Table 3

Average farm-level changes in crop acreage, 2006-08

Farm type (based on 2006 harvested acreage)

Item

More than 

50 percent of 

acres in corn

Less than 50 percent of acres in corn and 

more than 33 percent of noncorn acres in

Soybeans Wheat Cotton Hay (all) Other

Acres

Average farm size:

 Harvested in 2008 546.4 577.5 918.9 1,683.5 208.4 566.2

 Operated in 2008 637.4 660.8 1,489.5 2,267.8 508.4 794.1

Percent

Contributions to expansion:

 Sampled population 25.7 37.0 4.9 0.6 24.2 7.6

 Share of growth in corn acres * 53.2 13.4 12.5 10.8 10.1

 Share of growth in soy acres 42.3 7.6 5.5 12.2 9.2 23.1

Acres

Average change in acres per farm:

2006 to 2007

 Change in corn grain -8.4c 30.3a 16.4c 196.6a 0.9d 21.8b

 Change in soybeans 10.8b -22.2a 13.2c 55.4b 2.3c 5.6c

2007 to 2008

 Change in corn grain 0.8d -16.6a 9.5d -12.4d 3.3c -9.1d

 Change in soybeans 10.0b 24.8a 0.8d 182.1a 2.5c 32.7b

2006 to 2008

 Change in corn grain -7.6d 13.8b 25.9b 184.3a 4.3c 12.7b

 Change in soybeans 20.7a 2.6d 14.0c 237.5a 4.8b 38.2b

 Change in wheat 9.2b 9.5a -19.4d 93.7b 2.0c 52.8c

 Change in cotton -0.1d -1.5b -0.4d -487.7a -0.2d -1.6c

 Change in hay 2.2b 2.7b 4.6c 0.0d -6.3c 6.3c

 Change in alfalfa 1.4b 0.0d 14.4d 3.0d -4.2c 1.5d

 Change in sorghum 1.5b 0.7d 20.1d 36.7b 0.2d -19.9b

 Change in barley/oats 0.3d 0.2d 11.7d N/A -0.2d -5.0d

 Change in corn silage 1.5b -0.5d -0.6d 6.7d 1.7c -4.6c

 Change in other crop 4.5b 5.4a 20.7d 39.1c 8.9a -32.3c

Change in harvested acres 33.6a 32.0a 73.2b 113.1c 10.4b 29.5d

a Coeffi cient of variation less than or equal to 25.

b Coeffi cient of variation greater than 25 but less than or equal to 50.

c Coeffi cient of variation great than 50 but less than or equal to 75. 

d Coeffi cient of variation great than 75.

* The average corn farm did not contribute at all to the increase in corn acreage.

Notes: New operations (farms that had no harvested acreage in either 2006 or 2007 accounted for about 10 percent of the sample) are 

excluded from the calculations of these averages since they had no data for 2006 acreage to calculate changes in acreage. Values in gray 

are not statistically different from zero. 

Source: USDA, Economic Research Service calculations based on the bioenergy version of the 2008 Agricultural Resource Management 

Survey conducted by National Agricultural Statistics Service and Economic Research Service.

0.9d

0.8d 9.5d -12.4d -9.1d

0.8d

-7.6d

2.6d

-19.4d

-0.4d -0.1d

0.0d

0.7d

0.2d

-0.5d

0.3d

14.4d

20.1d

11.7d

-0.6d

20.7d

0.0d

3.0d

6.7d

0.2d

-0.2d

1.5d

-5.0d

29.5d
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in acreage are consistent with farm classifi cations (i.e., the largest average 

reduction in wheat acres is for wheat farms). For each farm type, the average 

change in total harvested acres is often larger than the average shift into both 

corn and soybeans (table 3). This is not the case for cotton farms. While 

the data show that 2008 corn and soybean farms signifi cantly expanded 

harvested acreage between 2006 and 2008, the data also suggest that these 

farms did not exhaust opportunities for onfarm expansion of harvested 

acreage. The average farm operated more acres than it harvested and, in some 

cases, much more acreage.

Overall, farm-level averages indicate that movement from soybean acreage 

to corn acreage is offset by other movement into soybean acres. The new 

soybean acreage appear to be coming from corn, cotton, sorghum, and other 

crops, as well as from expansion in total harvested acreage. 
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Changes in Harvested Acres

Farm-level data also provide insight into how total harvested acreage 

expanded: 

• By cultivating land previously either idled or uncultivated (e.g., pasture); 

• By expanding double cropping; or 

• By consolidating (adding additional acreage by purchasing or leasing 

surrounding farms).

In the 2008 ARMS, farm operators were asked directly about expanding 

cropland into previously uncultivated acreage. About 16 percent of 2008 

corn and soybean farms brought new acreage into production between 2006 

and 2008. The uncultivated land brought into production by these farms 

accounted for approximately 30 percent of the average farm’s expansion in 

total harvested acreage. Most acreage conversion came from uncultivated 

hay. Approximately 2.5 million acres of CRP land left the program in 2007, 

however, only a small portion of corn and soybean farms (about 2 percent) in 

2008 brought CRP acreage into production between 2006 and 2008 (USDA, 

Farm Service Agency, 2007).8

Although the 2008 ARMS did not ask explicitly about double cropping, the 

extent of this practice can be inferred from the data. In 2008, about 14.6 

percent of corn and soybean farms reported more harvested acreage (when 

summed across all crops) than total land that could be “considered cropland.”9 Farms with harvested acreage larger than cropland acreage (i.e., farms 

inferred to be double cropping in 2008) also had a much higher rate of expansion in harvested acreage than other farms.10

Data from the 2007 Agricultural Census and annual NASS crop production 

summaries reveal that an estimated 12 million acres were double cropped 

in 2008, an increase of about 4 million acres since 2006. For this study, 

we estimated the total amount of double-cropped acreage in each region in 

census years (1997, 2002, and 2007) by taking the difference between total 

harvested acreage for all crops and age the reported “harvested acreage,” or 

any acreage on which at least one crop was harvested.11 To estimate the total 

double-cropped acreage in 2006 and 2008, we assumed that changes in total 

double cropping in 2007 were proportional to changes in soybean double 

cropping (table 4). The amount of land double cropped has fl uctuated over 

time, ranging from an estimated 11.2 million acres in 1997 and 6.9 million 

acres in 2005 to 12 million acres in 2008. Between 4 and 5 million acres of 

soybean are typically double cropped (and typically follow winter wheat), but 

patterns were atypical during 2005-08. After a low of about 2.5 million acres 

in 2005, double-cropped soybean acreage increased to 3.7 million acres in 

2006 and to 7.2 million acres in 2008.12

Soybeans tend not to be double cropped in some major soy-producing States, 

such as Iowa, Minnesota, the Dakotas, and Nebraska, partly due to shorter 

growing seasons. Double cropping soybeans expanded over 2006-08 in 

almost every State where farmers used the practice. About a third of additional double cropping occurred in Appalachian States and another third 

8For farmers making acreage decisions at the beginning of 2006, the potential for conversion from CRP to crop 

production was considerably larger than 

the number of actual expiring contracts 

indicates. Before the re-enrollment and 

extension of contracts during 2006, 

contracts on over 16 million acres of 

CRP land were due to expire in 2007. 

(See Conservation Reserve Program 

Summary and Enrollment Statistics 

FY 2007 available online: http://www.

fsa.usda.gov/Internet/FSA_File/annual_consv_2007.pdf .)

9The survey does not allow for comparable calculations in 2006 and 2007. 

The question about total land that can 

be “considered cropland” in 2006 and 

2007 was not asked in the survey.

10Double-cropping farms expanded 

harvested acreage between 2006 and 

2008 an average of 87.8 acres versus an 

average of 19.6 acres for other farms. 

Excluding those farms that reduced 

harvested acreage raises average expansion of harvested acreage to 128.2 

acres for double-cropping farms and 

47.4 acres for other farms.

11Annual estimates of doublecropped soybean acreage are available 

for selected States through the NASS 

crop production summaries.

12Based on USDA-NASS unoffi cial 

estimates of soybeans planted following 

another crop in 23 States. The surveyed 

States included those where double 

cropping has historically been more than 

trivial. See http://usda.mannlib.cornell.

edu/usda/nass/Acre//2000s/2009/Acre06-30-2009.pdf.
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in Delta States. Tracking the expansion of double cropping in areas where 

soybeans are not the spring crop is more diffi cult due to data limitations. 

Regional estimates show that double cropping other crops is prevalent in 

some regions where soybean double cropping is limited, particularly in the 

Northern Plains and the Mountain States, and among a few regions where 

double cropping has expanded since 1997 (table 4). 

Beyond increases in cropland or double cropping, harvested acreage growth 

at the farm level could also represent an increase in average farm size due to 

consolidation. This growth represents an inherent diffi culty with farm-level 

data across multiple periods because farms that exit due to consolidation may 

be missed. Analysis of USDA county-level crop production summary data, 

for which farm consolidation is not a problem, confi rms that an increase in 

harvested corn acreage (2006-08) is positively associated with an increase 

in the sum of harvested acreage for major crops. While some uncertainty 

remains about the relative importance of cropland expansion versus doublecropping expansion, our analysis shows that harvested acreage expansion was 

an important source of growth in corn production.

Table 4

U.S. double cropping estimates, by region

Region

Double cropping (all crops) Soybeans double cropped

1997 2002 2007 2006 2007 2008 2009

Thousand acres

Northeast 1,047 481 501 276 375 379 394

Lake States 972 334 396 * * * *

Corn Belt 2,119 1,715 1,788 1,344 1,344 1,670 1,363

Northern 

Plains 1,831 1,976 1,980 347 398 561 185

Appalachian 1,765 1,556 1,402 1,063 1,398 2,216 1,590

Southeast 723 481 585 233 422 717 572

Delta States 1,106 821 995 375 995 1,403 510

Southern 

Plains 583 498 561 62 122 232 224

Mountain 456 211 779****

Pacifi c 618 443 881****

Far West 33 -- 1 * * * *

United States 11,253 8,516 9,868 3,699 5,053 7,177 4,837 

* States where insignifi cant acreages of soybeans are double cropped were not included in the 

survey.

-- = Data not available.

Sources: USDA, Economic Research Service calculations based on NASS Census of 

Agriculture, Annual Crop Production Summaries, and estimates of soybean acreage planted 

following another crop.
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Conclusions

U.S. corn production has increased dramatically over the past decade. 

Until 2006, corn production increases were largely due to increases in corn 

yields. Since 2006, corn production expansion resulted from increases in 

corn acreage.

Our fi ndings partially support previous predictions about the indirect impacts 

of bioenergy policies; the largest source for new corn acreage was farms 

that grew primarily soybeans in 2006. However, there has not been a net 

decrease in soybean acreage. Reduced acreage of other crops and increased 

harvested acreage have been important sources for the simultaneous expansion of corn and soybean production. Several sources for corn (and soybean) 

acreage expansion—increases in double cropping, conversion of uncultivated 

hay, and reductions in cotton acreage—could have unintended consequences 

that differ from those suggested by earlier simulation studies. In addition, 

since observed patterns in both aggregate crop acreage data and farm-level 

land-use decisions refl ect relative crop prices during the study period, future 

farm-sector and farm-level adjustments to increased ethanol production could 

differ from those reported here. For example, recent increases in cotton and 

wheat prices may mean that land-use decisions for the 2011 planting season 

will result in cropping patterns not observed in 2008.
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