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FY2012 Annual Report 

National Program 212 – Climate Change, Soils, and Air Emissions

Introduction

National Program (NP) 212, Climate Change, Soils and Emissions Research supports research to 

improve the quality of atmosphere and soil resources that both affect and are affected by 

agriculture, to understand the effects of climate change on agriculture, and to prepare agriculture 

for adaptation to climate change. 

Agricultural systems function within the soil-atmosphere continuum. Mass and energy exchange 

processes occur within this continuum and agriculture can significantly affect the processes. 

Emissions from agriculture to the atmosphere affect air quality and increase atmospheric 

greenhouse gas (GHG) concentrations. While GHG emissions result from the natural cycling of 

carbon (C) and nitrogen (N), these emissions also contribute to climate change. A changing 

climate impacts agriculture, range and pasture systems, and soils through alterations in 

precipitation and temperature patterns, and increased atmospheric carbon dioxide (CO2) 

concentration. The impacts of climate change create challenges to agriculture and its soil 

resources, but also offer new opportunities for agricultural production and enhancement of soil 

quality. 

Soils are a crucial boundary resource between agriculture and the atmosphere. Soils in 

agricultural systems must be managed to meet rising global demands for food, feed, fiber, fuel 

and ecosystem services while maintaining soil productivity and limiting undesirable interactions 

between soils and the atmosphere. 

The variability of the atmosphere, soils, and plants, and the complexity of interactions among 

these systems require collaborations by ARS scientists conducting NP212 research. Formal and 

informal Cross Location Research (CLR) projects including the Greenhouse gas Reduction 

through Agricultural Carbon Enhancement network (GRACEnet), the Renewable Energy 

Assessment Project (REAP), and field campaigns focused on air quality are successful examples. 

Synthesis and integration of information, including sources outside NP212, by CLR projects 

increases the utility and impact of ARS research. Efficient assimilation of data from NP212 

projects into existing and future collaborative data bases will enhance synthesis and integration 

analyses and expand research opportunities.

ENABLE IMPROVEMENTS OF AIR QUALITY VIA MANAGEMENT AND MITIGATION OF EMISSIONS 

FROM AGRICULTURAL OPERATIONS

Atmospheric emissions from agriculture are under increased scrutiny due to potential negative 

environmental effects and threats to human and animal welfare. Emissions contribute to tensions 

between agriculture and residential communities from visibility impairment (haze) and nuisance 

odors. Major classes of emissions include particulate matter (PM), volatile inorganic compounds 

(primarily ammonia and hydrogen sulfide), volatile organic compounds (VOCs), and those from 

pesticides. Often these emissions exist as mixtures and, thus, adjustments to production practices 
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for abatement may decrease the release of one material while changing the emission character or 

magnitude of other materials.

The Chief of the USDA-Natural Resources Conservation Service convenes the Agricultural Air 

Quality Task Force (AAQTF), a Federal Advisory Committee that meets twice a year. ARS 

participates in the AAQTF via an agency seat, and via invited presentations from scientists. The 

AAQTF is a valuable source of information on stakeholder needs and concerns that provide 

criteria for decisions about agricultural air quality research conducted by ARS.

Selected Accomplishments

Sensitivity of herbicide volatilization to soil moisture. Efficient herbicide application has been 

hampered by a lack of understanding of fate and transport mechanisms. Field investigations 

over the past 14 years by ARS scientists from Beltsville, Maryland, Ames, Iowa and Riverside, 

California have determined that volatilization (vapor loss to the atmosphere) appears to be the 

most critical pathway for herbicide loss from production fields into neighboring ecosystems. 

Herbicide volatilization experiments conducted in Beltsville, Maryland, the longest record of 

herbicide vapor loss observations worldwide, demonstrated that herbicide volatilization is 

greatest under warm, wet soil moisture conditions during the day when air near the soil has a 

tendency to rise as the soil warms. Consequently, all herbicide volatilization models must be 

revised to account for atmospheric stability and soil moisture conditions. The addition of these 

terms significantly improves herbicide volatilization models used to help guide herbicide 

applications on crop fields world-wide. These model improvements have uses in herbicide 

application practices, as well as USDA and U.S. Environmental Protection Agency policy 

development, and they show ways to reduce environmental and economic losses incurred with 

volatilization. 

Volatilization moves pesticides through the air into South Florida ecosystems. The health of 

south Florida ecosystems has been declining due to nutrient and pesticide losses from 

agricultural activities and urban encroachment. The high humidity and temperatures, frequent 

rainfall and irrigation, soil type, and soil structure enhance the loss of applied pesticides to the 

atmosphere for this area. ARS researchers from Beltsville, Maryland and Tifton, Georgia, in 

collaboration with researchers from the University of Florida, examined the fate of endosulfan, 

an insecticide previously identified as a potential hazard to aquatic organisms of this region. 

They discovered that volatilization from the fields, and not drift during application, was by far 

the most likely emission source to nearby Everglades and Biscayne National Parks. This 

discovery provides scientists, regulators, extension specialists, and producers information needed 

to modify agricultural management practices to protect sensitive ecosystems. 

Accurate prediction of pest control and emissions of soil fumigants to the atmosphere. Soil 

fumigants are an important tool for pest control but are also potential atmospheric pollutants. 

Improved application methods are needed to ensure crop protection while minimizing fumigant 

losses to the atmosphere. ARS scientists at the U.S. Salinity Laboratory in Riverside, California 

developed a predictive model that can be used to simultaneously estimate the efficacy of soilborne pest control and fumigant emissions from field soil. The model provides a new decision 

support tool for optimizing fumigant application that ensures adequate crop protection while 
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reducing effects on the environment and concomitant economic impact associated with chemical 

losses.

DEVELOP KNOWLEDGE AND TECHNOLOGIES FOR REDUCING ATMOSPHERIC GREENHOUSE 

GAS CONCENTRATIONS THROUGH MANAGEMENT OF AGRICULTURAL EMISSIONS AND CARBON 

SEQUESTRATION

Agriculture GHG emissions to the atmosphere are among the documented anthropogenic factors 

driving climate change. Land management practices may be altered to reduce GHG emissions. 

Agriculture also provides an opportunity to sequester C in soils, thus offsetting GHG emissions 

and offering a partial solution to slowing the forces of climate change.

ARS conducts the Greenhouse gas Reductions through Agricultural Carbon Enhancement 

network (GRACEnet) project to focus its GHG and carbon sequestration research. The primary 

objective of GRACEnet is to identify and further develop agricultural practices that will enhance 

carbon sequestration in soils, promote sustainability and provide a sound scientific basis for 

carbon credits and trading programs. This program generates information concerning carbon 

storage in agricultural systems that is needed by producers, program managers and policy makers. 

GRACEnet also addresses the other greenhouse gases, nitrous oxide and methane that may be 

emitted by agricultural practices. Agricultural studies by GRACEnet scientists include both 

grazing lands (range and pasture) and crop lands (irrigated and dryland). Coordinated multilocation field studies follow standardized protocols to compare net GHG emissions (carbon 

dioxide, nitrous oxide, methane), carbon sequestration, and broad environmental benefits under 

different management systems including those that a) typify existing production practices, b) 

maximize C sequestration, c) minimize net GHG emissions, and d) meet sustainable production 

and broad environmental benefit goals (including C sequestration, net GHG emissions, water, air 

and soil quality, etc.).

Selected Accomplishments

Major greenhouse gas book published. Concurrent efforts to mitigate agricultural 

contributions to climate change while adapting to its projected consequences will be essential to 

ensure long-term sustainability and food security in the U.S. To facilitate successful responses to 

climate change, USDA-ARS scientists involved in GRACEnet (Greenhouse Gas through 

Agricultural Carbon Enhancement Network) published a book documenting recent research 

accomplishments addressing strategies to mitigate and adapt to climate change. The book, 

entitled Managing Agricultural Greenhouse Gases: Coordinated Agricultural Research through 

GRACEnet to Address our Changing Climate, includes regional syntheses of soil organic carbon 

and GHG dynamics for broad portfolio of agricultural land uses, as well as additional chapters 

central to GRACEnet activities (e.g., modeling, method development, economic outcomes of 

GHG mitigation options, adaptation research, and international collaboration). The book 

supports ARS’s goal of providing knowledge and information on soil carbon sequestration, GHG 

emissions, and environmental benefits to better implement scientifically-based agricultural 

management practices from field to national policy scales.

Agriculture greenhouse gas synthesis document produced. The Council for Agricultural 

Science and Technology (CAST) Task Force Report #141 entitled, "Carbon Sequestration and 

Greenhouse Gas Fluxes in Agriculture: Challenges and Opportunities," was developed by a team 
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of 21 leading scientists under the chairmanship of scientists from ARS and Colorado State 

University. Globally, agriculture accounts for 13.5% of GHG emissions. In the United States, 

agriculture is a small but significant component of the country’s and world’s GHG emissions. 

This report examines the current science to inform the public and policymakers about this crucial 

topic. This report’s primary focus is on agriculture’s role in the land-atmosphere exchanges of 

GHGs as well as agriculture’s ability to decrease GHG emissions or sequester additional carbon 

in agricultural soils while continuing to supply the necessary food, feed, and fiber required for 

the world’s growing population. Practices are outlined for which increased C sequestration and 

decreased emissions of GHGs have been established or, in some instances, are presently under 

investigation. The practices are evaluated and presented in separate sections that cover annual 

cropland, pasture and range, horticultural crops, agroforestry systems, wetlands and organic soils, 

confined livestock, and biofuel feedstock production. Data and analysis from the ARS 

GRACEnet project are frequently cited by the report. The document serves as a statement of the 

state-of-the-art on GHG emissions from agriculture and is thus a significant source of 

information for scientists and policy-makers. 

Deeper application of fertilizer in soil reduces greenhouse gas emissions when used with noor reduced-tillage. A major GHG source from cropping systems is nitrous oxide (N2O) - a byproduct of fertilizer use- that is 300 times more effective than CO2 as a GHG. No tillage (NT) 

and reduced tillage (RT) are increasingly employed to increase soil carbon storage, decrease soil 

CO2 emissions, conserve moisture and reduce erosion, but the effects of NT and RT on N2O 

emissions have been inconsistent among studies performed to date. A global meta-analysis of 

239 direct comparisons of GHG emissions from Conventional Till (CT) and NT/RT was 

performed by scientists from ARS in St. Paul, Minnesota, the University of California-Davis and 

Northern Arizona University. In studies where N fertilizer was initially placed 5 cm or deeper in 

the soil, N2O emissions tended to be 25% lower with NT/RT than with CT, especially in humid 

climates. In contrast, when N fertilizers were placed closer to the soil surface, N2O emissions 

tended to be greater or no different with NT/RT than with CT. These results provide a simple 

means of optimizing tillage and fertilizer management practices to reduce N2O and CO2 GHG 

emissions, while maintaining the other benefits of NT/RT tillage. 

ENABLE AGRICULTURE TO ADAPT TO CLIMATE CHANGE

Mechanisms for adapting to climate change are critical for continued agricultural production and 

stewardship of natural resources. An understanding of the impacts of climate change on natural 

and managed ecosystems provides insights needed to formulate strategies for addressing 

vulnerabilities and exploiting potentially beneficial aspects of climate change. Mechanisms for 

identifying and detecting indicators of impacts are key to formulating management responses. 

Adaptive responses to climate change must be evaluated for impacts on ecosystem function and 

potential feedbacks on the climate system and subsequent consequences for sustainability and 

reinforcement, or offset of, climate change mitigation strategies.

ARS is co-leading the distributed research collaboration entitled the Agricultural Model 

Intercomparison and improvement Project, (AgMIP). The goals of AgMIP are to improve 

substantially the characterization of risk of hunger and world food security due to climate change 

and to enhance adaptation capacity in both developing and developed countries. The project 
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brings together domestic and international crop modelers to advance crop modeling for specific 

crops, collect new field data where needed, and build shared data bases for model development 

and testing. The crop modelers also engage the climate modeling community to enable 

projections of the future crop yields under different climate scenarios.

 

Selected Accomplishments

Soil organic matter in grasslands is susceptible to climate change. Soil organic matter 

(SOM) contributes substantially to the health of rangeland ecosystems. There is a need to 

understand the long term effects of rising atmospheric carbon dioxide (CO2) and warmer 

temperatures associated with climate change on SOM and rangeland plant production. ARS 

scientists in Cheyenne, Wyoming/Fort Collins, Colorado and collaborators from the University 

of Wyoming, and the University of Sydney, Australia subjected portions of a mixed-grass 

prairie to temperature and CO2 concentrations projected for the next 50 years. Plant production 

frequently increased with additional CO2 and warmer temperatures. However, SOM that is 

typically resistant to decomposition also increased, thus indicating the potential for a decline in 

soil quality and health of the rangeland ecosystem. These results suggest that rising CO2 and 

temperature may increase plant production in this semiarid rangeland ecosystem, with an 

associated decrease of SOM and long term rangeland ecosystem health. 

Larger rainfall events associated with climate change may reduce semiarid rangeland 

forage quality. The size of individual rain events in semi-arid rangelands can be as important as 

total annual rainfall in controlling the production and quality of forage for livestock. Nitrogen 

uptake by plants and soil microbes is important for production and quality of forage. Because 

shifts toward larger rainfall events are predicted with climate change, ARS researchers in 

Cheyenne, Wyoming/Fort Collins, Colorado and collaborators from Colorado State University 

studied how different sized rainfall events affected the uptake of soil nutrients by grass roots and 

by soil microbes in the shortgrass steppe of eastern Colorado. Results showed that rainfall event 

size (0.4 or 0.8 inches) did not affect the timing of nitrogen uptake, but did substantially 

influence whether plants or microbes were more effective in acquiring nitrogen. Plants were 

most effective in acquiring nitrogen following smaller rainfall events, whereas soil microbes 

were more effective in acquiring nitrogen following larger rainfall events. Large rainfall events 

result in more efficient use of water by grasses, and therefore increase the efficiency of forage 

production. In contrast, smaller rainfall events may be important for plant nitrogen uptake which 

should maintain high protein concentrations in forage grasses. The findings indicate that 

predicted shifts toward larger rainfall events with future climate change may increase forage 

production but decrease forage quality in semiarid rangelands, thus creating a need for 

supplemental nutrition strategies to maintain livestock production quality.

Elevated atmospheric CO2 selectively affects the vigor of non-native plants. For some plants, 

greater atmospheric CO2 promotes larger and more vigorous growth, and while this can increase 

crop yield, it can also foster an undesired, aggressive spread of non-native plants. Lantana and 

Vinca, non-native species introduced to the U.S. as ornamentals, were grown in Auburn, AL 

under elevated CO2 by ARS researchers. However, Lantana was more responsive to elevated 

CO2 than Vinca. Thus, Vinca is less likely to aggressively spread as atmospheric CO2 increases, 

whereas Lantana will likely respond to additional atmospheric CO2 and may require greater 

effort to control. This study illustrates how non-native species, previously cultivated as noninvasive, have the potential to become invasive as atmospheric CO2 continues to rise. 
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Identification of plants that may create management problems under future climate provides a 

climate change adaptation tool for avoiding unintended consequences of using and/or importing 

non-native species. 

MAINTAINING AND ENHANCING SOIL RESOURCES

Soil productivity must be enhanced to meet increasing global food, feed, fiber, and fuel demands. 

Soil degradation through erosion and decreased physical (e.g., structure, compaction, infiltration), 

chemical (e.g., acidification, salinization, nutrient depletion), and biological (e.g., biodiversity, 

nutrient cycling, soil organic matter) properties and processes must be mitigated to ensure critical 

goods and services provided by soil resources are maintained.

ARS scientists are conducting the Renewable Energy Assessment Project (REAP) to build tools 

that will enable producers to harvest crop residue for biofuel or forage, while maintaining 

sustainable soils. Products from this work are 1) guidelines for management practices supporting 

sustainable harvest of residue, 2) algorithm(s) estimating the amount of crop residue that can be 

sustainably harvested, and 3) decision support tools and guidelines describing the economic 

trade-off between residue harvest and retention to sequester soil. Delivery of this knowledge and 

these products to farmers and the biomass ethanol industry will promote harvest of stover and 

crop residues in a manner that preserves the capacity our soil to produce food, feed, fiber, and 

fuel. 

Selected Accomplishments

Guidelines for corn stover harvest that maintain soil sustainability. Corn stover (crop 

residue left on fields following harvest), has been identified as a potential feedstock for 

producing bioenergy and/or other bioproducts. However, excessive harvest of corn stover may 

also rob the soil of nutrients and carbon need to maintain healthy, sustainable soil, and thus 

guidelines for sustainable corn stover harvest are needed. Four years of cooperative field 

research among ARS scientists in Ames, Iowa, the advanced fuels commercial partnership 

POET-DSM, and Iowa State University showed that to sustain soil carbon levels and other 

critical soil functions, corn stover should not be harvested from a field if the average grain yields 

of the field are less than 11 Mg/ha (175 bu/acre). This information is a key development of ARS 

Renewable Energy Assessment Project (REAP) team studies and provides a guideline for 

enabling the U.S. to reach goals for increased bioenergy and bioproduct production from corn 

stover, while sustaining soil health for future harvests. 

Narrow-row planting reduces sediment and herbicide losses from cotton production 

systems. Changing production practices can improve surface water quality of agricultural lands 

by reducing runoff containing sediment and agrochemicals. ARS scientists at Stoneville, 

Mississippi, evaluated sediment and herbicide losses from 4- to 6-leaf cotton planted in narrow 

and wide rows to determine if a change of row spacing could maintain yields while reducing 

cultivation impacts on water quality. Planting cotton on flat beds with rows spaced 15-inches 

apart reduced sediment loss by 38% relative to the losses from cotton planted on raised beds 

spaced 38-inches apart. Planting cotton in narrow rows also reduced herbicide loss relative to 

that of wide-row systems given similar factors affecting pesticide movement and runoff. 
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Converting from wide-to narrow-row cotton cultivation provides a simple means of reducing 

sediment losses from fields without a reduction of yields, and thus positively impacting MidSouth water quality. 

Reduced tillage in dryland cropping systems improves soil quality in less than 10 years. 

Soil quality indexes are useful metrics of the effects of cover crops and tillage practices on soil 

and water conservation, and are thus valuable indicators of sustainable soil management needed 

for a productive and environmentally safe food supply. ARS scientists at Lubbock, Texas

measured the effects of tillage, and adding diverse grains and cover crops to dryland cropping 

systems on soil quality parameters and water infiltration rates after 8 and 10 years of production. 

Overall, the indexes showed that soil properties were more sensitive to cropping system 

differences (adding more biomass to a cotton crop rotation was found to improve soil quality), 

than tillage differences (conventional versus no tillage), and demonstrated the importance of crop 

rotations for improving soil quality of dryland cropping systems. Although soil microbial 

properties were not sensitive to tillage practices, measurements related to soil quality, including 

organic matter content, soil density, wet and dry aggregate stability, and soil strength, showed 

differences of these systems due to tillage. This study demonstrated that reduced tillage practices 

can be used to improve soil quality for agricultural production in less than 10 years for dryland 

cropping systems.)

OTHER ACTIVITIES

ARS personnel of the NP212 program are also contributing to a variety of activities of USDA, 

national and international interest including the National Earth Observations (NEO) strategy and 

the National Climate Assessment (NCA). The NEO strategy is assessing the capacity of existing 

environmental data collection systems (such as satellites and earth surface-based measurement 

networks) to meet the nation’s information needs for decision-making, and to assess future 

information needs that will affect decisions about the next generation of earth observing satellites 

and earth surface data collection systems. 

Scientists contributing to NP212 are also developing data management systems that will provide 

long-term stewardship for research data generated in pursuit of NP212 Action Plan Goals. 

Currently, GRACEnet and REAP have been the focus of this effort.

FUTURE ACTIVITIES

Research conducted for the ARS NP212 Climate Change, Soils and Air Emissions program will 

continue during coming year with an increased emphasis on synthesis of results and preparation 

of technology transfer mechanisms. The program will conduct an assessment of its most recent 

five years of research and begin planning the next five year research agenda. A report will be 

produced summarizing program accomplishments focused on objectives set forth by the 2009-

2013 Action Plan. The report will be reviewed by a panel of non-ARS employees as per ARS 

Office of Scientific Quality Review (OSQR) protocols. The program summary report will be 

posted on-line. 
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Research collaborations are being planned with USDA-APHIS, USDA-NRCS, NASA, NOAA, 

Department of Energy, and Department of Interior among others. There is increasing interest in 

ARS climate change mitigation and adaptation research for agriculture, air quality research data 

and ARS simulation models by domestic and international partners.