Order Code RL33898
Climate Change:
The Role of the U.S. Agriculture Sector
March 6, 2007
Renée Johnson
Analyst in Agricultural Economics
Resources, Science, and Industry Division

Climate Change:
The Role of the U.S. Agriculture Sector
Summary
The agriculture sector is a source of greenhouse gas (GHG) emissions, which
many scientists agree are contributing to observed climate change. Agriculture is also
a “sink” for sequestering carbon, which might offset GHG emissions by capturing
and storing carbon in agricultural soils. The two key types of GHG emissions
associated with agricultural activities are methane (CH ) and nitrous oxide (N O).
4
2
Agricultural sources of CH emissions mostly occur as part of the natural digestive
4
process of animals and manure management at livestock operations; sources of N O
2
emissions are associated with soil management and fertilizer use on croplands. This
report describes these emissions on a carbon-equivalent basis to illustrate
agriculture’s contribution to total national GHG emissions and to contrast emissions
against estimates of sequestered carbon.
Emissions from agricultural activities account for about 6% of all GHG
emissions in the United States. Carbon captured and stored in U.S. agricultural soils
partially offsets these emissions, sequestering about one-tenth of the emissions
generated by the agriculture sector, but less than 1% of all U.S. emissions annually.
Emissions and sinks discussed in this report are those associated with agricultural
production only. Emissions associated with on-farm energy use or with food
processing or distribution, and carbon uptake on forested lands or open areas that
might be affiliated with the farming sector, are outside the scope of this report.
Most land management and farm conservation practices can help reduce GHG
emissions and/or sequester carbon, including land retirement, conservation tillage,
soil management, and manure and livestock feed management, among other
practices. Many of these practices are encouraged under most existing voluntary
federal and state agricultural programs that provide cost-sharing and technical
assistance to farmers. However, uncertainties are associated with implementing these
types of practices depending on site-specific conditions, the type of practice, how
well it is implemented, the length of time practice is undertaken, and available
funding, among other factors. Despite these considerations, the potential to reduce
emissions and sequester carbon on agricultural lands is reportedly much greater than
current rates.
The debate in Congress over whether and how to address possible future climate
change is intensifying. Historically, legislative initiatives have not specifically
focused on emissions reductions in the agriculture sector. Instead, emissions
reductions and carbon uptake are incidental benefits of existing voluntary
conservation programs that provide financial and technical assistance to implement
certain farm management practices, predominantly for other production or
environmental purposes. The pending 2007 farm bill could expand the scope of these
types of initiatives to more broadly encompass the agriculture sector in overall efforts
to address climate change. Policies and incentives that might further encourage
farmers to adopt such practices include expanding cost-sharing and technical
assistance under existing conservation programs, low-cost loans, grants, incentive
payments, and tax credits.

Contents
Agricultural Emissions and Sinks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Source of National Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Agricultural GHG Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Direct GHG Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Other Types of Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Total GHG Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Uncertainty Estimating Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Other Estimated Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Sources of GHG Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Potential for Additional Reductions . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Agricultural Carbon Sinks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Carbon Loss and Uptake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Total Carbon Sequestration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Estimated Emission Offsets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Uncertainty Estimating Carbon Sinks . . . . . . . . . . . . . . . . . . . . . . . . . 10
Potential for Additional Uptake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Per-Unit Value Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Enhancing Carbon Sinks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Mitigation Strategies in the Agriculture Sector . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Conservation Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Federal Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
State Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Climate Change Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Federal Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
State Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Other Programs and Incentives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Considerations for Congress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Appendix: Primer on the Role of the U.S. Agriculture Sector in the Climate Change
Debate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
List of Figures
Figure 1. Agricultural GHG Emissions, Average 2000-2004 . . . . . . . . . . . . . . . . 7
Figure 2. Carbon Sequestration in Agricultural Soils . . . . . . . . . . . . . . . . . . . . . 10
Figure 3. USDA Conservation Spending, FY2005 . . . . . . . . . . . . . . . . . . . . . . . 18
List of Tables
Table 1. Methane (CH ) and Nitrous Oxide (N O) Emissions and
4
2
Carbon Sinks, Agricultural Activities, 1990-2004 . . . . . . . . . . . . . . . . . . . . 5
Table 2. Representative Carbon Sequestration Rates . . . . . . . . . . . . . . . . . . . . . 13
Table 3. Conservation and Land Management Practices . . . . . . . . . . . . . . . . . . . 17

Climate Change:
The Role of the U.S. Agriculture Sector
The debate in Congress over whether and how to address possible future climate
change is intensifying. In the 109th Congress, more than 100 bills, resolutions, and
amendments were introduced specifically addressing climate change. The role of the
U.S. agriculture sector is often included in this debate. Agriculture is a source of
greenhouse gas (GHG) emissions, which many scientists agree are contributing to
observed climate change. Agriculture is also a “sink” for sequestering carbon, which
partly offsets these emissions. Carbon sequestration (the capture and storage of
carbon) in agricultural soils can be an important component of a climate change
mitigation strategy, limiting the release of carbon from the soil to the atmosphere.
Previous legislative initiatives involving the agriculture sector in addressing
climate change have focused on sequestering carbon on agricultural lands, with most
attention given to forestry activities and restoration projects where the potential to
increase uptake and store carbon for long time periods is greatest. Historically, these
legislative initiatives have not specifically focused on emissions reductions in the
agriculture sector. Instead, emissions reductions and carbon uptake might best be
viewed as incidental benefits of existing agricultural conservation programs. Many
of these programs provide financial and technical assistance to voluntarily implement
certain farm conservation and land management practices, predominantly for other
production or environmental purposes.
The anticipated 2007 farm bill debate1 could expand the scope of ongoing
climate change initiatives to more broadly encompass the agriculture sector,
promoting conservation and land management practices that could further reduce
emissions and sequester carbon in the sector. Policies and incentives that might
further encourage farmers to adopt such practices include expanding cost-sharing and
technical assistance under existing conservation programs, expanding existing
research programs and demonstration projects, and expanding access to low-cost
loans, loan guarantees, grants, incentive payments, and income tax credits.
This report is organized in three parts. First, it discusses the extent of GHG
emissions associated with the U.S. agriculture sector, and cites current and potential
estimates for U.S. agricultural soils to sequester carbon and partly offset national
GHG emissions. Second, the report describes the types of land management and farm
conservation practices that can reduce GHG emissions and/or sequester carbon in
agricultural soils, highlighting those practices that are currently promoted under
existing voluntary federal agricultural programs. Third, the report discusses the types
of questions that may be raised regarding the role of the U.S. agriculture sector in the
1 The current omnibus farm bill, the Farm Security and Rural Investment Act of 2002 (P.L.
107-171), and many of its provisions expire in 2007. Hereafter referred to as “farm bill.”

CRS-2
broader climate change debate, and also discusses the role of climate-related issues
(e.g., GHG emissions reductions and carbon sequestration) in the context of farm
program legislation that the 110th Congress may consider. The Appendix provides a
summary primer of the key topics presented in this report.
This report does not address the potential effects of global climate change on
U.S. agricultural production. Such effects may arise because of increased climate
variability and incidence of global environmental hazards, such as drought and/or
flooding, pests, weeds, and diseases, or temperature and precipitation changes that
might cause locational shifts in where and how agricultural crops are produced.2
This report also does not address how ongoing or anticipated initiatives to
promote U.S. bioenergy production may effect efforts to reduce GHG emissions
and/or sequester carbon, such as by promoting more intensive feedstock production
and by encouraging fewer crop rotations and planting area setbacks, which could both
raise emissions and reduce carbon uptake.
Agricultural Emissions and Sinks
Agriculture is a both a source and a sink of greenhouse gases, generating
emissions that enter the atmosphere and removing carbon dioxide (CO ) from the
2
atmosphere through photosynthesis and storing it in vegetation and soils (a process
known as sequestration). Sequestration in farmland soils partially offsets agricultural
emissions. Despite this offset, however, the U.S. agriculture sector remains a net
source of GHG emissions.
Source of National Estimates
Estimates of GHG emissions and sinks for the U.S. agriculture sector presented
in this report are the official U.S. estimates of national GHG emissions and carbon
uptake, as published annually by the U.S. Environmental Protection Agency (EPA)
in its Inventory of U.S. Greenhouse Gas Emissions and Sinks.3 EPA’s Inventory data
reflect annual national emissions by sector and fuel, including estimates for the
agriculture and forestry sectors. EPA’s estimates rely on data and information from
the U.S. Department of Agriculture (USDA), the Department of Energy, the
Department of Transportation, the Department of Defense, and other federal
departments. The EPA-published data are rigorously and openly peer reviewed
through formal interagency and public reviews involving federal, state, and local
government agencies, as well as private and international organizations. For the
agriculture and forestry sectors, USDA publishes a supplement to EPA’s Inventory,
which builds on much of the same data and information, but in some cases provides
a more detailed breakout by individual states and sources.4
2 See CRS Report RL33817, Climate Change: Federal Expenditures, by Jane Leggett.
3 EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2004, April 2006, at
[http://epa.gov/climatechange/emissions/usinventoryreport.html].
4 USDA, U.S. Agriculture and Forestry Greenhouse Gas Inventory: 1990-2001, TB1907,
(continued...)

CRS-3
In this CRS report, emissions from agricultural activities are aggregated in
“carbon-equivalents” and expressed as million metric tons carbon-equivalent
(MMTCE).5 This aggregation is intended to illustrate agriculture’s contribution to
national GHG emissions and to contrast emissions against estimates of sequestered
carbon. Other estimates used in other reports may alternatively be expressed in terms
of equivalent CO units.
2
Agricultural GHG Emissions
Direct GHG Emissions. The types of GHG emissions associated with
agricultural activities are methane (CH ) and nitrous oxide (N O), which are two of
4
2
the key gases that contribute to GHG emissions.6 These gases are significant
contributors to atmospheric warming and have a greater effect warming than the
same mass of CO 7
2.
Agricultural sources of CH emissions mostly occur as part of the natural
4
digestive process of animals and manure management in U.S. livestock operations.
Sources of N O emissions are mostly associated with soil management and
2
commercial fertilizer and manure use on U.S. croplands, as well as production of
nitrogen-fixing crops.8 Emissions of N O from agriculture sources account for about
2
two-thirds of all reported agriculture emissions; emissions of CH account for about
4
one-third of all reported agriculture emissions. Across all economic sectors, the U.S.
agricultural sector was the leading source of N O emissions (72%) and a major
2
source of CH emissions (29%) in 2004.9
4
Other Types of Emissions. Agricultural activities may also emit other
indirect greenhouse gases, such as carbon monoxide, nitrogen oxides, and volatile
4 (...continued)
March 2004, at [http://www.usda.gov/oce/global_change/gg_inventory.htm].
5 Estimates in this report are converted from EPA-reported data expressed as equivalent CO2
units assuming a multiplier of 0.2727 to yield MMTCE. EPA’s data are reported in
teragrams, or million metric tons. “Carbon-equivalents” equate an amount of a GHG to the
amount of carbon that could have a similar impact on global temperature.
6 The principal gases associated with climate change from human activities are CO , CH ,
2
4
N O, and ozone-depleting substances and chlorinated and fluorinated gases, such as
2
hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. See CRS Report RL33849,
Climate Change: Science and Policy Implications, by Jane Leggett; and Intergovernmental
Panel on Climate Change (IPCC), Climate Change 2001, at [http://www.ipcc.ch/pub/
wg1TARtechsum.pdf].
7 IPCC, Climate Change 2001, at [http://www.ipcc.ch/pub/wg1TARtechsum.pdf]; EPA’s
2006 Inventory, Table ES-2. Methane’s ability to trap heat in the atmosphere is 21 times that
of CO ; nitrous oxide is 310 times that of CO (measured over a 100-year period).
2
2
8 USDA, U.S. Agriculture and Forestry Greenhouse Gas Inventory: 1990-2001, TB1907,
Figure 3-6, March 2004, at [http://www.usda.gov/oce/global_change/gg_inventory.htm].
Nitrogen-fixing crops refer to beans, legumes, alfalfa, and non-alfalfa forage crops.
9 EPA’s 2006 Inventory, Table ES-2. Other major CH sources were landfills, natural gas
4
systems, and coal mining. Mobile combustion was the second largest source of N O.
2

CRS-4
organic compounds from field burning of agricultural residues.10 These emissions are
not included in EPA’s annual Inventory estimates because they contribute only
indirectly to climate change by influencing tropospheric ozone, which is a
greenhouse gas. Agricultural activities may also release other types of air emissions,
some of which are regulated under the federal Clean Air Act, including ammonia,
volatile organic compounds, hydrogen sulfide, and particulate matter.11 These types
of emissions are typically not included in proposals to limit GHG emissions.
The sector also emits CO and other gases through its on-farm energy use, for
2
example, through the use of tractors and other farm machinery. These emissions are
generally aggregated along with other transportation and industrial emissions in the
“energy” sources, where they constitute a very small share of the overall total.
Therefore, these emissions are not included in reported estimates for the U.S.
agriculture sector.
Total GHG Emissions. In 2004, GHG emissions from U.S. agricultural
activities totaled 120 MMTCE, expressed in terms of carbon-equivalent units, and
accounted for 6% of the total GHG emissions in the United States (Table 1).
Although the agriculture sector is a leading economic sector contributing to national
GHG emissions, its share of total emissions is a distant second compared to that for
the energy sector. Fossil fuel combustion is the leading source of GHG emissions in
the United States (80%), with the energy sector generating about 86% of annual
emissions across all sectors.12
Recent trends in GHG emissions associated with the U.S. agriculture sector
suggest emissions reductions in recent years. In 2004, emissions from agricultural
activities are lower compared to estimates for 1995 and 2000, and also lower than the
most recent five-year average (Table 1).
Uncertainty Estimating Emissions. EPA’s estimates are based on annual
USDA data on crop production, livestock inventories, and information on
conservation and land management practices in the agriculture sector. Actual
emissions will depend on site-specific factors, including location, climate, soil type,
type of crop or vegetation, planting area, fertilizer and chemical application, tillage
practices, crop rotations and cover crops, livestock type and average weight, feed mix
and amount consumed, waste management practices (e.g., lagoon, slurry, pit, and
drylot systems), and overall farm management. Emissions may vary year to year
depending on actual growing conditions. More detailed information is reported in
EPA’s 2006 Inventory.
10 EPA’s 2006 Inventory, Table 6-2. NO and CO influence the levels of tropospheric
X
ozone, which is both a local pollutant and a GHG (called “indirect” greenhouse gases). Their
contributions cannot be measured by emissions.
11 See CRS Report RL32948, Air Quality Issues and Animal Agriculture: A Primer, by
Claudia Copeland. Particulate emissions may also contribute to climate change, but their
influence is predominantly local, short-term and poorly quantified.
12 Other contributing sources include wood biomass and ethanol use (3%), nonenergy use
of fuel (2%), and landfills (2%); by sector, industrial processes (5%) and waste (3%) are
other main sources of emissions (EPA’s 2006 Inventory, Tables ES-2 and ES-4).

CRS-5
Table 1. Methane (CH ) and Nitrous Oxide (N O) Emissions and
4
2
Carbon Sinks, Agricultural Activities, 1990-2004
Avg.
Source
1990
1995
2000
2004
2000-2004
million metric tons carbon equivalent (MMTCE)
U.S. Agricultural Activities
GHG Emissions (CH and N O)

4
2
Agriculture Soil Management a
72.6
84.0
75.9
71.3
74.2
Enteric Fermentation b
32.2
33.5
31.5
30.7
31.2
Manure management
13.0
14.5
15.2
15.6
15.5
Rice Cultivation
1.9
2.1
2.0
2.1
2.0
Agricultural Residue Burning
0.3
0.3
0.4
0.4
0.3
Subtotal
119.9
134.4
125.0
120.0
123.2
Carbon Sinks
Agricultural Soils
(14.6)
(14.7)
(11.6)
(12.4)
(12.1)
Other
na
na
na
na
na
Subtotal
(14.6)
(14.7)
(11.6)
(12.4)
(12.1)
Net Emissions, Agriculture
105.2
122.8
113.4
107.6
111.1
Attributable CO emissions:c
2
Fossil fuel/mobile combustion
12.7
15.6
13.8
13.9
13.7
%Total Emissions,
Agriculture
d
7.2%
7.6%
6.6%
6.2%
6.5%
%Total Sinks, Agriculture
5.9%
7.0%
5.6%
5.8%
5.8%
%Total Emissions, Forestry
0.1%
0.1%
0.1%
0.1%
0.1%
%Total Sinks, Forestrye
94.1%
93.0%
94.4%
94.2%
94.2%
Total GHG Emissions, All
Sectors
1,665.9
1,768.0
1,904.1
1,929.2
1,899.3
Total Carbon Sinks, All
Sectors
(248.2)
(167.7)
(207.1)
(212.7)
(210.0)
Net Emissions, All Sectors
1,417.7
1,600.3
1,697.0
1,716.5
1,689.3
Source: EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2004, April 2006,
[http://epa.gov/climatechange/emissions/usinventoryreport.html]. Table ES-2, Table 2-13, and Table
6-1. Converted from EPA-reported carbon dioxide equivalent units (CO Eq.) using a multiplier of
2
0.2727 to yield carbon-equivalent, expressed in million metric tons (MMTCE). EPA data are reported
in teragrams (Tg.), which are equivalent to one million metric tons each.
a. N O emissions from soil management and nutrient/chemical applications on croplands.
2
b. CH emissions from ruminant livestock.
4
c. Emissions from fossil fuel/mobile combustion associated with energy use in the U.S. agricultural
sector (excluded from EPA’s reported GHG emissions for agricultural activities).
d. Does not include attributable CO emissions from fossil fuel/mobile combustion.
2
e. Change in forest stocks and carbon uptake from urban trees and landfilled yard trimmings.
Other Estimated Emissions. EPA’s reported emissions for the U.S.
agriculture sector are based on agricultural production only and do not include
emissions associated with on-farm energy use and forestry activities,13 or emissions
associated with food processing or distribution. Although EPA’s GHG estimates for
the U.S. agriculture sector do not include CO emissions from on-farm energy use,
2
estimates of these CO emissions constitute a small share of overall GHG emissions.
2
During the last few years, EPA’s estimates of CO emissions from on-farm fossil fuel
2
13 Land use and forestry activities account for less than 1% of total estimated GHG
emissions in the United States (EPA’s 2006 Inventory, Table ES-4).

CRS-6
and mobile combustion averaged about 14 MMTCE per year14 (Table 1). These
emissions are generally aggregated with emissions for the transportation and
industrial sectors. Even if these emissions were included with other attributed GHG
emissions for the agriculture sector, this would not substantially raise agriculture’s
overall share of total GHG emissions.
Sources of GHG Emissions. EPA’s Inventory estimates of CH and N O
4
2
emissions from agricultural activities are measured across five categories.
! Agriculture soil management: Nitrous oxide emissions from
farmland soils are associated with cropping practices that disturb
soils and increase oxidation, which can release emissions into the
atmosphere. The types of practices that contribute to emissions
releases are fertilization; irrigation; drainage; cultivation/tillage;
shifts in land use; application and/or deposition of livestock manure
and other organic materials on cropland, pastures, and rangelands;
production of nitrogen-fixing crops and forages; retention of crop
residues; and cultivation of soils with high organic content.
! Enteric fermentation: Methane emissions from livestock
operations occur as part of the normal digestive process in ruminant
animals15 and are produced by rumen fermentation in metabolism
and digestion. The extent of such emissions is often associated with
the nutritional content and efficiency of feed utilized by the animal.16
Higher feed effectiveness is associated with lower emissions.
! Manure management: Methane and nitrous oxide emissions
associated with manure management occur when livestock or
poultry manure is stored or treated in systems that promote anaerobic
decomposition, such as lagoons, ponds, tanks, or pits.
! Rice cultivation: Methane emissions from rice fields occur when
fields are flooded and aerobic decomposition of organic material
gradually depletes the oxygen in the soil and floodwater, causing
anaerobic conditions to develop in the soil and methane to be
released.
! Agricultural residue burning: Methane and nitrous oxide
emissions are released by burning residues or biomass.17
The share of GHG emissions for each of these categories is as follows:
agriculture soil management (about 60% of agriculture emissions), enteric
14 EPA’s 2006 Inventory, Table 2-14.
15 Refers to livestock (cattle, sheep, goats, and buffalo) that have a four-chambered stomach.
In the rumen chamber, bacteria breaks down food and degrades methane as a byproduct.
16 R. A. Leng, “Quantitative Ruminant Nutrition — A Green Science,” Australian Journal
of Agricultural Research
, 44: 363-380. Feed efficiency is based on both fermentive
digestion in the rumen and the efficiency of conversion of feed to output (e.,g, milk, meat)
as nutrients are absorbed.
17 Although carbon is released as well, it is predominantly absorbed again within a year as
part of the cropping cycle, and so is assumed to be net zero emissions unless some goes into
long-term soil carbon content.

CRS-7
fermentation (25%), manure management (13%), rice cultivation (2%), and field
burning of agricultural residues (less than 1%). About 60% of agriculture emissions
are associated with the crop sector and about 40% with the livestock sector (Figure
1
).
Potential for Additional Reductions.
There is potential to lower carbon,
methane, and nitrous oxide emissions from U.S. agricultural facilities at both crop
and livestock operations through further adoption of certain conservation and land
management practices. In most cases, such practices may both reduce emissions and
sequester carbon in agricultural soils.
Figure 1. Agricultural GHG Emissions, Average 2000-2004
Manure Mgmt
Manure Mgmt
Rice
(CH4) 9%
(N2O) 4%
Cultivation
(CH4) 2%
Ag Residue
Burning
(CH4 , N2O)
<1%
Enteric
Ag Soil Mgmt
Fermentation
(N2O) 60%
(CH4) 25%
Source: EPA, 2006 Inventory report, April 2006 [http://epa.gov/climatechange/emissions/
usinventoryreport.html].
Improved Soil Management. Options to reduce nitrous oxide emissions
associated with crop production include improved soil management, more efficient
fertilization, and implementing soil erosion controls and conservation practices. In
the past 100 years, intensive agriculture has caused a soil carbon loss of 30%-50%,
mostly through traditional tillage practices.18 In contrast, conservation tillage
practices preserve soil carbon by maintaining a ground cover after planting and by
reducing soil disturbance compared with traditional cultivation, thereby reducing soil
loss and energy use while maintaining crop yields and quality. Practices include no-
till and minimum, mulch, and ridge tillage. Such tillage practices reduce soil
disturbance, which reduces oxidation and the release of carbon into the atmosphere.
Therefore, conservation tillage practices reduce emissions from cultivation and also
enhance carbon sequestration in soils (discussed later in this report). Nearly 40% of
U.S. planted areas are under some type of conservation tillage practices.19
18 D. C. Reicosky, “Environmental Benefits of Soil Carbon Sequestration,” USDA, at
[http://www.dep.state.pa.us/dep/DEPUTATE/Watermgt/wsm/WSM_TAO/InnovTechFor
um/InnovTechForum-IIE-Reicosky.pdf].
19 USDA, “Conservation Tillage Firmly Planted in U.S. Agriculture,” Agricultural Outlook,
March 2001; USDA, “To Plow or Not to Plow? Balancing Slug Populations With
(continued...)

CRS-8
Improved Manure and Feed Management. Methane emissions associated
with livestock production can be reduced through improved manure and feed
management. Improved manure management is mostly associated with installing
certain manure management systems and technologies that trap emissions, such as
an anaerobic digester20 or lagoon covers. Installing such systems generates other
principal environmental benefits. Installing an anaerobic digester to capture
emissions from livestock operations, for example, would also trap other types of air
emissions, including air pollutants such as ammonia, volatile organic compounds,
hydrogen sulfide, nitrogen oxides, and particulate matter that are regulated under the
federal Clean Air Act. Other benefits include improved water quality through reduced
nutrient runoff from farmlands, which may be regulated under the federal Clean
Water Act.21 Many manure management systems also control flies, produce energy,
increase the fertilizer value of any remaining biosolids, and destroy pathogens and
weed seeds.22
Manure management systems, however, can be costly and difficult to maintain,
given the typically high start-up costs and high annual operating costs. For example,
the initial capital cost of an anaerobic digester with energy recovery is between $0.5
million and $1 million at a large-sized dairy operation, and annual operating costs are
about $36,000. Initial capital costs for a digester at a larger hog operation is about
$250,000, with similar operating costs.23 Upfront capital costs tend to be high
because of site-specific conditions at an individual facility, requiring technical and
engineering expertise. Costs will vary depending on site-specific conditions but may
also vary by production region. Costs may be higher in areas with colder
temperatures, where some types of digesters may not be appropriate or may require
an additional heat source, insulation, or energy requirements to maintain constant,
elevated temperatures.24 Energy requirements to keep a digester heated are likely be
lower in warmer climates.
19 (...continued)
Environmental Concerns and Soil Health,” Agricultural Research, October 2004;
Conservation Technology Information Center (CTIC), “Conservation Tillage Facts,” at
[http://www.conservationinformation.org/?action=learningcenter_core4_convotill].
20 An enclosed tank that promotes decomposition using anaerobic conditions and naturally
occurring bacteria, while producing biogas as a byproduct that can be used as energy.
21 See CRS Report RL32948, Air Quality Issues and Animal Agriculture: A Primer; and
CRS Report RL31851, Animal Waste and Water Quality: EPA Regulation of Concentrated
Animal Feeding Operations (CAFOs)
, by Claudia Copeland.
22 R. Pillars, “Farm-based Anaerobic Digesters,” Michigan State University Extension, at
[http://web2.msue.msu.edu/manure/FinalAnearobicDigestionFactsheet.pdf].
23 EPA, Development Document for the Final Revisions to the NPDES Regulation and the
Effluent Guidelines for Concentrated Animal Feeding Operations
, January 2003.
24 C. Henry and R. Koelsch, “What Is an Anaerobic Digester?” University of Nebraska,
Lincoln, at [http://manure.unl.edu/adobe/v7n10_01.pdf]; and Pennsylvania State University,
“Biogas and Anaerobic Digestion,” at [http://www.biogas.psu.edu/]. For optimum operation,
anaerobic digesters must be kept at a constant, elevated temperature, and any rapid changes
in temperature could disrupt bacterial activity.

CRS-9
Incentives are available to assist crop and livestock producers in implementing
practices and installing systems that may reduce GHG emissions. Such incentives
include cost-sharing and also low-interest financing, loan guarantees, and grants, as
well as technical assistance with implementation. Funding for anaerobic digesters at
U.S. livestock operations occurs under various programs under the 2002 farm bill.25
Despite the availability of federal and/or state-level cost-sharing and technical
assistance, adoption of such systems remains low throughout the United States. There
are currently fewer than 100 digester systems in operation at commercial U.S. dairy
and hog farms, affecting well under 1% of all operations nationwide.26
Improved feed strategies may also lower methane emissions at livestock
operations. Such strategies may involve adding supplements and nutrients to animal
diets, substituting forage crops for purchased feed grains, or instituting multi-phase
feeding to improve digestive efficiency. Other options involve engineering genetic
improvements in animals.27 Purchasing feed supplements and more intensely
managing animal nutrition and feeding practices may add additional costs and
management requirements at the farm level.
Agricultural Carbon Sinks
Carbon Loss and Uptake. Agriculture can sequester carbon, which may
offset GHG emissions by capturing and storing carbon in agricultural soils. On
agricultural lands, carbon can enter the soil through roots, litter, harvest residues, and
animal manure, and may be stored primarily as soil organic matter (SOM; see Figure
2
).28 Soils can hold carbon both underground in the root structure and near the soil
surface and in plant biomass. Loss of soil carbon may occur with shifts in land use,
with conventional cultivation (which may increase oxidation), and through soil
erosion. Carbon sequestration in agricultural soils can be an important component of
a climate change mitigation strategy, since the capture and storage of carbon may
limit the release of carbon from the soil to the atmosphere.
Voluntary land retirement programs and programs that convert or restore
grasslands and wetlands promote carbon capture and storage in agricultural soils.
Conservation practices that raise biomass retention in soils and/or reduce soil
disturbance, such as conservation tillage, also promote sequestration.
25 Mostly Section 9006 and Section 6013 of the farm bill (P.L. 107-171), but also under
other farm bill cost-share programs. CRS communication with USDA staff.
26 As of 2005. EPA, AgStar Digest, Winter 2006, at [http://www.epa.gov/agstar/].
27 R. A. Leng, “Quantitative Ruminant Nutrition — A Green Science,” Australian Journal
of Agricultural Research
, 44: 363-380; H. Steinfeld, C. de Haan, and H. Blackburn,
Livestock-Environment Interactions, Issues and Options, chapter 3 (study commissioned by
the Commission of the European Communities, United Nations, and World Bank), at
[http://www.virtualcentre.org/es/dec/toolbox/FAO/Summary/index.htm].
28 U.S. Geological Survey (USGS), “Carbon Sequestration in Soils,” at [http://edcintl.cr.
usgs.gov/carbonoverview.html].


CRS-10
Figure 2. Carbon Sequestration in
Agricultural Soils
Source: USGS, “Carbon Sequestration in Soils,” at
[http://edcintl.cr.usgs.gov/carbonoverview.html].
SOM = Soil organic matter
Total Carbon Sequestration. In 2004, carbon sequestration by agricultural
soils was estimated at 12.4 MMTCE. Compared to estimates for the most recent
five-year average, estimates for 2004 show possible gains in carbon uptake and
storage in recent years. Compared to 1990 and 1995, however, estimated carbon
sequestration in agricultural soils is lower (Table 1).
Estimated Emission Offsets. Carbon sequestration in the U.S. agricultural
sector currently offsets about one-tenth of the carbon-equivalent of reported GHG
emissions generated by the agriculture sector each year. Thus the sector remains a net
source of GHG emissions. Compared to total national GHG emissions from all
sources, carbon sequestration by the agriculture sector offsets less than 1% of total
U.S. emissions annually. It should be noted that these estimates do not include
estimates for the forestry sector, or sequestration activities on forested lands or open
areas that may be affiliated with the agricultural sector. Forests and trees account for
a majority (94%) of all estimated carbon uptake in the United States, mostly through
forest restoration and tree-planting.29 Carbon uptake in soils on U.S. agricultural
lands accounts for the remainder.
Uncertainty Estimating Carbon Sinks. EPA’s Inventory estimates of
carbon uptake in agricultural soils are based on annual data and information on
cropland conversion to permanent pastures and grasslands, reduced summer fallow
areas in semi-dry areas, increased conservation tillage, and increased organic
fertilizer use (e.g, manure) on farmlands, as well as information on adoption rates and
use of certain conservation and land management practices.
However, actual carbon uptake in agricultural soils depends on several site-
specific factors, including location, climate, land history, soil type, type of crop or
vegetation, planting area, tillage practices, crop rotations and cover crops, and farm
29 Estimated from net forest growth, increased forest area, accumulated forest carbon stocks,
growth in urban trees, and also landfilled yard trimmings (EPA’s 2006 Inventory, Table ES-
5). See also CRS Report RL31432, Carbon Sequestration in Forests, by Ross Gorte.

CRS-11
management in implementing certain conservation and land management practices.
Estimates of the amount of carbon sequestered may vary depending on the amount
of site-specific information included in the estimate, as well as on the accounting
procedures and methodology used to make such calculations.
In general, the effectiveness of adopting conservation and land management
practices will depend on the type of practice, how well the practice is implemented,
and also on the length of time a practice is undertaken. For example, time is needed
for a certain conservation practice to take hold and for benefits to accrue, such as
buildup of carbon in soils from implementing conservation tillage or other soil
management techniques, and growing time for cover crops or vegetative buffers. The
overall length of time the practice remains in place is critical, especially regarding the
sequestration benefits that accrue over the time period in which land is retired. In
addition, not all conservation and land management practices are equally effective
or appropriate in all types of physical settings. For example, the use and effectiveness
of conservation tillage practices will vary depending on soil type and moisture
regime, which may discourage some farmers from adopting or continuing this
practice in some areas.
The potential impermanence of conservation and land management practices
raises concerns about the effectiveness and limited storage value of the types of
conservation practices that sequester carbon, given that the amount of carbon stored
depends on the willingness of landowners to adopt or continue to implement a
particular voluntary conservation practice. There are also concerns that the addition
of other conservation practices may not significantly enhance the sequestration
potential of practices that might already be in place.30 This raises questions about the
cost-effectiveness of sequestering carbon on farmlands relative to other climate
change mitigation strategies in other industry sectors. Finally, implementing
conservation practices and installing new technologies may be contingent on
continued cost-sharing and other financial incentives contained in the current farm
bill; programs funded through this legislation help offset the cost to farmers for these
practices and technologies, which some farmers may not be willing to do otherwise.
Potential for Additional Uptake. USDA reports that the potential for carbon
uptake in agricultural soils is much greater than current rates. USDA forecasts that
the amount of carbon sequestered on U.S. agricultural lands will nearly double from
current levels by 2012, adding roughly an additional 11 MMTCE of sequestered
carbon attributable to the sector.31 This additional uptake is expected through
improved soil management (roughly 60%), improved manure and nutrient
management (about 30%), and additional land-retirement sign-ups (about 10%).
30 See, for example, T. A. Butt and B. A. McCarl, “Implications of Carbon Sequestration for
Landowners,” 2005 Journal of the American Society of Farm Managers and Rural
Appraisers
; Government Accountability Office (GAO), Conservation Reserve Program:
Cost-Effectiveness Is Uncertain
, March 1993; H. Feng, J. Zhao, and C. Kling, “Carbon: The
Next Big Cash Crop,” Choices, 2ndquarter 2001; and H. Feng, C. Kling, and P. Glassman,
“Carbon Sequestration, Co-Benefits, and Conservation Programs,” Choices, Fall 2004.
31 W. Hohenstein, “USDA Activities to Address Greenhouse Gases and Carbon
Sequestration,” presentation to Senate Energy Committee staff, February 15, 2007.

CRS-12
Other longer term estimates from USDA report the potential for net increases
in carbon sequestration ranging from 10 to 160 MMTCE per year in the United
States, or roughly 2-14 times current levels.32 Comparable estimates reported by EPA
forecast a higher sequestration potential for the U.S. agriculture sector, ranging from
40 to 270 MMTCE per year.33 EPA also reports additional sequestration potential
from livestock manure management, biofuels substitution, and other farm
management practices. USDA reports that other studies have forecast an even greater
potential to sequester carbon in the United States, ranging from about 90 to 320
MMTCE annually. Various estimates will differ depending on the extent that
estimates may include sequestration activities for the forestry sector.
Under USDA’s forecast, an additional carbon uptake of 160 MMTCE per year
would more than offset the agriculture sectors’ annual GHG emissions, or offset 8%
of total national emissions from all sources. Currently, carbon uptake in agriculture
soils sequesters under 1% of total national GHG emissions annually (Table 1).34
Per-Unit Value Estimates. Compared to other mitigation options in other
sectors, USDA reports that U.S. agriculture can provide low-cost opportunities to
sequester additional carbon in soils and biomass. The estimated per-unit value (or
cost) of carbon removed or sequestered, expressed on a dollar per metric ton (mt) of
carbon basis, will vary depending on the type of practice. Actual per-unit values and
the cost-effectiveness of different practices may vary considerably from site to site.
USDA’s forecast of an additional sequestration potential of 10-160 MMTCE is
associated with an estimated annual value ranging from $10/mt to $125/mt of carbon
permanently sequestered.35 The low end of this range reflects the sequestration
potential associated with cropland management practices; higher-end values are
associated with land retirement and conversion, and a longer sequestration tenure.
USDA’s report also notes that if producers discontinue the land and cropland
management practices at the end of a typical contract period, the carbon sequestered
may only be worth a small share of its overall program costs, because most of the
carbon will be released when these practices are terminated, which may lower the
cost-effectiveness of such programs. EPA’s forecast of an additional sequestration
potential for the agriculture sector, ranging from 40 to 270 MMTCE per year, is
estimated across a range of about $20/mt-$110/mt of sequestered carbon per year.36
32 USDA, Economics of Sequestering Carbon in the U.S. Agricultural Sector, April 2004.
33 EPA, “Greenhouse Gas Mitigation Potential in U.S. Forestry and Agriculture,” Tables 4-
10 and 4-5, November 2005, at [http://www.epa.gov/sequestration/greenhouse_gas.html].
Annualized over 15-years. Converted from EPA-reported CO equivalent.
2
34 Currently, about 11% of total GHG emissions are sequestered annually through the U.S.
agriculture and forestry sectors, with the bulk sequestered through growth in forest stocks.
35 USDA, Economics of Sequestering Carbon in the U.S. Agricultural Sector, April 2004;
measured by the amount of carbon that could be measured over a 15-year time period across
a range of costs. The associated total cost to sequester carbon across this range is estimated
from $0.95 billion to $2 billion per year.
36 EPA, “Greenhouse Gas Mitigation Potential in U.S. Forestry and Agriculture,” Table 4-
10, November 2005, at [http://www.epa.gov/sequestration/greenhouse_gas.html]. Converted
(continued...)

CRS-13
The low end of this range is associated with sequestration in agricultural soils and
with soil management practices; high-end values are associated with afforestation,
or converting open land into a forest by planting trees or their seeds.
Enhancing Carbon Sinks. There is potential to increase the amount of
carbon captured and stored in U.S. agricultural lands by adopting certain
conservation and land management practices. In most cases, such practices may both
sequester carbon in farmland soils and reduce emissions from the source. Table 2
shows estimated representative carbon sequestration rates for agricultural practices.
Improved Soil and Land Management. The main carbon sinks in the
agriculture sector are cropland conversion and soil management, including improved
manure application.37 More than half of all carbon sequestered on U.S. agricultural
lands is through voluntary land retirement programs and programs that convert or
restore land (e.g., conversion to open land or grasslands, conversion to cropland,
restoration of grasslands or wetlands, etc.). Undisturbed open lands, grasslands and
wetlands can hold carbon in the soil both underground in the root structure and above
ground in plant biomass. The amount of carbon sequestered will vary by the type of
land management system. Land retirement and grassland conversion stores between
0.3 and 0.5 metric tons (mt) of carbon per acre annually.38 Compared with other types
of systems, this is about twice the amount of carbon stored through tree plantings and
wetlands conversion, and about four times that stored on croplands.39
Table 2. Representative Carbon Sequestration Rates
(mt C/acre per year)
Reduced tillage (e.g., no-till, reduced-till)
0.2 - 0.3
Change in grassland management
0.02 - 0.5
Cropland conversion (grassland)
0.3 - 0.5
Riparian buffers
0.1 - 0.3
Biofuel substitution
1.3 - 1.5
Source: EPA, “Greenhouse Gas Mitigation Potential in U.S. Forestry and Agriculture,” Table 2-1.
Converted from reported CO equivalent units.
2
Conservation tillage is another major source of sequestration on farmlands,
accounting for about 40% of the carbon sequestered by the U.S. agricultural sector.40
36 (...continued)
from a reported range of $5-$30 per CO equivalent.
2
37 USDA, U.S. Agriculture and Forestry Greenhouse Gas Inventory: 1990-2001, TB1907,
Figure 3-8, March 2004, at [http://www.usda.gov/oce/global_change/gg_inventory.htm].
38 EPA, “Greenhouse Gas Mitigation Potential in U.S. Forestry and Agriculture,” Table 2-1,
November 2005, at [http://www.epa.gov/sequestration/greenhouse_gas.html]. Converted
from reported CO equivalent units.
2
39 Bongen, A.,”Using Agricultural Land for Carbon Sequestration,” Purdue University, at
[http://www.agry.purdue.edu/soils/Csequest.PDF]. 1999 data for carbon storage in Indiana.
40 USDA, U.S. Agriculture and Forestry Greenhouse Gas Inventory: 1990-2001, TB1907,
(continued...)

CRS-14
Improved tillage practices improve biomass retention in soils and reduce soil
disturbance, thereby decreasing oxidation. The amount of carbon sequestered will
vary by the type of tillage system: reduced tillage stores between 0.2-0.3 mt of carbon
per acre annually.41 Among conservation tillage practices, no-till stores about 30%
more than the amount of carbon stored by reduced tillage but more than five times
that stored on intensive tilled croplands. (Conservation tillage practices are explained
above, in the section on “Potential for Additional Reductions”).
Improved Manure and Feed Management. Mitigation strategies at U.S.
livestock operations are not commonly associated with carbon uptake and are not
included in EPA’s carbon sink estimates. However, installing manure management
systems, such as an anaerobic digester, captures and/or destroys methane emissions
from livestock operations and may be regarded as avoided emissions or as a form of
direct sequestration capturing emissions at the source. As a result, some carbon offset
programs are beginning to promote manure management systems as a means to
capture and store methane at dairy operations, which may also be sold as carbon
offset credits and as a renewable energy source.42 Given that there are currently few
anaerobic digesters in operation, estimates of the actual or potential uptake may be
difficult to estimate. (Manure management systems are further explained above, in
the section on “Potential for Additional Reductions”).
Mitigation Strategies in the Agriculture Sector
At the federal and state levels, existing conservation programs encourage the
types of agricultural practices that can reduce GHG emissions and/or sequester
carbon. Few federal programs specifically address climate change concerns in the
agriculture sector; however, several states have begun to adopt programs and
requirements intended to address such concerns.
Conservation Programs
Agricultural conservation practices broadly include land management,
vegetation, and structures that can reduce GHG emissions and/or sequester carbon
in the agriculture sector, such as:
! land retirement, conversion, and restoration programs (e.g.,
conversion to grasslands, restoration of grasslands or wetlands, etc.);
! soil conservation practices, including conservation tillage (e.g.,
reduced/medium- till, no/strip-till, ridge-till);
! soil management and soil erosion controls;
! precision agriculture practices and recognized agricultural best
management practices;
40 (...continued)
March 2004, at [http://www.usda.gov/oce/global_change/gg_inventory.htm]; USDA,
“Depositing Carbon in the Bank: The Soil Bank, That Is,” Agricultural Research, Feb. 2001.
41 EPA, “Greenhouse Gas Mitigation Potential in U.S. Forestry and Agriculture,” Table 2-1,
November 2005, at [http://www.epa.gov/sequestration/greenhouse_gas.html]. Converted
from reported CO equivalent units.
2
42 See Iowa Farm Bureau’s carbon credit project at [http://www.iowafarmbureau.com].

CRS-15
! efficient fertilizer/nutrient (including manure) and chemical
application;
! crop rotations;
! cover cropping;
! manure management (e.g., improve manure storage and technologies
using anaerobic digestion and methane recovery);
! feed management (e.g., improve feed efficiency, dietary
supplements);
! rotational grazing and improved forage/grazing management;
! vegetative and riparian buffers, and setbacks;
! windbreaks for crops and livestock;
! bioenergy and biofuels substitution and renewable energy use (e.g.,
replacing use of fossil fuels); and
! energy efficiency and energy conservation on-farm.
Conservation programs administered by USDA and state agencies encourage
farmers to implement certain farming practices and often provide financial incentives
and technical assistance to support adoption. Participation in these programs is
voluntary, and farmers may choose to discontinue participating in these programs.
Also, as previously noted, the effectiveness of these practices depends on the type of
practice, how well the practice is implemented, and also on the length of time a
practice is undertaken.
The fact that the types of conservation and land management practices being
promoted under existing agricultural conservation programs may also lower GHG
emissions and increase carbon uptake in agricultural soils should be regarded as an
incidental benefit of these programs. With few exceptions, these types of
conservation and land management programs were not initiated for the purpose of
reducing GHG emission or sequestering carbon, and the eligibility requirements
under these programs do not explicitly require emissions reductions or carbon
sequestration as objectives or selection criteria for participation. These programs are
generally designed to address site-specific improvements based on a conservation
plan developed with the assistance of USDA or state extension technical and field
staff that considers the goals and land resource base for an individual farmer or
landowner. Such a conservation plan is typically a necessary precursor to
participating in USDA’s conservation programs.
Federal Programs. USDA’s conservation and land management programs
are geared to taking land out of production and to improving land management
practices on land in production, commonly referred to as “working lands.” Most of
these programs are in Title II (Conservation) of the 2002 farm bill43 (Table 3).
! Land retirement/easement programs. Programs focused on land
management, including programs that retire farmland from crop
production and convert it back into forests, grasslands, or wetlands,
including rental payments and cost-sharing to establish longer term
conservation coverage. Major programs include the Conservation
Reserve Program (CRP), the Wetlands Reserve Program (WRP), the
43 For a list of the USDA programs, see USDA, “Farm Bill, Title II: Conservation,” at
[http://www.ers.usda.gov/Features/Farmbill/titles/titleII conservation.htm].

CRS-16
Grasslands Reserve Program (GRP), the Farmland Protection
Program (FPP), among other programs.
! Working lands programs. Programs focused on improved land
management and farm production practices, such as changing
cropping systems or tillage management practices, are supported by
cost-sharing and incentive payments, as well as technical assistance.
Major programs include the Environmental Quality Incentives
Program (EQIP), the Conservation Security Program (CSP), the
Agricultural Management Assistance (AMA) program, and the
Wildlife Habitat Incentives Program (WHIP).
In addition, there are forestry programs administered by USDA’s Forest Service.
Typically, however, there is often little overlap between the various agriculture and
forestry programs administered by USDA, and few forestry programs provide support
to agricultural enterprises. One exception is the Forest Service’s Forest Land
Enhancement Program (FLEP), which has an agroforestry component that provides
funding for agriculture and silvopasture practices with rotational grazing and
improved forage. Funding for agroforestry activities under this program constitutes
a small share of total FLEP funding.44 USDA’s agriculture conservation programs
also include its Healthy Forests Reserve Program, which has an agroforestry
component, but program funding is usually limited to a few states.
Renewable energy projects receive additional program funding across three farm
bill titles: Title II (Conservation), Title IX (Energy), and Title VI (Rural
Development). Other funding is also available through other federal programs.45 In
addition to cost-sharing programs provided under Title II programs, two other
important renewable energy programs under the 2002 farm bill are under Title IX
(Section 9006) and Title VI (Section 6013). Section 9006 authorized loans, loan
guarantees, and grants to farmers, ranchers, and rural small businesses to purchase
renewable energy systems and make energy efficiency improvements. Section 6013
authorized the business and industry program to make loans and loan guarantees for
renewable energy systems, including wind energy systems and anaerobic digesters.
Section 9006 and Section 6013 under the 2002 farm bill, as well as other cost-share
programs, account for the majority of federal program spending to support
construction of anaerobic digesters in the livestock sector.46 Limited information
indicates that USDA funded eight projects totaling more than $60 million under
Section 601347 and provided another $20 million in funding assistance under Section
600948 for anaerobic digesters (FY2002-FY2005).
44 Primary efforts under FLEP are afforestation and reforestation, improved forest stand,
constructing windbreaks, and riparian forest buffers.
45 See CRS Report RL32712, Agriculture-Based Renewable Energy Production, by Randy
Schnepf; and CRS Report RL33572, Biofuels Incentives: A Summary of Federal Programs,
by Brent Yacobucci.
46 CRS communication with USDA staff, February 8, 2007.
47 USDA, “Farm Bill Forum: Rural Development Title,” March 2006, at [http://www.usda.
gov/documents/RURAL_DEVELOPMENT_TITLE.pdf].
48 USDA, “USDA Funding Assistance for Rural Renewable Energy and Energy Efficiency:
(continued...)

CRS-17
Table 3. Conservation and Land Management Practices
USDA
Conservation Practice and
Benefits for Climate
Program
Land Management
General Benefits
Change
Conservation tillage and reduced field
Improves soil/water/air quality.
Sequestration,
pass intensity
Reduces soil erosion/fuel use.
emission reduction
EQIP,
Crop diversity through crop rotations
Reduces erosion/water needs.
Sequestration
CSP,
and cover cropping
Improves soil/water quality.
AMA
Efficient nutrient (nitrogen)
Improves water quality. Saves
Sequestration,
management, fertilizer application
expenses, time, and labor.
emission reduction
Improved soil management and soil
Improves soil/water/air quality.
Sequestration,
erosion controls
emission reduction
EQIP
Manure management (e.g.,
Improves soil/water/air quality.
Emission reduction
CSP
storage/containment, anaerobic
On-farm fuel cost-savings.
AMA
digestion and methane recovery)
Alternative income source.
Othera
Nutrients for crops.
Feed management (e.g., raise feed
Improves water/air quality. More
Emission reduction
EQIP
efficiency, dietary supplements)
efficient use of feed.
CSP
AMA
Rangeland management (e.g.,
Reduces water requirements.
Sequestration,
rotational grazing, improved forage)
Helps withstand drought. Raises
emission reduction
grassland productivity.
EQIP
Windbreaks for crops and livestock,
Improves crop/livestock protection
Sequestration,
CSP
vegetative/riparian buffers, grassed
and wildlife habitat. Alternative
emission reduction
AMA
waterways, setbacks, etc.
income source (e.g., hunting fees).
WHIP
FLEP
Agroforestry / silvopasture with
Provides income from grazing and
Sequestration,
EQIP
rotational grazing and improved
wood products.
emission reduction
CSP
forage
AMA
CRP
Land management, including
Improves soil/water/air quality.
Sequestration
WRP
retirement, conversion, restoration
GRP
(cropland, grasslands, wetlands, open
FPP
space)
EQIP
Energy efficiency/conservation
Improves soil/water/air quality.
Emission reduction
CSP
Cost-savings.
AMA
Othera
Biofuel substitution and renewable
Improves soil/water/air quality.
Emission reduction
energy use
On-farm fuel cost-savings.
Alternative income source.
Source: Compiled by CRS staff from USDA and EPA information. Listed programs: Conservation Reserve Program
(CRP), Wetlands Reserve Program (WRP), Grasslands Reserve Program (GRP), Farmland Protection Program (FPP),
Environmental Quality Incentives Program (EQIP), Conservation Security Program (CSP), Agricultural Management
Assistance (AMA), Wildlife Habitat Incentives Program (WHIP), and Forest Land Enhancement Program (FLEP).
a. Renewable energy projects receive additional program funding in farm bill under Title IX (Energy) and Title VI
(Rural Development), as well as other federal and state program.
48 (...continued)
Section 9006 of the 2002 Farm Bill,” at [http://power.wisconsin.gov/pdf/USDA
Presentation.pdf].

CRS-18
Funding for USDA’s conservation and land management programs totaled $5.6
billion in FY2005. Voluntary land retirement programs and programs that convert or
restore land account for roughly 37% annually of all USDA conservation spending
(Figure 3). Programs that provide cost-sharing and technical assistance to farmers
to implement certain practices, such as EQIP, CSP, and AMA, provide another 21%
annually.49 USDA’s conservation technical assistance and extension services account
for about one-fourth of all funding. Other federal funding through other programs
also generally promotes natural resource protection on U.S. farms. Generally, the
decision on how and where this funding is ultimately used is made at the individual
state level.
State Programs. State-level agriculture conservation and land management
programs are available to farmers in most states, and operate in much the same
manner as federal conservation programs. These programs may also provide financial
and technical assistance to farmers to implement certain practices, using additional
state resources and in consultation with state agricultural agencies and extension
staff. No single current compendium exists outlining the different types of
agricultural conservation programs across all states; instead information is available
through individual state government websites.50
Figure 3. USDA Conservation Spending, FY2005
Technical
Data & Research
Assistance,
11%
Extension,
Administration
26%
Rent &
Easements
37%
Cost Share
Public Works &
21%
Emergency
Payments 5%
Source: USDA, Office of Budget and Planning.
Note: FY2005 total spending = $5.6 billion.
Many states have cost-share programs that provide financial assistance to
landowners to implement practices that benefit a state’s forests, fish, and wildlife.
Many of these programs may provide technical assistance and up to 75% of the
49 EQIP and CSP were originally set to expire in FY2007 with most farm bill programs, but
were extended in the most recent budget reconciliation (P.L. 109-171). EQIP, the largest
program, is authorized through FY2010 and will reach $1.3 billion annually.
50 State and Local Government Internet directory at [http://www.statelocalgov.net/
index.cfm]).

CRS-19
eligible costs of approved conservation projects to qualified landowners. Several
states also provide low-interest financing to farmers and landowners to encourage
conservation practices or to implement best management practices for the agriculture
sector. Many states also have buffer strip programs, which may provide rental
payments to landowners who agree to create or maintain vegetative buffer strips on
croplands near rivers, streams, ponds, and wetlands. Typically states that have taxing
authority for conservation purposes within a state, such as Nebraska, Missouri, and
Oregon, will tend to have more stable funding and staffing to support conservation
improvements.
Climate Change Programs
Federal Programs. Currently, few USDA programs or conservation practices
are specifically intended to address climate change concerns in the agriculture sector.
One exception is USDA’s Conservation Innovation Grants program, a subprogram
under EQIP, which is intended to accelerate technology transfer and adoption of
innovative conservation technologies, mostly through pilot projects and field trials.
Past grants have supported development of approaches to reduce ammonia emissions
from poultry litter, promote conservation tillage, promote solar energy technologies,
and develop private carbon sequestration trading credits.51
USDA is evaluating how to better incorporate climate concerns into its
conservation programs.52 One option might include modifying its evaluation criteria
for ranking applications to its conservation programs by giving additional
consideration to projects that propose to reduce GHG emissions or sequester carbon.
Other options might include supporting market-based approaches, such as the
development of environmental services markets and trading, that might supplement
existing conservation and forestry programs.53 USDA also participates in several
ongoing federal interagency initiatives intended to address climate change concerns.
For example, USDA participates in a multi-agency research and development
program for climate change technology, as part of the U.S. National Climate Change
Technology Initiative.54 USDA also participates in the multi-agency Climate Change
51 USDA, “Reducing Agricultural Greenhouse Gas Emissions Through Voluntary Action,”
Statement by Bruce Knight of USDA’s Natural Resources Conservation Service at the
United Nations Framework Convention on Climate Change, December 2004, at
[http://www.nrcs.usda.gov/news/speeches04/climatechange.html]
52 W. Hohenstein, “USDA Activities to Address Greenhouse Gases and Carbon
Sequestration,” presentation to Senate Energy Committee staff, February 15, 2007.
53 USDA, USDA’s 2007 Farm Bill Proposals, Conservation Title, January 31, 2007, at
[http://www.usda.gov/documents/07title2.pdf]; statement by Mark Rey, USDA Under
Secretary for Natural Resources and Environment, at USDA’s 2007 Outlook Forum, March
2, Arlington, VA; statement by USDA staff at the 4th USDA Greenhouse Gas Conference,
February 6, Baltimore MD.
54 Established in 2001, the program conducts multi-agency review of the federal R&D
portfolio. The program is under the direction of the U.S. Department of Energy, in
coordination with the U.S. Department of Commerce [http://www.climatetechnology.gov/].
See CRS Report RL33817, Climate Change: Federal Expenditures, by Jane Leggett.

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Science Program, integrating federal research on climate and global change across
13 federal agencies, including USDA.55
State Programs. The Pew Center on Global Climate Change reports that
many ongoing state programs and demonstration projects are intended to promote
carbon storage and emissions reduction in the U.S. agriculture sector.56 For example,
several states, including Oregon, Wisconsin, Vermont, and North Carolina, are
promoting methane recovery and biofuels generation from livestock waste. A
program in Iowa is providing support and funding to promote switchgrass as a
biomass energy crop. In Maryland, income tax credits are provided for the production
and sale of electricity from certain biomass combustion. Georgia has a program that
leases no-till equipment to farmers. In addition, several states, including Nebraska,
Oklahoma, Wyoming, North Dakota, and Illinois, have formed advisory committees
to investigate the potential for state carbon sequestration. In California, an accounting
program is being developed to track possible future costs to mitigate GHG emissions
in the U.S. agriculture sector. An even greater number of state programs and
initiatives are geared toward climate change mitigation strategies in sectors other than
in the agriculture sector.57
Also in California, numerous efforts connected to the state’s climate change
initiatives involve the agriculture sector. For example, California has a manure
digester cost-share program to expand the use of dairy digesters as part of its broader
climate change initiative. Other agriculture projects include carbon sequestration
projects involving rice straw utilization, energy and water conservation, biofuels
support, soil management, and other types of renewable energy and manure
management programs for dairies.58 Many of California’s programs provide support
to comply with the state’s recently enacted emission reductions legislation.59
Other Programs and Incentives. Carbon offset or carbon credit trading
programs involving U.S. farmers and landowners have also been initiated and are
currently operating on a pilot basis in several states. Such market-based approaches
are intended to reward early adopters and help offset farm costs to install emissions
controls and/or practices that sequester carbon by providing a means for them to earn
55 Established in February 2002, the program is a collaborative interagency program,
designed to improve the government-wide management of climate science and climate-
related technology development; see [http://www.climatescience.gov/]. See CRS Report
RL33817, Climate Change: Federal Expenditures, by Jane Leggett.
56 Pew Center on Global Climate Change, State Activities, [http://www.pewclimate.org/doc
Uploads/state_activities.pdf]; and Learning from State Action on Climate Change,
[http://www.pew climate.org/docUploads/PewStatesBrief Feb2006%2Epdf].
57 See CRS Report RL33812, Climate Change: Actions by States to Address Greenhouse
Gas Emissions
, by Jonathan Ramseur.
58 California Climate Change Portal, “State of California Agencies’ Roles in Climate Change
Activities,” at [http://climatechange.ca.gov/policies/state_roles.html#dfg].
59 California’s Global Warming Solutions Act of 2006 (AB 32), which was enacted in
September 2006, codified the state’s goal of requiring California’s GHG emissions be
reduced to 1990 levels by 2020.

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and sell carbon credits.60 One program operated by the Iowa Farm Bureau involves
more than 1,400 producers in 12 states (mostly Iowa, Kansas, and Nebraska, but also
Illinois, Ohio, Michigan, Wisconsin, Minnesota, South Dakota, Missouri, Indiana,
and Kentucky),61 whose carbon credits may be sold on the Chicago Climate
Exchange.62 Similar types of programs have also been initiated in North Dakota
(operated by the North Dakota Farmers Union), Illinois (Illinois Conservation and
Climate Initiative), Indiana (Environmental Credit Corporation), and the Northwest
(Upper Columbia Resource Conservation and Development Council).63 These
programs generally cover some or all aspects of the following types of carbon capture
and storage activities: sustainable agriculture practices (including conservation tillage
and grass seedlings); planting of unharvested grasslands or tree-plantings; methane
capture and biogas production with manure digesters; wind, solar, or other renewable
energy use; controlled grasslands or pasture management; and also forest restoration.
Considerations for Congress
In the 109th Congress, more than 100 bills, resolutions, and amendments were
introduced addressing climate change.64 Legislative initiatives involving the
agriculture sector have been geared to increasing carbon sequestration on agricultural
lands, with most attention given to forestry activities and restoration, where the
potential to increase uptake and store carbon for long time periods is much greater.
Historically, climate-related legislative initiatives have not specifically focused on
emissions reductions in the agriculture sector. Instead, GHG emissions reductions
and carbon uptake are an incidental benefit of existing voluntary agricultural
conservation programs that provide financial and technical assistance to implement
certain farm management practices, predominately for other production or
environmental purposes.
The 2007 farm bill debate could expand the scope of ongoing climate change
initiatives to more broadly encompass the agriculture sector, promoting conservation
60 In the case of agriculture, refers to verifiable emissions credits that are earned by crop or
livestock operations for capturing and storing carbon either by reducing GHG emissions or
sequestering carbon. For trading purposes, one carbon credit is considered equivalent to one
metric ton of carbon dioxide emission reduced.
61 Iowa Farm Bureau, Carbon Credit Aggregation Pilot Project, at [http://www.
iowafarmbureau.com/special/carbon/]; CRS staff communication with Iowa Farm Bureau
staff, January 2007.
62 The Exchange is a voluntary, self-regulated, rules-based exchange. Its emission offset
program constitutes a small part of its overall program, which includes methane destruction,
carbon sequestration, and renewable energy. See [http://www.chicagoclimatex.com/].
63 For more information, see North Dakota Farmers Union at [http://www.ndfu.org], Illinois
Conservation and Climate Initiative at [http://www.illinoisclimate.org], and Environmental
Credit Corporation at [http://www.envcc.com].
64 CRS Report RL32955, Climate Change Legislation in the 109th Congress; Pew Center
on Global Climate Change, Legislation in the 109th Congress related to Global Climate
Change
, [http://www.pewclimate.org/what_s_being_done/in_the_congress/109th.cfm].

CRS-22
and land management practices that could further address climate change issues in
the sector. Other types of policy options to further encourage crop and livestock
producers to adopt the types of conservation practices that may also reduce GHG
emissions and sequester carbon include:
! expanding existing cost-sharing and technical assistance programs,
such as EQIP, CSP, and AMA, and other financial programs under
current farm legislation;
! expanding existing land retirement, conversion and restoration
programs, such as CRP, WRP, and GRP;
! modifying existing cost-sharing and land retirement programs to
give additional consideration to projects that propose to reduce GHG
emissions or sequester carbon;
! expanding existing research programs and demonstration projects,
such as funding under USDA’s Conservation Innovation Grants
program; and
! expanding access to low-cost loans, loan guarantees, grants,
incentive payments, and income tax credits to farmers, ranchers, and
rural small businesses, such as Section 9006 and Section 6013 under
the current farm bill legislation.
Following is a list of the types of questions that might be raised in the 110th
Congress in legislation and debate about global climate change in general, as well as
during the anticipated 2007 farm bill debate over existing federal conservation and
land management programs for the U.S. agriculture and forestry sectors.
! 2007 Farm Bill Debate. Where are the opportunities to expand
existing federal conservation and land management programs to
achieve greater emissions reduction and carbon sequestration in the
agriculture sector in the 2007 farm bill? How might emissions
reduction and carbon sequestration be integrated with the many other
goals of conservation programs? Should existing programs and
policies intended to promote agricultural conservation practices be
modified or augmented to better address climate change concerns?
How explicitly should climate change goals be addressed in the 2007
farm bill? How might emissions reductions and carbon sequestration
be promoted among the other broader environmental benefits of
conservation activities in the agricultural sector, such as improved
soil quality and productivity, improved water and air quality, and
wildlife habitat? Which programs or practices are the most
beneficial and cost-effective? Are there ways to rank applications
from farmers under existing programs to grant a higher weight to
proposals to address climate change goals? Are there existing state
programs that effectively address climate change and could be
adopted at the federal level?
! Emissions reductions. Should carbon sequestration efforts be
balanced by incentives to obtain additional emissions reductions in
the agricultural sector through improved conservation and farm
management practices, which could have a more immediate, direct,

CRS-23
and lasting effect on overall GHG emissions? How might the
existing regulatory framework for controlling air pollutants affect the
climate change debate? What are the potential options for reducing
GHG emissions at U.S. farming operations? How might cost
concerns be addressed that limit broader adoption of manure
management systems and also feed management strategies at U.S.
livestock operations?
! Carbon sequestration. What are the upper limits of carbon capture
and storage initiatives in the agriculture sector? For example, are
such carbon sinks temporary or long-lasting, and what limits exist on
their storage value? Do they rely appropriately on the willingness of
landowners to adopt or continue to implement a particular
conservation practice? Do they rely too heavily on the willingness
of landowners to convert existing farmland to open space or prevent
the conversion of existing farmland to non-farm uses? Are they cost-
effective when compared to sinks in other sectors? How might
concerns regarding uncertainty be addressed when measuring and
estimating the amount of carbon sequestered in agricultural soils?
! Carbon offset or credit trading programs. Is there a federal role
in possibly expanding existing federal conservation programs in
conjunction with efforts to create new market opportunities for
farmers by developing a carbon credit trading system? What are the
potential policy implications of establishing a carbon credit trading
system? What are the potential measurement, monitoring,
enforcement, and administrative issues of implementing such a
program? For example, how could stored carbon be measured and
verified; how much compensation is available and for how long;
what are required management practices; which accounting
methodologies should be used? Would such a system operate under
a voluntary or a mandatory framework?
! Bioenergy promotion. How might ongoing or anticipated initiatives
to promote U.S. bioenergy production, such as corn-based or
cellulosic ethanol, affect the options for land management or
conservation strategies that could increase carbon uptake on
agricultural lands and in agricultural soils? Might broader climate
change goals be affected by increased agricultural production in
response to corn-based ethanol? For example, might previously
retired land be brought back into corn production or might this result
in more intensive corn production, including fewer crop rotations
and planting area setbacks, which could raise emissions and reduce
the amount of carbon sequestered? Are there other competing
commercial crops that might be used as a feedstock for ethanol that
could also affect emissions and carbon uptake potential?
! Energy efficiency. What are the opportunities for improved on-farm
energy efficiency and conservation? How might these be integrated

CRS-24
into the broader framework on climate change mitigation in the
agricultural sector?
! Safeguarding U.S. agricultural production. Among the possible
effects of global climate change on agricultural production are
increased climate variability and increased incidence of global
environmental hazards, such as drought and/or flooding, pests,
weeds, and diseases, or location shifts in where agriculture is
produced. Climate change in some locations increases the yields of
some crops. Some U.S. production regions are likely to fare better
than others. Are additional initiatives needed in the U.S. agriculture
sector to prepare for the potentially effects of global climate change
that might impact U.S. agricultural production and food security?
Which regions and crops might be “winners” or “losers” and how
can transitions be eased?

CRS-25
Appendix: Primer on the Role of the U.S. Agriculture Sector
in the Climate Change Debate
Question
Discussion
What are the
Official estimates of greenhouse gas (GHG) emissions for the U.S. agriculture sector are
types of GHG
based on emissions of methane (CH ) and nitrous oxide (N O) associated with agricultural
4
2
emissions
production only. These estimates do not include carbon dioxide (CO ) emissions from on-
2
associated with
farm energy use and other emissions associated with forestry activities, food processing
U.S. agriculture?
or distribution, or biofuel production.
See Agricultural GHG Emissions in this report for more information.
What are the
Agricultural sources of CH emissions are mostly associated with the natural digestive
4
sources of GHG
process of animals and with manure management on U.S. livestock operations. Sources
emissions from
of N O emissions are mostly associated with soil management and fertilizer use on U.S.
2
agriculture?
croplands.
Figure 1 shows agricultural emissions by type and production category.
Why are CO
CO emissions from on-farm energy use are aggregated with emissions for all
2
2
energy emissions
transportation and industrial sectors, and comprise a small share of this total. Even if
excluded?
included in the estimates for the agriculture sector, this would not substantially raise
agriculture’s overall share of total GHG emissions.
What is
In 2004, GHG emissions from U.S. agricultural activities totaled 120 MMTCE (million
agriculture’s
metric tons of carbon equivalent units), accounting for 6% of the annual national GHG
share of annual
emissions (Table 1). Fossil fuel combustion is the leading source of national GHG
national GHG
emissions (80%), with the energy sector generating about 86% of annual emissions across
emissions?
all U.S. sectors.
How much
In 2004, agricultural soils sequestered about 12.4 MMTCE of carbon, or one-tenth of the
carbon is
carbon-equivalent of reported annual emissions generated from agriculture. Compared to
sequestered in
total national GHG emissions, the agriculture sector offsets less than 1% of emissions
U.S. agricultural
annually. These estimates do not include uptake from forested lands or open areas that
soils?
account for a majority (94%) of total U.S. sequestration. Figure 2 shows carbon
sequestration in agricultural soils. Also see Agricultural Carbon Sinks for more
information.
Is there any
Reasons for uncertainty associated with uptake estimates in U.S. soils include: actual
uncertainty
uptake depends on site specific conditions (e.g., location, climate, soil type, crop type,
associated with
tillage practices, crop rotations, farm management, etc.); accounting methodology; type
estimates of
of practice, how well it is implemented, and the length of time undertaken; availability of
carbon uptake for
federal/state cost-sharing or technical assistance; and other competing factors (including
the agriculture
supply response for commercial crops and bioenergy crops). Actual GHG emissions may
sector?
also vary according to many site-specific conditions.
See Uncertainty Estimating Carbon Sinks for more information.
What is the
The potential for carbon uptake in U.S. agricultural soils is much greater than current rates,
potential to
with estimated net increases in carbon sequestration ranging from 10-160 MMTCE per
reduce emissions
year, or even higher. This could offset total national GHG emissions by as much as 2-15%
and/or increase
or higher, which is substantially greater than the current estimate that farmland soils offset
carbon uptake in
about 1% of annual national GHG emissions. Practices that may reduce emissions and/or
the agriculture
sequester carbon on U.S. farmlands include land retirement, conversion, and restoration;
sector?
improved soil management and conservation tillage on U.S. croplands; and improved
manure management and feeding strategies at U.S. livestock operations.
See sections Potential for Additional Uptake and Potential for Additional Reductions.

CRS-26
Question
Discussion
How costly are
The estimated value (or cost) of sequestered carbon will vary by practice. USDA’s forecast
the types of
of an additional sequestration potential of 10-160 MMTCE is associated with an estimated
farming practices
per-unit value ranging from $10-$125/mt of carbon per year. EPA’s reported potential of
that help address
40-270 MMTCE per year is forecast across a range of about $20-$110/mt of carbon
climate change
sequestered per year. The low-end of this range reflect the sequestration potential
issues?
associated with cropland management practices; higher-end values are associated with land
retirement and afforestation.
See Potential Mitigation Costs for more information.
How can
Most land management and agricultural conservation practices might both reduce GHG
emissions from
emissions and/or sequester carbon, including land retirement, conversion, and restoration;
production be
conservation tillage; soil management and soil erosion controls; efficient fertilizer/nutrient
reduced? How
and chemical application; crop rotations; cover cropping; manure management; feed
can carbon
management; rotational grazing and improved forage; vegetative and riparian buffers;
uptake in
windbreaks for crops and livestock; bioenergy substitution and renewable energy use; and
agricultural soils
energy efficiency and energy conservation on-farm. See Table 2 for more information.
be increased?
See Mitigation Strategies in the Agriculture Sector for more information.
Are there
Existing federal and state farm conservation programs promote the types of land
existing
management and conservation practices that can reduce GHG emissions and/or sequester
programs and/or
carbon. Also, many existing voluntary programs in the current farm bill, as well as under
legislation that
existing state-level programs provide cost-sharing and technical assistance to encourage
promote farming
farmers to implement such practices. These are voluntary programs and are generally
practices that
designed to address site-specific improvements at an individual farming operation.
may help address
See Federal Programs and other listed program information.
climate change?
Source: Table prepared by the Congressional Research Service.