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Climate Change

Sources of Greenhouse Gas Emissions

Agriculture Sector Emissions

photo of cows in a field
Total U.S. Greenhouse Gas Emissions by Economic Sector in 2014
Pie chart of total U.S. greenhouse gas emissions by economic sector in 2014. 30 percent is from electricity, 26 percent is from transportation, 21 percent is from industry, 12 percent is from commercial and residential, and 9 percent is from agriculture.

Total Emissions in 2014 = 6,870 Million Metric Tons of CO2 equivalent
*Land Use, Land-Use Change, and Forestry in the United States is a net sink and offsets approximately 11% of these greenhouse gas emissions.
All emission estimates from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2014.

Agricultural activities - the cultivation of crops and livestock for food - contribute to emissions in a variety of ways:

  • Various management practices for agricultural soils can lead to production and emission of nitrous oxide (N2O). The large number of different activities that can contribute to N2O emissions from agricultural lands range from fertilizer application to methods of irrigation and tillage. Management of agricultural soils accounts for over half of the emissions from the Agriculture sector.*
  • Livestock, especially cattle, produce methane (CH4) as part of their digestion. This process is called enteric fermentation, and it represents almost one third of the emissions from the Agriculture sector.
  • The way in which manure from livestock is managed also contributes to CH4 and N2O emissions. Manure storage methods and the amount of exposure to oxygen and moisture can affect how these greenhouse gases are produced. Manure management accounts for about 14% of the total greenhouse gas emissions from the Agriculture sector in the United States.
  • Smaller sources of emissions include rice cultivation, which produces CH4, and burning crop residues, which produce CH4 and N2O.

More national-level information about emissions from agriculture can be found in the agriculture chapter in the Inventory of U.S. Greenhouse Gas Emissions and Sinks.

*Management of agricultural soils can also lead to emissions of carbon dioxide (CO2). However, these emissions are included under the Land Use, Land-Use Change, and Forestry sector.

In 2014, greenhouse gas emissions from agriculture accounted for approximately 9% of total U.S. greenhouse gas emissions. Greenhouse gas emissions from agriculture have increased by approximately 11% since 1990. One driver for this increase has been the 54% growth in combined CH4 and N2O emissions from livestock manure management systems, reflecting the increased use of emission-intensive liquid systems over this time period. Emissions from agricultural soil management have also increased by about 5% since 1990. Emissions from other agricultural sources have either remained flat or changed by a relatively small amount since 1990.

To learn about projected greenhouse gas emissions to 2020, visit the U.S. Climate Action Report 2014 (PDF) (310 pp., 23.1 MB).

Greenhouse Gas Emissions from Agriculture
Line graph of greenhouse gas emissions from agriculture for 1990 to 2014. There are three lines - one for total emissions, a second for direct emissions, and a third shows indirect emissions from electricity. The direct and total emissions lines rise unevenly from 1990 to 2014 with slight increases in 1998, 2004, and 2007 followed by a steady increase through 2014. The direct emissions start around 560 million metric tons of carbon dioxide equivalents in 1990, and rose to a peak of about 635 million around 2012. Total emissions are around 690 million in 2014. The indirect emissions remain relatively constant throughout the time series, around 65 million metric tons of carbon dioxide equivalents.

All emission estimates from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2014.

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Reducing Emissions from Agriculture

The table shown below provides some examples of opportunities to reduce emissions from agriculture. For a more comprehensive list of options and a detailed assessment of how each option affects different gases, see Chapter 8 of the Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Link to EPA's External Link Disclaimer

Examples of Reduction Opportunities for the Agriculture Sector
Type How Emissions are Reduced Examples
Land and Crop Management Adjusting the methods for managing land and growing crops.
  • Fertilizing crops with the precise amount of nitrogen required, since less efficient nitrogen application can lead to higher N2O emissions.
  • Draining water from wetland rice soils during the growing season to reduce CH4 emissions.
Livestock Management Adjusting feeding practices and other management methods to reduce the amount of CH4 resulting from enteric fermentation. Improving pasture quality to increase animal productivity, which can reduce the amount of CH4 emitted per unit of animal product. Also, increased productivity can be accomplished through breeding.
Manure Management
  • Controlling the way in which manure decomposes to reduce N2O and CH4 emissions.
  • Capturing CH4 from manure decomposition to produce renewable energy.
  • Handling manure as a solid or depositing it on pasture rather than storing it in a liquid-based system such as a lagoon. This would likely reduce CH4 emissions but may increase N2O emissions.
  • Storing manure in anaerobic containment areas to maximize CH4 production and then capturing the CH4 to use as an energy substitute for fossil fuels.
  • For more information see EPA's AgSTAR Program, a voluntary outreach and education program that promotes recovery and use of methane from animal manure.

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