Lead Authors:
Alexander N. Hristov, The Pennsylvania State University
Jane M. E. Johnson, USDA Agricultural Research Service
Contributing Authors:
Charles W. Rice, Kansas State University
Molly E. Brown, University of Maryland
Richard T. Conant, Colorado State University
Stephen J. Del Grosso, USDA Agricultural Research Service
Noel P. Gurwick, U.S. Agency for International Development
C. Alan Rotz, USDA Agricultural Research Service
Upendra M. Sainju, USDA Agricultural Research Service
R. Howard Skinner, USDA Agricultural Research Service
Tristram O. West, DOE Office of Science
Benjamin R. K. Runkle, University of Arkansas
Henry Janzen, Agriculture and Agri-Food Canada
Sasha C. Reed, U.S. Geological Survey
Nancy Cavallaro, USDA National Institute of Food and Agriculture
Gyami Shrestha, U.S. Carbon Cycle Science Program and University Corporation for Atmospheric Research
Science Lead:
Sasha C. Reed, U.S. Geological Survey
Review Editor:
Rachel Melnick, USDA National Institute of Food and Agriculture
Federal Liaisons:
Nancy Cavallaro, USDA National Institute of Food and Agriculture
Carolyn Olson (former), USDA Office of the Chief Economist


A number of social and economic factors drive CO2 and other GHG emissions associated with agriculture (see Table 5.1), including dietary preferences and traditions; domestic and global commodity markets; federal incentives for conservation programs; and technical capabilities for production, processing, and storage in different geographic regions. For example, policies and economic factors that influence bioenergy and biofuel feedstock production systems have diverse direct and indirect impacts on the carbon cycle as discussed later in this chapter and in Ch. 3: Energy Systems. A biofuel’s carbon footprint depends on the feedstock and its associated management as well as the efficiency of the eventual energy produced from the feedstock. Changes in the management of these social and economic factors can affect soil carbon sequestration and storage and agricultural GHG emissions. Another driver of changes in agricultural production systems is consumer demand for types of food (e.g., meat versus dairy versus vegetable) and provenance of food (e.g., grass-fed, organic, and local). Such influences can have both negative and positive effects on the carbon cycle in direct and indirect ways (see Box. 5.1, Food Waste and Carbon). Decision support tools have been developed over the last decade to address agricultural impacts on climate and environmental drivers that play a role in the carbon cycle (for examples, see Ch.18: Carbon Cycle Science in Support of Decision Making).

Table 5.1. Greenhouse Gas Fluxes from North American Agriculture
(Teragrams of Carbon Dioxide Equivalent per Year)

Emission Source Canadaa United Statesb Mexicoc Total by Source
Enteric Fermentation 25 166.5 43.3 234.8
Manure Management 8 84.0 25.7f 117.7
Agricultural Soil Management 24d 295.0 0 318.0
Rice Cultivation 0 12.3 0.2 12.5
Liming, Urea Application, and Others 3 8.7 7.5g 19.2
Field Burning of Agricultural Residues 0 0.4 1.3 1.7
Crop Residues NRe NR 1.9 1.9
Total by Countryh 60 566.9 79.9 705.8

a Source: ECCC (2018); data for 2016.
b Source: U.S. EPA (2018); data for 2015.
c Source: FAOSTAT (2017); average data for 1990–2014.
d Includes emissions from field burning of agricultural residues.
e Not reported.
f Includes manure applied to soils, manure left on pasture, and manure management.
g Synthetic fertilizer.
h As reported in source; may not match sum of individual emission categories due to rounding.

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