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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Soil Management and Sugarbeet Research » Research » Publications at this Location » Publication #323398
Title: Chapter 3: Cropland Agriculture

Author
item Del Grosso, Stephen - Steve
item OGLE, STEPHEN - Colorado State University
item Reyes-Fox, Melissa
item Nichols, Kristopher
item MARX, ERNIE - Colorado State University
item SWAN, AMY - Colorado State University

Submitted to: Government Publication/Report
Publication Type: Government Publication
Publication Acceptance Date: 5/2/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: In 2013, cropland agriculture resulted in total emissions of approximately 209 MMT CO2 eq. of greenhouse gases (GHG). Cropland agriculture is responsible for almost half (46%) of all emissions from the agricultural sector. Nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) emissions from cropped soils totaled 168, 33, and 9 MMT CO2 eq., respectively, in 2013. However, that amount was offset by a storage, or carbon sequestration, of 34 MMT CO2 eq. in cropped mineral soils in 2013. Greenhouse gas emission from agricultural soils, primarily N2O, were responsible for the majority of total emissions (80%), while CH4 and N2O from residue burning and rice cultivation caused about 4% of emissions in 2013. Soil CO2 emissions from cultivation of organic soils (13%) and from liming (3%) are the remaining sources. Nitrous oxide emissions from soils are the largest source in the U.S. because N2O is a potent greenhouse gas and due to the large amounts of nitrogen added to crops from fertilizer amendments and legume cropping that stimulates N2O production.

Technical Abstract: In 2013, cropland agriculture resulted in total emissions of approximately 209 MMT CO2 eq. of greenhouse gases (GHG). Cropland agriculture is responsible for almost half (46%) of all emissions from the agricultural sector. Nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) emissions from cropped soils totaled 168, 33, and 9 MMT CO2 eq., respectively, in 2013. However, that amount was offset by a storage, or carbon sequestration, of 34 MMT CO2 eq. in cropped mineral soils in 2013. The 95% confidence interval for net emissions in 2013 is estimated to lie between 129 and 249 MMT CO2 eq. In 2013, net emissions from cropland agriculture were about 50% higher than the baseline year (1990) mainly because N2O emissions have increased and the CO2 sink in mineral soils has diminished. Greenhouse gas emission from agricultural soils, primarily N2O, were responsible for the majority of total emissions (80%), while CH4 and N2O from residue burning and rice cultivation caused about 4% of emissions in 2013. Soil CO2 emissions from cultivation of organic soils (13%) and from liming (3%) are the remaining sources. Nitrous oxide emissions from soils are the largest source in the U.S. because N2O is a potent greenhouse gas and due to the large amounts of nitrogen added to crops from fertilizer amendments and legume cropping that stimulates N2O production. Emissions from residue burning are minor because only ~3% of crop residue is assumed to be burned in the U.S. Cropped mineral soils in the U.S. are a net CO2 sink mainly because reduced tillage intensity has become more popular in recent years and lands used for perennial hay cropping, as well as idle cropland enrolled in the Conservation Reserve Program (CRP), continue to store carbon. However, the magnitude of this sequestration in recent years is not as great as it was during the 1990’s, partially due to land conversion from CRP back to cropping and lands that have been in CRP for 15 years or more storing less carbon than they did initially.