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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 #323397
Title: Chapter 2: Livestock and Grazed Lands Emissions

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

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

Interpretive Summary: A total of 342 MMT CO2 eq. of greenhouse gasses (GHGs) were emitted from livestock, managed livestock waste, and grazed land in 2013. This represents about 66% of total emissions from the agricultural sector, which totaled 516 MMT CO2 eq. Compared to the Enteric fermentation contributed to a little less than half (165 MMT CO2 eq.) of all emissions associated with livestock production, while soils from grazed lands (102 MMT CO2 eq.) and managed waste (76 MMT CO2 eq.) accounted for approximately 30% and 22%, respectively, of the total emissions. All of the emissions from enteric fermentation and about 77% of emissions from managed livestock waste were in the form of methane (CH4). Of the emissions from grazed lands, 94% were in the form of nitrous oxide (N2O) from soils. The largest total emissions associated with livestock production were from Texas and California. Emissions were high in Texas primarily because of the large numbers of beef cattle, while dairy cattle emissions are responsible for most emissions in California. Emissions were also relatively high in Idaho, Montana, South Dakota, Nebraska, Colorado, Kansas, Oklahoma, Wisconsin, Iowa and Missouri.

Technical Abstract: A total of 342 MMT CO2 eq. of greenhouse gasses (GHGs) were emitted from livestock, managed livestock waste, and grazed land in 2013. This represents about 66% of total emissions from the agricultural sector, which totaled 516 MMT CO2 eq. Compared to the base line year (1990), emissions from livestock sources were about 18% higher in 2013. There are three main reasons for this increase: CH4 emissions from managed livestock waste increased, N2O emissions from grazed lands increased, and the CO2 sink strength of grazed lands decreased. The 95% confidence interval for 2013 was estimated to lie between 293 and 407 MMT CO2 eq. Enteric fermentation contributed to a little less than half (165 MMT CO2 eq.) of all emissions associated with livestock production, while soils from grazed lands (102 MMT CO2 eq.) and managed waste (76 MMT CO2 eq.) accounted for approximately 30% and 22%, respectively, of the total emissions. All of the emissions from enteric fermentation and about 77% of emissions from managed livestock waste were in the form of methane (CH4). Of the emissions from grazed lands, 94% were in the form of nitrous oxide (N2O) from soils. Soils in grazed lands do not often experience the anaerobic conditions required for CH4 production to exceed CH4 uptake. However, a small portion of manure from grazing animals is converted to CH4 during the short period of time when paddies are drying. Although lands converted to grazing are estimated to be a C sink, this is balanced by long term grazed lands being a C source and in aggregate soils in grazed lands are estimated to be roughly CO2 neutral, with an estimate of 3.3 MMT net emission of CO2 in 2013. The largest total emissions associated with livestock production were from Texas and California. Emissions were high in Texas primarily because of the large numbers of beef cattle, while dairy cattle emissions are responsible for most emissions in California. Emissions were also relatively high in Idaho, Montana, South Dakota, Nebraska, Colorado, Kansas, Oklahoma, Wisconsin, Iowa and Missouri.