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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Publications at this Location » Publication #304219
Title: Chapter 5: Quantifying greenhouse gas sources and sinks in animal production systems

Author
item POWERS, WENDY - Michigan State University
item AUVERMANN, BRENT - Texas A&M Agrilife
item Cole, Noel
item GOOCH, CURT - Cornell University
item GRANT, RICH - Purdue University
item Hatfield, Jerry
item Hunt, Patrick
item JOHNSON, KRISTEN - Washington State University
item Leytem, April
item LIAO, WEI - Michigan State University
item Powell, Joseph

Submitted to: Government Publication/Report
Publication Type: Government Publication
Publication Acceptance Date: 5/15/2014
Publication Date: 7/31/2014
Citation: Powers, W., Auvermann, B., Cole, N.A., Gooch, C., Grant, R., Hatfield, J.L., Hunt, P.G., Johnson, K., Leytem, A.B., Liao, W., Powell, J.M. 2014. Chapter 5: Quantifying greenhouse gas sources and sinks in animal production systems. Government Publication/Report. Chapter 5: 31-160.

Interpretive Summary: There is growing concern about global climate change and the effects that greenhouse gases (GHG) may have on the climate. Agricultural production systems are potential sources of GHG; however, net GHG production from different phases of U.S., agriculture, and methods to mitigate these emissions are not well documented. The purpose of this publication is to develop methods to estimate GHG from U.S. agriculture and forestry and to also estimate the effects of differing management practices on emissions. This chapter provides guidance for reporting GHG emissions from animal production systems; in particular beef cattle, dairy cattle, sheep, swine, and poultry. The methods recommended are based on the best available data at the time. In some cases methods are oversimplified because of limited data. This chapter provides insight into the current state of the science and serves as a starting point for future assessments. The chapter is broken into five 5 subchapters: 5.1 summarizes animal management practices and the resulting GHG emissions, 5.2 presents an overview of each production system and a general discussion of common management systems and practices, 5.3 describes the recommended methods for estimating GHG emissions from enteric fermentation and housing, 5.4 describes recommended methods for estimating GHGs from manure management systems, and 5.5 identifies research gaps that exist for quantifying GHGs from animal production systems. The methods provided in this report range from the simple Tier 1 approach recommended by the International Panel on Climate Change (IPCC) to the most complex Tier 3 and mechanistic model approaches. The more complex methods are expected to reduce uncertainties in the emission estimates.

Technical Abstract: The purpose of this publication is to develop methods to quantify greenhouse gas emissions (GHG) from U.S. agriculture and forestry. This chapter provides guidance for reporting GHG emissions from animal production systems. In particular, it focuses on methods for estimating emissions from beef cattle (cow-calf, stocker, and feedlot systems), dairy cattle, sheep, swine, and poultry (layers, broilers, and turkey). Information provided is based on available data at the time of writing. In many cases systems are oversimplified because of limited data availability. It is expected that more data will become available over time. This chapter provides insight into the current state of the science and serves as a starting point for future assessments. Section 5.1 summarizes animal management practices and the resulting GHG emissions. Section 5.2 presents an overview of each production system and a general discussion of common management systems and practices. Section 5.3 describes the methods for estimating GHG emissions from enteric fermentation and housing (enteric fermentation being a much more significant emissions source than housing). Section 5.4 describes methods for estimating GHGs from manure management systems. Section 5.5 identifies research gaps that exist for quantifying GHGs from animal production systems. The intent of identifying research gaps is to highlight where improvements in knowledge can best improve the usefulness of this document at farm-, regional-, and industry-scales. For this report, methods are categorized according to those from enteric fermentation, housing, and manure management systems. The housing discussion includes emissions from manure deposited in the housing unit and manure that is managed inside those areas (such as interior stockpiles). Manure management includes emissions from managed, treated, and stored manure. System boundaries are defined by the coverage, extent, and resolution of the estimation methods. The methods in this report can be used to estimate GHG emission sources that occur within the production area of an animal production system, including the animals, animal housing, and manure handling, treatment, and storage. For emissions from animal production systems, the methods provided have a resolution of individual herds within an entity’s operation. Emissions are estimated for each individual herd within an operation and then added together to estimate the total animal production emissions for an entity. The animal production totals are then combined with emissions from croplands, grazing lands, and forestry to determine the overall emissions from the operation based on the methods provided in this document. Emissions are estimated on an annual basis. The methods provided in this report range from simple IPCC Tier 1 approaches to the most complex Tier 3 approaches. Higher-tier methods are expected to reduce uncertainties in the emission estimates, if sufficient activity data and testing are available.