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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 #357520

Research Project: Improved Practices to Conserve Air Quality, Maintain Animal Productivity, and Enhance Use of Manure and Soil Nutrients of Cattle Production Systems for the Southern Great Plains

Location: Livestock Nutrient Management Research

Title: Unscrambling nitrous oxide production in beef cattle feedyard manure: Effect of temperature and water content on denitrification rates

Author
item Waldrip, Heidi
item Parker, David
item Miller, Sierra - Former ARS Employee
item Casey, Kenneth - Texas A&M Agrilife
item Todd, Richard - Rick

Submitted to: International Livestock Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 11/29/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Nitrous oxide is a potent greenhouse gas that is emitted from accumulated manure in beef cattle feedyard pens. Recent research has greatly advanced our understanding of the magnitude of nitrous oxide emissions from feedyards; however, the primary mechanism by which nitrous oxide is produced (i.e., nitrification, denitrification, coupled nitrification-denitrification, etc.) is unclear. Effective mitigation of feedyard nitrogen losses via manure management, addition of inhibitors, or use of other chemical or organic compounds requires a detailed understanding of how nitrous oxide is formed under varying conditions. Temperature and water content are primary factors affecting nitrous oxide emissions from manure. The objective of this research was to determine how temperature affects potential denitrification enzyme activity (DEA) from feedyard manure following rainfall. A recirculating-flow-through, non-steady-state (RFT-NSS) chamber system was used to monitor emissions from manure following a single 25.4 mm rainfall event. Emissions were monitored at manure temperatures of 5.0, 11.2, 17.2, 21.5, 26.8, 31.0, 38.1, and 46.2 °C. Manure samples were collected at depths of 0-5 cm and 5-10 cm immediately after rainfall and at regular intervals during the study. These were analyzed for potential DEA using an Ankom Gas Production System, where manure was incubated under anaerobic conditions with high levels of nitrate and glucose. DEA rates were expressed as nitrate disappearance over time. These data were regressed against measured nitrous oxide emissions, manure physicochemical properties (e.g., pH, redox status, and ammonium/ammonia, nitrite/nitrate and soluble carbon concentrations) to evaluate how temperature and water content affect the potential denitrification rate in feedyards. This work is still in progress and detailed data are not currently available; however, information derived from this study will be useful for developing mitigation methods that reduce greenhouse gas emissions from commercial beef feedyards is the southern High Plains.