Location: Livestock Nutrient Management ResearchTitle: Nitrous oxide from beef cattle feedyards: Understanding effects of microbial community structure, climate and manure properties Author
|Casey, Kenneth - Texas A&m Agrilife|
|Todd, Richard - Rick|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/21/2018
Publication Date: N/A
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 nitrous oxide 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) and nitrification enzyme activity (NA) from feedyard manure following rainfall. A recirculating-flow-through, non-steady-state (RFT-NSS) chamber system was used to monitor nitrous oxide 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 and NA. In addition, microbial community structure at different depths and over time was analyzed via 16s DNA sequencing. These data were regressed against measured emissions, manure physicochemical properties (e.g., pH, redox status, and ammonium/ammonia, nitrite/nitrate and carbon concentrations) to evaluate how temperature, water content, and the microbial population affect potential denitrification and nitrification rates in feedyards. Information derived from this study will be useful for developing targeted mitigation methods that reduce greenhouse gas emissions from commercial beef feedyards on the southern High Plains.