Dinitrogen and methane gas production during the anaerobic/anoxic decomposition of animal manure

• Published in: Nutrient cycling in agroecosystems 2014, Vol.100 (1), p.53-64
• Main Authors: Harper, Lowry A, Weaver, Kim H, De Visscher, Alex
• Format: Article
• Language: English
• Subjects: Agriculture; Agronomy. Soil science and plant productions; air quality; air temperature; ammonia; animal feeding operations; animal manures; Applied sciences; Biological and medical sciences; Biomedical and Life Sciences; carbon; denitrification; engineering; Exact sciences and technology; farms; Fundamental and applied biological sciences. Psychology; gas emissions; gases; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; global change; Life Sciences; methane; methane production; methanogens; nitrification; nitrogen; Original Article; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Pollution; Soil-plant relationships. Soil fertility. Fertilization. Amendments; statistical models; surface area; swine; Use of agricultural and forest wastes. Biomass use, bioconversion; Wastes
• ISSN: 1385-1314; 1573-0867
• DOI: 10.1007/s10705-014-9626-9

Trace-gas emissions from animal feeding operations (AFOs) can contribute to air quality and global change gases. Previous and current estimated gas emissions from AFOs vary widely and many do not consider all forms of carbon (C) and nitrogen (N) emissions. Studies have found that as methanogenesis in the lagoons increased, conversion of ammonium (NH₄ ⁺) to dinitrogen (N₂) also increased. The purpose of this research was to measure N₂ and CH₄ emissions from swine AFOs in three locations of the U.S. and to evaluate the possible universal relationship between lagoon methanogenesis and the conversion of NH₄ ⁺ to N₂ gas. This relationship was tested by measuring N₂ and CH₄ emissions in two climates at 22 different farms. Methanogenesis was correlated with NH₄ ⁺-to-N₂ conversion by a near-constant N₂ to CH₄ emissions ratio of 0.20, regardless of C loading and climatic effects. The process is shown to be thermodynamically favored when there is competition between NH₄ ⁺ oxidizing reactions. Under methanogenic conditions (redox potentials of methanogenesis) N₂ production is favorable and nitrification/denitrification is not. Thus, N₂ production is stimulated in methanogenic conditions. Evaluation of NH₃ gas emissions from AFOs must consider other N emissions than NH₃. Finally, a statistical model was developed to estimate methane and N₂ emissions (kg gas ha⁻¹) given feed input per lagoon surface area (kg feed ha⁻¹) and local air temperature. Further studies are needed to investigate the mechanisms involved in manure processing and isolate the favorable mechanisms into engineering improved manure processing.