Dynamics and Controls of Nitrous Oxide Emission in Bioenergy Croplands
N2O is the third important long-lived greenhouse gas and croplands are considered biogeochemical hotspots. Excessive use of N fertilizers is an important factor. The emissions and crop productivity are strongly influenced by extremes in precipitation. The dynamics of N2O are determined by processes of nitrification and denitrification, therefore soil microbial community plays a major role. In this study, we evaluated the impacts of biochar application, N fertilization, and precipitation change on soil N2O flux. We hypothesized application of biochar reduces the emission depending on certain properties, application of N fertilization alters the soil microbial composition and abundance, and background precipitation has impacts on the responses of crop yield and N2O emission. We evaluated meta-analyses on the effects of biochar application on soil N2O emissions and proposed a grand mean response ratio to estimate an overall effect and the impacts of different properties. We then simulated corn yield and N2O emission using the DNDC model based on a long-term precipitation dataset and manipulated precipitation treatments. To quantify the impact of nitrogen application on microbial community, DNA extraction with paired end sequencing was performed. The results showed that biochar application reduced soil N2O emission by 38.8% in general. Grain yield increased with an increased precipitation until an optimal amount and decreased with decreasing precipitation. While drought conditions resulted in a decrease in the emission of soil N2O, high intensity precipitation enhanced it. Different ecosystems respond differently to N fertilization and such changes in the ecosystem affect microbial composition and abundance.
Ecology|Biogeochemistry|Agricultural chemistry|Soil sciences
"Dynamics and Controls of Nitrous Oxide Emission in Bioenergy Croplands"
ETD Collection for Tennessee State University.