Developing a management system of animal manure to reduce greenhouse gas emission and water contamination

点击翻译按钮获取中文摘要

The research was conducted at a reed canary grass field, where Andisol was predominant, applied with dairy cattle manure. Estimates of evapotranspiration in the field using an energy balance method were agreed well with those with the standard Bowen ratio method. The fluxes of greenhouse and other gases, N_2O, CO_2, CH_4, and NH_3, were continuously measured using the conditional sampling method. It was found that there were cyclic exchanges of N_2O and CO_2 gases between the atmosphere and the ground even in a snow accumulated season. By measuring the natural abundance of nitrogen isotopes, δ^<15>N, in ammonium-, NH_4^+-, and nitrate, NO_3^--, nitrogen, we found that just after the manure application the volatilization and nitrification of NH_3, immediately followed by denitrification, occurred. Thus, it was implied that the N_2O gas emission after the manure application was attributed to both the processes of nitrification and denitrification. As the rate of nitrification decreased w … More ith decreases in soil temperature, the N_2O gas flux observed during the snow accumulated season might be caused by denitification. We also found that the N_2O gas flux increased linearly with increases in soil water content. This might result in a large spike of N_2O gas flux occurred after rainfall events. As the adsorption of anions by the Andisol was evident, the anion adsorption might cause the relatively small amounts of anions transported to the groundwater. The year-round emission of N_2O gas from the grass field might be resulted from the denitrification of the NO_3^- ion adsorbed by Andisol. We evaluated that the N_2O gas emitted was approximately 17% of the total nitrogen applied. A large water flux in soil was observed during a thawing period in the early spring. Since soil water content affected the N_2O gas emission, further research is needed to understand the relationship between the freezing and thawing of soil and the emission of the greenhouse gases. A two-dimensional fully-coupled water, solute, and heat transport model was developed. We should consider the effect of animal manure on both water and atmospheric environments when we establish management practices for animal manure application to an agricultural field. Less