资源环境科技发展态势分析平台

Soil emissions represent similar to 25% of the global annual atmospheric budget of nitrogen oxides (NOx). The nitrogen isotopic composition of soil NOx emissions (delta N-15-NOx) is potentially useful to track soil emission contributions to NOx budgets, yet its in situ variations with fertilizer management and meteorology are unknown. We quantify in situ delta N-15-NOx distributions from liquid dairy manure-fertilized cropland in State College, Pennsylvania at hourly resolution during spring 2016 and 2017.delta N-l5-NOx(n = 37) ranged from -44.2 to -14.0 parts per thousand and was distinct between injected (-32.2 +/- 12.1 parts per thousand) and broadcast manure without tillage (-23.4 +/- 2.1 parts per thousand). delta N-15-NOx was not correlated with order of magnitude emission variations due to large changes in soil moisture. delta N-15-NOx differences between treatments were associated with nitrification and NO consumption contributions. Our results suggest that delta N-15-NOx can be a valuable observational tracer of soil emissions and varies with fertilizer management practices.

Plain Language Summary Soil processes contribute about one quarter of all global emissions of nitrogen oxides, with important impacts on air quality and ecosystem health. The ratios of heavier to lighter nitrogen atoms (isotopes) are potentially useful to track soil emissions, but it is uncertain how they vary with agricultural management choices and weather conditions. We measure isotopes of soil nitrogen oxides emitted from manure-fertilized cropland and find large differences based on whether manure was injected below or applied onto soil surfaces. Our results provide a new potential way to track agricultural emissions and their impacts on air pollution and ecosystem health.