Soil emissions represent ~25% of the global annual atmospheric budget of nitrogen oxides (NOx). The nitrogen isotopic composition of soil NOx emissions (δ15N-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 δ15N-NOx distributions from liquid dairy manure-fertilized cropland in State College, Pennsylvania at hourly resolution during spring 2016 and 2017. δ15N-NOx (n = 37) ranged from −44.2 to −14.0‰ and was distinct between injected (−32.2 ± 12.1‰) and broadcast manure without tillage (−23.4 ± 2.1‰). δ15N-NOx was not correlated with order of magnitude emission variations due to large changes in soil moisture. δ15N-NOx differences between treatments were associated with nitrification and NO consumption contributions. Our results suggest that δ15N-NOx can be a valuable observational tracer of soil emissions and varies with fertilizer management practices.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)