Soil nitrogen substrates determine global N2O emission more than climate and other soil properties

Abstract

Accurate estimation of N 2 O emission is one of the primary objectives to project the warming potential. However, the global patterns and main controlling factors of soil N 2 O emission remain elusive. We compiled a dataset with 6016 field observations from 219 articles and found that the averaged soil N 2 O emission rate was 1111.8 ± 26.59 μg N m-2 day-1. Soil N 2 O emission rates were significantly influenced by climatic factors (i.e. mean annual temperature), soil physical and chemical properties (e.g. pH, nitrate, ammonium, and total nitrogen), and microbial traits (microbial biomass nitrogen) at a global scale. The combined direct effects of soil nitrate, ammonium, and total nitrogen (combined standard coefficient = 0.45) accounted for the most variance of global soil N 2 O emissions (total standard coefficient = 0.84). This study highlights the critical roles of soil nitrogen substrates on N 2 O emission, which will be helpful to optimize the process-models on soil N 2 O emissions.