Global analysis of nitrification inhibitors on grasslands nitrous oxide emission rates

Abstract

Field studies have tested the effectiveness of nitrification inhibitors in reducing grassland soil nitrous oxide (N2O) emissions. However, the magnitude of the effects on N2O emission rates across global grasslands remains unclear owing to its spatial heterogeneity. In this study, we synthesized 40 datasets from 23 published studies. The meta-analysis revealed that effect size of nitrification inhibitors was −0.59 ± 0.07 (95% confidence interval: −0.73 to −0.46). The mitigation effect on global grassland N2O emission rates was approximately 44.56%. Meanwhile, dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) decreased grassland N2O emission rates by 48.31% and 32.97%, respectively (P < 0.05). The mixed effects models indicated that total nitrogen, soil bulk and air temperature were the main controlling factors, which explained 42.79%, 40.70%, and 18.59% of the variation in effect size, respectively. Considering global warming, there is considerable potential benefit from mitigating grassland N2O emissions through the application of DCD and DMPP.