Effect of N stabilizers on fertilizer-N fate in the soil-crop system: A metaanalysis

Nitrogen (N) fertilizer stabilizers (including urease inhibitors (UI), nitrification inhibitors (NI) and double inhibitors (DI)) are promising tools to mitigate N pollution from agricultural production. For a better understanding of how N stabilizers impact on the fate of fertilizer-N, we conducted a comprehensive meta-analysis of data from experiments that used the 15N as a tracer to investigate the effects of N stabilizers on fertilizer-N recovery in the soil-crop system. We combined this with boosted regression tree (BRT) model analysis to further interpret the contribution of soil properties and experimental conditions. The dataset consisted of 72 papers (227 observations). Our results suggest that UI, NI and DI significantly enhanced the fertilizer-N uptake by the crop by 24.1, 10.5 and 47.6 %, respectively, the fertilizer-N retention in the soil by 5.8 % (UI) and 15.0 % (NI), and the fertilizer-N recovery in soil-crop system by 16.4, 10.2 and 27.5 %, respectively. On the contrary, the fertilizer-N loss is reduced by 32.9, 14.5 and 37.6 % for UI, NI and DI, respectively. Soil pH, organic matter content, inhibitor compound and nitrogen application rate were the most important explanatory variables for the impact of UI and NI amendments on fertilizer-N recovery. These findings have major implications for N stabilizer application strategies in agricultural systems, where an important consideration is the mitigation of potentially detrimental environmental consequences.