Spatial variability and drivers of N2O emission responses to nitrogen fertilization across agricultural regions in China

Abstract

Nitrogen fertilization is an important source of agricultural N 2 O emissions, yet the spatial variability in nitrogen-induced N 2 O responses and its underlying drivers across agricultural regions in China remain insufficiently understood. This study conducted a meta-analysis of 462 independent field observations from 83 studies to quantify the responses of cropland N 2 O emissions to nitrogen fertilization across seven agricultural regions in China and to examine the associated environmental and management factors. Nitrogen fertilization significantly increased N 2 O emissions, with a pooled lnRR of 1.22 (95% CI: 1.08–1.36), corresponding to a 237.8% increase relative to unfertilized controls, while substantial heterogeneity was observed among observations. The magnitude of N 2 O responses differed significantly among agricultural regions, with the highest response in the Huang-Huai-Hai Plain (lnRR = 1.63) and the lowest in the Northern arid and semiarid region (lnRR = 0.86), although substantial heterogeneity remained within regions. Subgroup analyses indicated that nitrogen application rate, fertilizer type, cropping system, precipitation, temperature, and soil texture were associated with differences in N 2 O responses. In multivariable meta‑regression, nitrogen application rate exhibited a significant nonlinear association with N 2 O responses, while significant interactions among nitrogen application rate, soil pH, precipitation, and fertilizer type suggested that N 2 O responses were jointly modulated by environmental and management conditions rather than driven by independent main‑effect controls. These findings suggest that agricultural regionalization can capture broad-scale spatial differentiation in nitrogen-induced N 2 O responses, yet substantial within‑region heterogeneity highlights that agricultural regions should not be treated as homogeneous response units, and local environmental and management conditions must be considered when assessing these responses.

The authors' abstract, as published at the source. Agricultural Water Management, 2026 · DOI ↗