Can cropland management practices lower net greenhouse emissions without compromising yield?

Smart cropland management practices can mitigate greenhouse gas (GHG) emissions while safeguarding food security. However, the integrated effects on net greenhouse gas budget (NGHGB) and grain yield from different management practices remain poorly defined and vary with environmental and application conditions. Here, we conducted a global meta-analysis on 347 observation sets of non-CO2 GHG (CH4 and N2O) emissions and grain yield, and 412 observations of soil organic carbon sequestration rate (SOCSR). Our results show that for paddy rice, replacing synthetic nitrogen at the rate of 30%-59% with organic fertilizer significantly decreased net GHG emissions (NGHGB: -15.3 +/- 3.4 [standard error], SOCSR: -15.8 +/- 3.8, non-CO2 GHGs: 0.6 +/- 0.1 in Mg CO2 eq ha(-1) year(-1)) and improved rice yield (0.4 +/- 0.1 in Mg ha(-1) year(-1)). In contrast, intermittent irrigation significantly increased net GHG emissions by 11.2 +/- 3.1 and decreased rice yield by 0.4 +/- 0.1. The reduction in SOC sequestration by intermittent irrigation (15.5 +/- 3.3), which was most severe (>20) in alkaline soils (pH > 7.5), completely offset the mitigation in CH4 emissions. Straw return for paddy rice also led to a net increase in GHG emissions (NGHGB: 4.8 +/- 1.4) in silt-loam soils, where CH4 emissions (6.3 +/- 1.3) were greatly stimulated. For upland cropping systems, mostly by enhancing SOC sequestration, straw return (NGHGB: -3.4 +/- 0.8, yield: -0.5 +/- 0.6) and no-tillage (NGHGB: -2.9 +/- 0.7, yield: -0.1 +/- 0.3) were more effective in warm climates. This study highlights the importance of carefully managing croplands to sequester SOC without sacrifice in yield while limiting CH4 emissions from rice paddies.

Automated summary

Smart cropland management practices can effectively reduce greenhouse gas emissions while increasing crop yield, such as replacing synthetic nitrogen with organic fertilizer in rice paddies. However, intermittent irrigation may lead to increased emissions and decreased yield. Therefore, it is important to manage croplands carefully to sequester soil organic carbon, maintain yield, and control methane emissions effectively.