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

Abstract

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.

Global benefits of non‐continuous flooding to reduce greenhouse gases and irrigation water use without rice yield penalty

“…This implies that non‐continuous flooding practices over carbon‐rich soils helps realize a synergy of irrigation water reduction and while maintaining rice yield levels. However, yield losses were more likely to occur at larger UFR and over soils with higher BD and pH (Figure S7) (Shang et al, 2021). These findings highlight the importance of UFR in regulating CH 4 emissions, IRR, as well as rice yield, through interaction with climatic and edaphic conditions and other management practices.…”

Unexpected Parabolic Temperature Dependency of CH4 Emissions from Rice Paddies

“…Second, because warming shortens the duration of plant growth, selecting rice varieties with longer growth periods may offset the negative effect of warming on rice yields. Third, new rice cultivar breeding programs may help to improve resistance to abiotic and biotic stresses and reduce CH 4 emissions. − For instance, high-yielding rice cultivars can significantly reduce CH 4 emissions. , Finally, optimizing agronomic practices such as water, straw, and tillage management can also increase the rice yield while simultaneously reducing CH 4 emissions. − Thus, synchronizing adaptation and mitigation efforts can help to maintain the rice yield and curb CH 4 emissions from rice agriculture as the world continues to warm.…”

Technologies and perspectives for achieving carbon neutrality

“…Optimization of fertilizer and water use in croplands can greatly reduce GHG emissions in crop production systems. 115 New synthetic N fertilizer types, such as slow- and control-release N fertilizers, and N fertilizers with urease and nitrification inhibitors, need to be developed to enhance N use efficiency. 116 Better cropping systems, fertilization, and irrigation practices, and the use of advanced digital agriculture technologies, such as multi-sensor drone technology to allow farmers to manage crops, soil, fertilization, and irrigation more effectively and precisely, can reduce N fertilizer input and N 2 O emissions.…”