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

Area of Science:

• Agricultural Science
• Environmental Science
• Climate Science

Background:

• Cropland management practices significantly influence greenhouse gas (GHG) emissions and food security.
• Understanding the integrated effects of these practices on net greenhouse gas budget (NGHGB) and grain yield is crucial but complex.
• Environmental and application conditions cause variability in management practice outcomes.

Purpose of the Study:

• To conduct a global meta-analysis to assess the integrated effects of different cropland management practices on GHG emissions, NGHGB, soil organic carbon sequestration rate (SOCSR), and grain yield.
• To identify specific management strategies that can mitigate GHG emissions while maintaining or improving crop yield.
• To provide evidence-based recommendations for sustainable agriculture.

Main Methods:

• A global meta-analysis was performed using 347 observation sets for non-CO2 GHG (CH4 and N2O) emissions and grain yield.
• 412 observations were used to analyze soil organic carbon sequestration rate (SOCSR).
• Data were analyzed to determine the impacts of practices like organic fertilizer substitution, intermittent irrigation, straw return, and no-tillage on NGHGB, SOCSR, and yield.

Main Results:

• For paddy rice, replacing 30%-59% of synthetic nitrogen with organic fertilizer decreased NGHGB (-15.3 ± 3.4) and improved yield (0.4 ± 0.1 Mg ha⁻¹ year⁻¹).
• Intermittent irrigation increased NGHGB (11.2 ± 3.1) and reduced yield (-0.4 ± 0.1 Mg ha⁻¹ year⁻¹), with significant SOC sequestration reduction in alkaline soils.
• Straw return increased NGHGB in paddy rice (4.8 ± 1.4) in silt-loam soils, while it was effective in upland systems in warm climates via SOC sequestration.

Conclusions:

• Optimizing cropland management, such as using organic fertilizers in rice cultivation, can effectively reduce GHG emissions and enhance grain yield.
• Practices like intermittent irrigation can have detrimental effects on both GHG emissions and crop yield, particularly in certain soil types.
• Management strategies like straw return and no-tillage show promise for sequestering soil organic carbon in upland systems, especially in warmer climates, contributing to climate change mitigation.