Mitigating greenhouse gas emissions in water-limited agroecosystems by novel integration of perennial grasses

Climate change and variability have severely impacted agriculture in arid and semi-arid regions. It calls for innovations in agriculture to enhance soil health, increase water use efficiency, and mitigate soil organic matter and nutrient loss while sustaining crop production. This study investigated how integrating innovative circular buffer strips of native perennial grasses with row crop strips minimizes soil greenhouse gas (GHG) emissions and the factors driving these emissions. Soil carbon dioxide (CO2) and nitrous oxide (N2O) fluxes were measured weekly over two years in plots under buffer strip grass (BSG), buffer strip corn (BSC), and continuous conventional corn (CCC) without grass buffers. Average soil N2O fluxes from BSG were 23.9-53.1% lower than corn fields (BSC and CCC), resulting in a 34.1-45.5% reduction in cumulative N2O emissions. Similarly, BSG had 36.9-51.3% lower cumulative CO2-C emissions than corn fields. Among corn fields, BSC emitted 22% less CO2-C and 22.3% less water-normalized CO2-equivalent emissions than CCC. The crop phase accounted for ∼90% of total CO2 and ∼63% of total N2O emissions, suggesting that CO2 emissions are more closely associated with plant growth, while winter fluxes are crucial for accurate N2O estimates. Evaluation of factors driving GHG emissions using random forest models showed that it describes 70% and 30% variability in CO2 and N2O emissions, respectively. Soil temperature was the primary driver of CO2 and N2O emissions, followed by inorganic N and soil water content. Integrating perennial grass strips can reduce GHG emissions in semi-arid cropping systems by moderating soil and microclimatic conditions.