Controlled Irrigation Combined with Powdered Straw Return Mitigates Greenhouse Gas Emissions While Enhancing Soil Fertility and Economic Benefits

Aims To address the limitations of conventional segmented straw burial methods, which may disrupt crop root systems and hinder field operations, an innovative straw powder incorporation technique has been developed. This approach involves processing straw into fine powder form for uniform field application, with the objectives of achieving three key benefits: significant reduction in paddy field greenhouse gas emission intensity, improvement of soil nutrient availability, and enhancement of crop yield potential. Methods A two-year pot experiment was conducted to evaluate the effects of frequent shallow irrigation (FSI) and controlled irrigation (CI) combined with fragmented straw (D) and powdered straw (F) on methane (CH₄) and nitrous oxide (N₂O) emissions in rice cultivation. Results The findings indicate that Straw return under all irrigation methods increased soil organic carbon (SOC) content. Notably, CI+F achieved the highest SOC enhancement, rice yield, economic benefits, and the lowest greenhouse gas (GHG) emissions among all treatments. Compared to CI+F, CH₄ emissions were 38.59%, 86.31%, and 67.13% higher in FSI+F, FSI+D, and CI+D, respectively (two-year average), Corresponding global warming potential (GWP) increased by 36.97%, 83.43%, and 65.36%. Rice yield in FSI+F showed no significant difference from CK, whereas FSI+D reduced yield by 3.29%-4.68%. In contrast, CI+F increased yield by 8.02% to12.84% over other treatments. FSI elevated CH₄ emissions and GWP relative to CI. Conclusion Powdered straw outperformed fragmented straw in yield enhancement and emission reduction. Therefore, CI with powdered straw return is an effective approach to ensure increased yield, reduced emissions, and enhanced profitability in paddy fields.