Effects of Fertilization and Wheat Straw Management on Rice Yield and Potential Pollutant Emissions in Paddy Fields

Environmental pollution caused by excessive nitrogen fertilization has become increasingly serious, making optimized fertilization and straw management critical for improving agricultural sustainability.This study involved a two-year field trial with three fertilization treatments: conventional fertilization (CF), 23.5% nitrogen reduction (RCF), and 23.5% nitrogen reduction with 20% organic fertilizer substitution (OF). Additionally, three straw management practices were tested: straw removal with shallow tillage (SRS), straw incorporation with shallow tillage (conventional straw management practice,SIS), and straw incorporation with deep plowing (SID). The effects of these treatments on rice yield, pollutant emissions, and soil quality were systematically assessed.The results indicate that, under the same straw management practice, RCF and OF can maintain stable rice yields compared to CF. Under the same fertilization scheme, SID increased yield by 0.41%-2.61% by enhancing panicle number, grain number per panicle, and 1000-grain weight.In terms of environmental effects, compared to CF, RCF reduced AUC-NH4+-N by 19.39%-23.40%, and AUC-NO3--N by 10.72%-12.77%, while OF reduced AUC-TP by 71.01%-74.25%.Under conventional straw management practice (SIS), OF reduced cumulative methane emissions by 22.06%-28.81% compared to CF, and under conventional fertilization (CF), SID reduced cumulative methane emissions by 19.50%-21.31% compared to SIS.In terms of soil quality, nitrogen reduction alone (RCF) decreased soil organic carbon (SOC) and total nitrogen (TN) content, while organic fertilizer substitution (OF) increased SOC by 7.84% and TN by 4.47% at maturity under the SIS treatment.Under the CF treatment, SID increased soil SOC by 4.96% and TN by 2.23% at maturity compared to SIS.Overall, a strategy combining 23.5% nitrogen reduction with 20% organic fertilizer substitution and deep straw incorporation maintained rice yield while reducing pollution risks and improving soil fertility, representing an optimized agronomic practice for rice–wheat rotation systems.