秸秆还田提高玉米产量阻控土壤氮素流失的作用机制OA

[Objectives]The regional effects of straw return on maize yield,nitrogen(N)uptake,soil N leaching and runoff in China and its dominant driving factors were studied,so as to provide a scientific basis for the rational application of straw return.[Methods]A total of 1775 valid observations were collected from 97 published articles in which field experiments were conducted in China across 1990-2023.Meta-analysis and random forest modeling was employed to quantify the effects of straw removal vs.straw return on maize yield,N uptake and N transport in soil profile(0-20 cm,20-40 cm,40-60 cm)under contrasting management practices and climatic conditions.The variation characteristics of soil N leaching and runoff losses were dissected,and their dominant driving factors were analyzed.[Results]Compared to straw removal,straw return significantly increased maize yield by 7.9%and N uptake by 10.1%.In the 0-20 cm layer,soil nitrate-N(NO3--N),ammonium-N(NH4+-N)and total N(TN)contents rose by 19.8%,7.3%and 11.7%,respectively.Across the 20-40 cm profile,NO3--N and TN increased by 20.0%and 13.3%,whereas NH4+-N had no significant difference between the two treatments.In the 40-60 cm horizon,TN still increased by 9.3%.Straw return reduced TN leaching and runoff losses by 21.3%and 21.8%,respectively.Random-forest analysis identified initial soil TN,soil organic C(SOC)and pH as the dominant drivers of maize yield,whereas N uptake was primarily driven by water management and soil NH4+-N.In the 0-20 cm layer,initial SOC(contribution rate 23.0%)and initial TN(contribution rate 21.4%)were the principal factors regulating NO3--N content,NH4+-N was most strongly influenced by soil initial TN(contribution rate 19.4%),and surface TN was regulated by initial TN(contribution rate 34.6%),pH(contribution rate 31.3%)and initial SOC(contribution rate 30.6%).In the 20-40 cm layer,mean air temperature during the growing season(contribution rate 16.6%),soil texture(contribution rate 16.6%)and N fertilizer rate(contribution rate 24.3%)were the key drivers of NO3--N,NH4+-N and TN,respectively.In the 40-60 cm layer,mean air temperature(contribution rate 21.8%)and precipitation(contribution rate 13.0%)during the growing season predominantly governed NO3--N and NH4+-N,whereas TN was jointly controlled by precipitation(contribution rate 21.7%)and temperature(contribution rate 18.6%)and N fertilizer rate(contribution rate 18.2%).[Conclusions]Returning straw significantly increased maize yield and N uptake while reducing soil N leaching and runoff losses in China.The initial soil total N,SOC content,and pH were crucial factors influencing the yield response to straw return.Water management and initial NH4+-N were the primary drivers affecting N uptake.In soils with high total N content,moderate to low organic C levels,and slightly acidic pH,straw return substantially enhanced maize yield potential.Additionally,integrating straw return with deep plowing,irrigation,and optimized N fertilizer application significantly mitigated the downward leaching potential of N within the plough layer.Mean air temperature and precipitation during the growing season were identified as the major drivers regulating deep soil NO3--N and NH4+-N dynamics.