A combination of straw incorporation and polymer-coated urea offsets soil ammonia and nitrous oxide emissions in winter wheat fieldsOACSTPCD

The combined effects of straw incorporation(SI)and polymer-coated urea(PCU)application on soil ammonia(NH3)and nitrous oxide(N2O)emissions from agricultural fields have not been comprehensively evaluated in Northwest China.We conducted a two-year field experiment to assess the effects of combining SI with either uncoated urea(U)or PCU on soil NH3 emissions,N2O emissions,winter wheat yields,yield-scaled NH3(/NH3),and yield-scaled N2O(IN2O).Five treatments were investigated,no nitrogen(N)fertilizer(N0),U application at 150 kg N ha-1 with and without SI(Sl+U and S0+U),and PCU application at 150 kg N ha-1 with and without SI(SI+PCU and S0+PCU).The results showed that the NH3 emissions increased by 20.98-34.35％following SI compared to straw removal,mainly due to increases in soil ammonium(NH4+-N)content and water-filled pore space(WFPS).SI resulted in higher N2O emissions than under the S0 scenario by 13.31-49.23％due to increases in soil inorganic N(SIN)contents,WFPS,and soil microbial biomass.In contrast,the PCU application reduced the SIN contents compared to the U application,reducing the NH3and N2O emissions by 45.99-58.07 and 18.08-53.04％,respectively.Moreover,no significant positive effects of the SI or PCU applications on the winter wheat yield were observed.The lowest INH3 and IN2O values were observed under the S0+PCU and SI+PCU treatments.Our results suggest that single PCU applications and their combination with straw are the optimal agricultural strategies for mitigating gaseous N emissions and maintaining optimal winter wheat yields in Northwest China.