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

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 NH3emissions,N2O emissions,winter wheat yields,yield-scaled NH■3,and yield-scaled N2O ■.Five treatments were investigated,no nitrogen (N) fertilizer (N0),U application at 150 kg N ha–1with and without SI (SI+U and S0+U),and PCU application at 150 kg N ha–1with and without SI (SI+PCU and S0+PCU).The results showed that the NH3emissions increased by 20.98–34.35%following SI compared to straw removal,mainly due to increases in soil ammonium (NH+4-N) content and water-filled pore space (WFPS).SI resulted in higher N2O emissions than under the S0scenario 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 ■ 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 Nemissions and maintaining optimal winter wheat yields in Northwest China.