Jiayi Zhao

Large nitrogen (N) losses during fertilization in agricultural production may result in energy wastage, soil and water contamination, and potentially influence crop development. Thus, with the help of a ¹⁵N-labeled tracer, we carried out a field monitoring analysis of NH₃ emissions in a long-term (9-year) conservation tillage agroecosystem of Mollisols in northeast China, in order to determine whether a no-tillage regime and four levels of stover mulching (0%, 33%, 67%, and 100%), combined with urease and nitrification inhibitors, could improve fertilizer utilization efficiency in agricultural systems by reducing ammonia volatilization. Our results showed that in comparison with ridge tillage, no-tillage with stover mulching levels of 33%, 67%, and 100% significantly reduced NH₃ emission rates and cumulative volatilization from 159.67 to 130.42 g N ha⁻¹ and ¹⁵N-NH₃ cumulative volatilization emission by 26% (on average). Furthermore, the application of urease and nitrification inhibitors significantly reduced ¹⁵N-NH₃ volatilization levels from 1.19 to 0.98 g N ha⁻¹. Our research results demonstrate that a long-term no-tillage regime and straw mulching can significantly reduce NH₃ volatilization in fertilizers. Furthermore, when combined with the use of urease and nitrification inhibitors, these practices further enhance the reduction in NH₃ volatilization. Although the volatilization of ¹⁵N-NH₃ is minimally studied in Mollisols, these findings provide a solid foundation for improving fertilizer utilization efficiency, reducing crop production costs and mitigating subsequent environmental pollution.