Applying urea ammonium nitrate solution saves nitrogen resources by changing soil microbial composition under micro sprinkling fertigation: an effective nitrogen management practice

Abstract

ContextHow to improve nitrogen (N) efficiency and reduce environmental pollution caused by N loss has attracted much attention. However, limited research has lacked a comprehensive exploration of the effects of applying UAN under the micro sprinkling fertigation on reactive N (Nr), fertilizer efficiency and net benefits including environmental costs, plus associated responses of the microbial metagenome. ObjectiveThe aim of this study was to assess the impact of N management practices on maize yield, Nr losses, and soil microbial community composition and function. MethodsUrea and urea ammonium nitrate solution (UAN) were used as N sources, and three N application rates (210, 168 and 0 kg N ha−1) and two fertilization methods (micro sprinkling fertigation and traditional fertilization) were set as the three key components. ResultsThe results showed that micro sprinkling fertigation treatments reduced Nr losses, increased yield and N efficiency. Compared with urea, the total NH3 volatilization and N2O emissions of UAN under micro sprinkling fertigation were decreased by 14.8% and 30.6%, respectively. Furthermore, the N reduction (FU1) treatment promoted plant N uptake, was saved 20% of N by affecting soil NH4+- N and NO3--N content, compared to that of urea, and it regulated the microbial abundance of N cycle function related to denitrification and N respiration, reduced global warming potential and greenhouse gas emission intensity. ConclusionsN application method, N source and N rate affected the diversity and composition of soil bacterial community, and altered Nr emissions by changing the abundance of functional microorganisms related to N cycle. Overall, improved N management practice was more conducive to increasing maize yield and net income, saving N resources, and reducing the risk of environmental damage. SignificanceOur results contribute to a comprehensive understanding of the impact of N management on summer maize production, providing an effective N management practice that is conducive to “green agricultural development”.