Urea ammonium nitrate solution combined with urease and nitrification inhibitors jointly mitigate NH3 and N2O emissions and improves nitrogen efficiency of summer maize under fertigation

The application of nitrogenous fertilizer synergist to coordinate nitrogen transformation process in soil may be an efficient strategy to increase nitrogen use efficiency and decrease environmental pollution. However, there are few reports on the application effects of UAN synergistic nitrification and urease inhibitors under the integration of water and fertilizer. This study aimed to explore effects of urea ammonium nitrate solution (UAN) combined with urease and nitrification inhibitors on yield and nitrogen efficiency of summer maize and its ecological effects under the fertigation, and to provide scientific basis for the efficient utilization of UAN. The experimental treatments were as follows: no inhibitor treatment (U), nitrification inhibitor treatment (U-D), urease inhibitor treatment (U-N), and the combination of nitrification and urease inhibitors treatment (U-D+N). Results showed that UAN combined with urease or nitrification inhibitors could significantly reduce the cumulative emission of N2O, and then significantly decreased the N2O warming potential (GWPN2O) and N2O greenhouse gas intensity (GHGIN2O). Compared with U treatment, the cumulative N2O emissions of U-D+N, U-N, and U-D treatments was reduced by 45.7 %, 25.3 % and 35.8 %, respectively. The GWPN2O of U-D+N, U-N and U-D treatments decreased by 45.7 %, 25.3 % and 35.7 %, while GHGIN2O decreased by 50.9 %, 30.3 % and 38.9 % on average, respectively, compared to those of U treatment. Application of urease inhibitors significantly reduced NH3 volatilization. The cumulative NH3 volatilization of U-N and U-D+N treatments was reduced by 30.7 % and 23.4 %, while U-D treament was significantly increased by 12.3 %, respectively, compared to that of the U treatment. In addition, UAN combined with urease or nitrification inhibitor could significantly increase the contents of NO3--N and NH4--N in the 0–20 cm soil layer, and significantly reduced the leaching of NO3--N to the deep soil. The total nitrogen accumulation, grain nitrogen content, nitrogen transport efficiency and post-anthesis assimilation of summer maize were significantly increased, which were beneficial to the improvement of grain yield and economic benefits. under the fertigation, the synergistic application of UAN with urease and nitrification inhibitors were beneficial to reduce greenhouse gas emissions and ammonia volatilization, improved the nitrogen use efficiency, and then improved the yield and economic benefits of summer maize. Under the fertigation, UAN combined with urease and nitrification inhibitors were beneficial to emission reduction, high yield, and high efficiency.