Nitrification and Urease Inhibitors Reduce the Stimulated Nitrous Oxide Emissions by the Freeze-Thaw Cycles

Most studies have demonstrated that nitrification and urease inhibitors can reduce soil nitrous oxide (N 2 O) emissions from nitrogen-fertilized farmland.However, few studies have examined the potential impacts of these inhibitors on semi-arid agricultural farmland in the presence of freeze-thaw (FT) cycles.The purpose of this study was to assess the efficacy of applying the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) and the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) to soil nitrogen transformation and studying N 2 O emissions through simulated indoor FT incubation to offer theoretical and technological guidance for mitigating nitrogen loss in semi-arid farmland.The results showed that urea with DMPP under freeze-thaw conditions significantly increased the inorganic nitrogen content of the soil, kept the ammonium nitrogen content of the soil at a high level, suppressed the net nitrification rate of the soil, and reduced the cumulative emission of nitrous oxide (N 2 O) in the soil by nearly 87.6% compared to CK. Urea incubation with NBPT under freeze-thaw conditions also significantly reduced fluxes and cumulative N 2 O emissions.Due to the dual inhibition of soil nitrification rate by DMPP/NBPT and the FT cycle, the addition of DMPP/NBPT during soil FT could alleviate soil N 2 O emission caused by the effect of the FT cycle after urea addition and reduce soil nitrogen loss.The results indicate that the application of DMPP/NBPT can effectively alleviate the irrigated silt soil N 2 O emission during the FT period.