Study On Synergistic Mechanism Of Different Urease Inhibitor And Nitrification Inhibitor Combinations

Nitrogen plays an important role in improving the yield and quality of crops,but nitrogen has volatilization,leaching and denitrification losses in the soil,resulting in low nitrogen utilization.At present,nitrogen fertilizer combined with biochemical inhibitors can effectively control nitrification in soil,thus reducing nitrogen loss,improving nitrogen fertilizer utilization and increasing crop yield.At present,there are a lot of studies on the effects of single nitrification inhibitor and urease inhibitor,but the results are not good.Therefore,some researchers have carried out research on the combination of biochemical inhibitors,but nowadays there are not many studies on the combination of biochemical inhibitors,and the results are not the same.The effect in the brown soil area of northeast China needs to be further studied.By different dosage of single biochemical inhibitors?DMPP,DCD,NBPT,calcium salt?and different biochemical inhibitors combination of indoor thermostatic cultivation test,the determination of soil ammonium nitrogen,nitrate nitrogen,urease activity,nitrification potential and p H,preliminary screening has a better effect on brown soil biochemical inhibitors and combination.Then the pot experiment of maize was conducted to determine the ammonium nitrogen,nitrate nitrogen,urease activity,nitrification potential,basic physical and chemical properties of soil,total nitrogen,total phosphorus,total potassium,biomass and yield of maize in different growth periods of maize,so as to select the optimal combination of biochemical inhibitors.In order to provide scientific basis for efficient management and environmental protection of nitrogen fertilizer in brown soil area,the aim of reducing weight and increasing efficiency was achieved by reducing fertilizer consumption.The main findings are as follows:?1?Compared with urea-only treatment,adding a single biochemical inhibitor to long-term non-fertilized soil and long-term organic fertilizer application soil can delay the oxidation of NH₄⁺-N,reduce the content of NO₃^--N in the soil,reduce the p H drop caused by nitrogen application,and reduce the soil nitrification potential.DCD and DMPP had the best inhibitory effect in both treatments.The overall inhibitory effect trend was as follows:5%DCD>2%DCD>1%DCD>N;2% NBPT NBPT > 1% > 0.5% NBPT > N,DMPP 2% > 1%DMPP DMPPP > 0.5% > 0.1% DMPP > N.20% calcium salt >10%,5% Ca,N.?2?Compared with urea-only treatment,the addition of a combination of inhibitors to soil with long-term non-fertilization and long-term application of organic fertilizer can significantly inhibit the transition from ammonium nitrogen to nitrate nitrogen.DCD+DMPP treatment and Ca+DMPP treatment had better inhibitory effects in both treatments.The urease activity of DCD+DMPP treatment and Ca+DMPP treatment in the first 21 days of culture was significantly higher than that of urea-only treatment,and the urease activity of all combination treatments after 21 days of culture was significantly lower than that of urea treatment alone.?3?The results of the pot experiment showed that the content of ammonium nitrogen in the soil and cumulants of N,P,K of maize were significantly increased,while the content of nitrate nitrogen and the nitrification potential were significantly decrease in all treatments with addition of biochemical inhibitors.However,there are no significant difference between contents of available phosphorus and available potassium in all treatments.Compared with the N1 PK treatment,nitrogen use efficiency,biomass and yield of maize were improved in treatments with addition of biochemical inhibitors except the N1 PKDP treatment.Effects of inhibitors was the most obvious in N1 PKCP,N1PKP and N1 PKD treatments,the nitrogen use efficiency in which was increased 5.02%,4.60% and 4.59%,respectively;the Nitrogen partial factor productivity in which was increased 4.52%?4.08%?4.13%,respectively;the percentage of maize biomass in which was increased 16.28%,16.53% and 15.67%,respectively;and the yield was increased 21.52%,19.45% and 19.67%,respectively.The application of biochemical inhibitors to nitrogen fertilizer in brown soil can significantly reduce the nitrification potential of soil,increase the absorption and accumulation of nitrogen,phosphorus and potassium in maize,improve the nitrogen use efficiency and increase the yield of maize.In the culture experiment,although the combination of DCD,DMPP and calcium salt inhibitor had better effect than the corresponding single inhibitor with the same dosage,the application effect of nitrogen fertilizer combined with biochemical inhibitor was not necessarily better than that of single biochemical inhibitor in the pot experiment.Therefore,only after the screening of specific soil types can the combination of effective biochemical inhibitors be obtained to achieve the best stimulation effect.