Research On Inhibitor And Biochar To Resist And Control Nitrogen Leaching From Biogas Slurry Irrigation

At present,as the organic fertilizer with excellent development prospect,the biogas slurry is broadly used in agricultural production,but it’s the fertilizer of inorganic nitrogen mixed with organic nitrogen;the irrigation method of much water and fertilizer easily causes the leaching of soil nitrogen,it leads to the pollution of water environment,so the issues of nitrogen leaching brought by biogas slurry irrigation need to be urgently solved.Three groups of test are totally set in the research through earth pillar simulation leaching device.Under biogas slurry irrigation,ammonium nitrogen(NH4+-N),nitrate nitrogen(NO3--N),total nitrogen(TN),and dissolved organic carbon content(DOC)in the soil leaching solution were monitored for five continuous irrigation cycles in every test.It is separately discussed that the nitrogen leaching resistance and control effect of nitrification inhibitor type and dosage,resistance control effect of nitrification inhibitor(DCD and CP)mixed with urease inhibitor(NBPT and HQ)and biochar(B),the inhibitory effect is verified by the technical mode of optimized leaching resistance control under different irrigation intensity of biogas slurry so as to provide theoretical basis for the safe and valid utilization of biogas slurry.The main results were as follows:1.The application of biogas slurry reduces the risk of carbon and nitrogen leaching.Biogas slurry single application significantly reduced carbon and nitrogen leaching concentrations and leaching losses compared to urea solution and ammonium sulfate solution.The concentrations of TN,NH4+-N,NO3--N,and DOC in leachate in DCD group were reduced by 27.2%,35.7%,45.9%,53.7%,and in Nitrapyrin group by 24.9%,30.9%,21.1%,64%,respectively,with 5%level of significance for various treatments.2.Nitrification/urease inhibitor combination as well as the combination mode with biochar can effectively inhibit the nutrition leaching and improve nitrogen utilization,which is the valid measure to resist and control the leaching pollution of soil nitrate.Compared with single application of biogas slurry,the combination of DCD+HQ,DCD+NBPT,CP+HQ and CP+NBPT can obviously reduce the leaching of TN,NH4+-N,NO3--N and DOC in leaching solution,which averagely reduce 30.6%,54.1%,37.1%and 22.3%;the leaching of TN,NH4+-N,NO3--N in DCD+HQ+B,DCD+NBPT+B,CP+HQ+B and CP+NBPT+B treatment leaching solution averagely reduce 45.2%,34%and 48.3%,but the leaching risk of DOC increases.From the perspective of nitrogen leaching inhibition,DCD+HQ+B and CP+NBPT+B can be used for the optimized resistance control mode.3.The risk of soil nitrogen leaching is bigger if the irrigation intensity of biogas slurry is stronger.The CP+NBPT+B combination mode in the test mixed with increased 30%,60%and 100%irrigation amount in soil biogas slurry still has the inhibition effect on the leaching of NO3--N and TN,NO3--N separately reduces 59.3%,55.1%and 46.6%;TN separately reduces 31.7%,27.1%and 15.4%.