Study On Controlling Measures Of Nitrate Nitrogen Leaching In Soil Of Spring Maize On The Southern Loess Plateau

The application of nitrogen fertilizer has increased rapidly since the early 1980s.Relevant studies have shown that the amount of fertilization has a great impact on the accumulation of NO₃^--N in dry land,and the effect of NO₃^--N accumulation on 0-2 m soil layer is particularly prominent.In order to study the mechanism of nitrate nitrogen leaching and control in rain-fed agriculture areas in the southern Loess Plateau,the field experiment was carried out in the agricultural ecological test station of the Changwu Loess Plateau of Chinese Academy of Sciences.Through the N application rate gradient,reducing nitrogen,straw buried deep,adding nitrification inhibitors concentration,urea and slow-release fertilizer mixing proportion of research,analysis of the change of soil NO₃^--N content and spring maize growth situation under different factors,to investigate the effect of different factors on soil nitrate-N in spring maize field.The test results are as follows:1.Nitrogen fertilizer can increase the yield of maize in a certain range,reasonable application of nitrogen fertilizer can prevent the leaching accumulation of nitrate nitrogen.Under different nitrogen application conditions,the biomass and yield of spring maize increased with the increase of nitrogen fertilizer,but the yield of spring maize stabilized after the application of nitrogen fertilizer reached a certain amount.In this experiment,the yield of spring maize no longer increased when the amount of nitrogen fertilizer exceeded 200 kg N/hm².The content and accumulation of nitrate nitrogen within the range of 0-200cm in the soil profile at harvest time increased with the increase of N application rate,while N application rate is more than160 kg/hm²,0²00 cm soil NO₃^--N accumulation amount will generate jump,160kg/hm² nitrogen treatment of soil NO₃^--N accumulation amount increased only 10.69kg/hm² compared with no nitrogen treatment.The nitrogen content of the soil profile?0²00cm?treated with nitrogen 200 kg N/hm² treatment and 250 kg N/hm²treatment increased by 66.26 kg/hm² and 96.55 kg/hm² respectively.2.Reduced nitrogen application and deep burial of straw can increase the yield of spring maize to some extent,and reduce the leaching of nitrate nitrogen into the deeper layers of the soil.Under conventional cultivation conditions,the yield of reduced?CR1?treatment increased 1259.62 kg/hm² compared with the conventional?CON1?treatment,and the cumulative amount of nitrate nitrogen profiles?0²00cm?of CR1 treatment decreased by 25.73%compared with that of CON1 treatment.Under deep straw stalk condition,the yield of reduced?CR2?treatment increased2523.04 kg/hm² compared with conventional?CON2?treatment,and the cumulative amount of nitrate nitrogen profile?0²00cm?of CR2 treatment decreased by 25.24%compared with that CON2 treatment.In addition,the yield of CR2 treatment was increased by 2878.04 kg/hm² compared with CON1 treatment.The cumulative amount of nitrate nitrogen profile?0²00cm?treated by CR2 was reduced by 30.17%compared with CON1 treatment.It shows that reducing nitrogen application and deep burying of straw can reduce the leaching accumulation of nitrate nitrogen to a certain extent.3.The addition of different concentrations of nitrification inhibitors?DCD?has different effects on the yield of spring maize and soil nitrate-nitrogen leaching accumulation.The treatment of DCD added by four addition of nitrification inhibitors(CRN_1%,CRN_5%,CRN_10%,CRN_15%)was 1%,5%,10%,and 15%of the amount of nitrogen applied.Compared with the treatment without addition of nitrification inhibitor(CRN_0%),the addition of nitrification inhibitor treatment had a certain decrease,but there was no statistically significant difference?P>0.05?.The cumulative nitrate nitrogen in the profiles of 0–200 cm with four addition nitrification inhibitors were lower than those without the addition of nitrification inhibitors(CRN_0%),which were reduced by 55.85%,43.24%,22.78%,and 18.54%,respectively.This shows that nitrification inhibitors can inhibit the decomposition of urea to a certain extent and reduce the accumulation of nitrate nitrogen leaching.The inhibitory effect of nitrification inhibitors on the deep accumulation of nitrate in soil decreased with the increase of the concentration.In this experiment,when the addition concentration of nitrification inhibitor was 1%,its effect on the deep accumulation of nitrate nitrogen was the most significant.4.Under the same nitrogen application rate,the addition of slow-release fertilizer in urea can help to reduce the accumulation of nitrate-nitrogen leaching in the soil profile without reducing production.CRS1 treatment?35%urea?,CRS2 treatment?urea 50%?,and CRS3 treatment?urea 65%?yield less than CRS4 treatment compared to total urea treatment?CRS4?but was not statistically significant Sexual differences?P>0.05?.Compared with CRS4 treatment,the accumulation of nitrate nitrogen in CRS1,CRS2,and CRS3 within the range of 0²00 cm was lower than that of CRS4treatment.The cumulative amount of nitrate nitrogen in the range of 100²00 cm was significantly decreased,which was a drop of 60.81.%,64.97%,and 39.92%.This shows that the slow-release fertilizer can slow down the leaching of nitrate from the deep layer.