Applicability Of Slow And Controlled-relese Fertilizer On Spring Maize Under Plastic Mulching Cultivation Mode In Arid Area Of Northwest China

In order to study the yield and income increase and environmental effects brought by plastic film mulching combined with slow and controlled release fertilizer in arid and semi-arid areas of northwest China,spring maize was selected as the experimental object in this study,and two main treatments were set up in split area experiment:black plastic film mulching and white plastic film mulching:eight side treatments were as follows:no nitrogen application（N₀）,farmer model(N₂₅₀),nitrogen reduction model(N₂₀₀),urease inhibitor NBPT type slow and controlled release fertilizer（NBPT）,nitrification inhibitor type slow and controlled release fertilizer（DMPP and DCD）,resin-coated urea（RCN）and sulphur-coated urea（SCN）.Systematic analysis of four northwestern provinces under plastic film mulching and slow controlled release fertilizer for spring maize yield,water use efficiency and nitrogen use efficiency（WUE）,were systematically analyzed in four regions of northwest China（Ningxia Hui Autonomous Region,Gansu Province,Shanxi Province and Qinghai Province）,in order to screen out the varieties and quantities of slow and controlled release nitrogen fertilizer suitable for spring maize in northwest arid regions.It provides theoretical guidance and technical support for saving fertilizer,increasing yield and increasing efficiency of spring maize in northwest arid region.The current research results are as follows:（1）Yield increased of Ningxia hui Autonomous Region,Gansu Province and Qinghai Province was better under white film mulching,while the yield increase of Yingxian in Shanxi was better under black film mulching than white film mulching.The yield and its yield components could be increased by reducing nitrogen by 20%and adding slow release nitrogen.In Ningxia,Gansu and Shanxi,nitrogen reduction treatments increased by 2.0-46.9%,2.6-48.6%and 10.1-32.3%,respectively,for two consecutive years.In Ningxia,urease inhibitor NBPT type slow and controlled release fertilizer treatment had the best yield increase effect,in Gansu and Qinghai,nitrifying DCD type slow and controlled release fertilizer treatment had the best yield increase effect,in Shanxi,resin coated urea RCN treatment had the best yield increase effect.（2）The water use efficiency of white film mulching was higher than that of black film mulching in Ningxia Hui Autonomous Region gansu Province and Qinghai Province.Under white film mulching,the water use efficiency of urease inhibitor NBPT type slow and controlled release fertilizer was up to 39%in Ningxia,while the water use efficiency of nitrifying DCD type slow and controlled release fertilizer in Gansu and Qinghai was up to21.6%and 20%,respectively,which increased by 64.5%,21.6%,34.1%and 32.3%compared with N200 treatment,respectively.For two consecutive years,the highest water use efficiency of RCN treatment was 41%and 33%,respectively,increased by 54.7%and 37.7%compared with N200 treatment,respectively..（3）Different fertilization treatments significantly affected soil NO₃^–-N distribution from2019 to 2020,and soil NO₃^–-N content increased first and then decreased in three stages of spring maize growth and development.The difference of NO₃^–-N concentration in 0-40 cm soil layer was larger than that in 40-100 cm soil layer.Soil NO₃^–-N mostly accumulated in 0-20 cm soil layer.The agronomic efficiency,partial nitrogen productivity,and apparent nitrogen use efficiency increased by 3.5-8.6%,2.3-9.6%,and 6.5-21.3%,respectively,compared with the farmer model.The results showed that slow and controlled release fertilizer could effectively reduce the leaching risk of nitrate nitrogen.（4）The economic benefits of slow and controlled release fertilizer in 2020 increased to varying degrees compared with that in 2019.The highest value of urease inhibitor NBPT slow and controlled release fertilizer in Ningxia white film mulching was 22,389 yuan/ha,18.4%higher than that in N250 treatment.Under white film mulching in Gansu and Qinghai,the highest value of nitrifying inhibited DCD slow and controlled release fertilizer treatment was18453 yuan/ha and 11609 yuan/ha,increased by 33.1%and 21.7%compared with N250treatment,and the highest value of RCN treatment under black film mulching in Shanxi was24703 yuan/ha.It indicates that continuous application of slow and controlled release fertilizer will increase income.In summary,under plastic film mulching cultivation,20%reduction in n combined with slow and controlled release fertilizer can ensure the yield of spring maize,reduce the leaching risk of nitrate nitrogen,improve water and nitrogen utilization of spring maize,increase economic benefits and save labor costs.Under the conditions of this study,it is suggested to choose white mulching film and apply urease inhibitor NBPT slow-release fertilizer in Ningxia.In Gansu and Qinghai,white mulching film was used and DCD type slow and controlled release fertilizer was applied.Shanxi black mulch film,with resin coated urea RCN.