Effects Of Drip Fertigation On Maize Growth And Nitrogen Use Efficiency In Hetao Irrigation District

At present,the irrigation district in He Tao has the problem of unreasonable utilization of water and fertilizer resources in the agricultural development,and the waste of water and fertilizer resources has become the main source of the agricultural source pollution of the river.Through corn test and theoretical analysis,the method of combining the experiment of drip irrigation with the theoretical data in two years of field film,there were different irrigation limits and different fertilizer rates.At the same time,control the frequency of different fertilization.The test set three irrigation water limits respectively（-20 kPa,W1;-30kPa,W2;-40 kPa,W3）and use tensiometer control.The fertilization level of 5 N-P2O5-K2O was set at the lower limit of each irrigation（F0^F5）,a small number of high frequency fertilization methods are used to fertilize water with water every time.Two different frequency control trials（3 fertilization and 6 fertilization）were set under W2F4 irrigation fertilization level.The influencing mechanism and coupling effects of different supply modes of irrigation and fertilization on water and nutrient migration in the dry matter accumulation,yield,soil nitrogen transfer in root zone,nitrogen absorption and soil ammonia volatilization and nitrous oxide emissions of corn were explored.Based on that,multivariate regression analysis was used to evaluate the high yield and high efficiency of maize,and to explore the optimal irrigation and fertilization mode of water fertilizer was put forward.The main results were as follows:1.The lower irrigation limit is-30kPa and the fertilizer amount is 216-97.2-54²70-121.5-67.5 kg/hm²,which has the best promoting effect on all maize fertility indicators.When the lower irrigation limit is-30 kPa the distribution of NO3--N in 0⁶0cm soil layer is the most uniform.When the lower irrigation limit exceeded-30 kPa and the fertilizer amount exceeded 270-121.5-67.5 kg/hm²,the increase effect of nitrogen accumulation in maize was not obvious or even inhibited.The lower limit of irrigation is-30 kPa and 216-97.2-54 kg/hm² of fertilization,which can maximize nitrogen absorption of maize,reduce nitrate nitrogen residue in soil,and reduce NH3 and N2O emissions in the environment.2.The lower irrigation limit is-30 kPa,the fertilizer amount is 162-72.9-40.5 kg/hm²,and the NPFP and NAE are the largest,averaging 116.305kg/kg and 40.6kg/kg.The lower irrigation limit is-30 kPa,and the fertilizer amount is between 216-97.2-54²70-121.5-67.5kg/hm²,with an average NRE of 77.815%.When the irrigation amount is 276.54²90.38mm,the fertilizer amount is（N）236.96²93.64 kg/hm²,（P₂O₅）106.63¹32.138 kg/hm²,（K₂O）59.24⁷3.41 kg/hm²,WUE,output and net income are the best.3.Under a small amount of multiple fertilization in drip irrigation,the cumulative amount of ammonia volatilization and nitrous oxide is exponentially related to the amount of nitrogen fertilizer applied,and increases significantly with the increase of fertilizer applied.If the fertilizer amount exceeds 216-97.2-54 kg/hm²,the gas nitrogen loss will increase significantly.A few times in the high frequency of fertilizing than with traditional low frequency time fertilization method can significantly improve the yield,the nitrogen uptake and water utilization rate of fertilizer,and reduce the nitrate nitrogen in the soil residues and losses of nitrogen gas emissions.