Effects Of Urea Application Combined With Slow Release Fertilizer On Summer Maize Growth And Utilization Of Water And Nitrogen

Research under different N levels of urea and slow-release nitrogen fertilizer mixing with urea on summer maize growth,yield,nitrogen absorption and utilization,the influence of soil NO₃^--N residue,in order to obtain increase crop yield,improve the Nitrogen utilization rate and decrease soil NO₃^--N leaching of nitrogen efficient optimum fertilization method.The summer maize‘Zhengdan 958’was selected for the experiment.Six nitrogen fertilizer types（C:slow-release urea,U2C8:a mixture of conventional urea and slow-release fertilizer with N ratio 2:8,U3C7:a mixture of conventional urea and slow-release fertilizer with N ratio 3:7,U4C6:a mixture of conventional urea and slow-release fertilizer with N ratio 4:6,U5C5:a mixture of conventional urea and slow-release fertilizer with N ratio 5:5,U:conventional urea）.Two levels of nitrogen were applied in the growth period of summer maize.N1（180 kg/hm²）and N2（120 kg/m²）were applied to the study.We designed a plot received no nitrogen for the control（CK）.A total of 13 experimental treatments were performed.In the growing period of summer maize,the growth indexes of the plants were observed,and the yield,yield components,plant nutrients and soil nitrate nitrogen contents in each growing period were counted.The test results are as follows:（1）The addition of urea and slow-release fertilizer can promote the growth of summer maize in the middle and late stage,but excessive nitrogen application will inhibit the growth of summer maize.Under the condition of the same proportion of slow-release fertilizer,the plant height,stem diameter and leaf area index of each treatment with nitrogen application level of 180 kg/hm² were all higher than that of each treatment with nitrogen application level of 240kg/hm².Under the same nitrogen application level,after jointing stage,plant height,stem diameter and leaf area showed a trend of first increase and then decrease with the increase of urea sustained-release fertilizer blending ratio,and the growth indexes under U3C7 treatment all reached the maximum.The most favorable nitrogen fertilizer for summer maize growth was 180 kg/hm² of nitrogen application level,and the mixing ratio of urea slow-release fertilizer was 3:7.（2）Excessive nitrogen application can reduce the accumulation of dry matter in over ground parts in the mature stage.Under the same mixing ratio,the dry matter accumulation amount of over ground part was higher than that of 240 kg/hm² under the condition that the nitrogen fertilizer dosage was 180 kg/hm².Under the same nitrogen application level,after silking stage,summer maize leaf area index first increased and then decreased with the increase of urea sustained-release fertilizer proportion,and the leaf area index under U3C7treatment was the largest.In the upper part of the summer maize field,the optimum level of dry matter accumulation was 180 kg/hm²,and the ratio of urea slow-release fertilizer to fertilizer was 3:7.（3）Urea sustained release fertilizer can effectively increase the yield of summer maize.Under the same ratio,the yield and composition index of each treatment at the nitrogen application level of 180 kg/hm² were all higher than that at the nitrogen application level of240 kg/hm².Excessive nitrogen application would lead to a decline in the yield of summer maize.However,with the same amount of nitrogen,the yield and its component index showed a trend of increasing first and then decreasing with the increase of urea sustained release fertilizer admixture ratio.The yield and its component index of U3C7 treatment were higher than those of other admixture treatments.The optimal nitrogen fertilizer to increase the yield of summer maize was 180 kg/hm²,and the ratio of urea sustained-release fertilizer was 3:7.（4）N will significantly increase the amounts of accumulated nitrogen summer maize mature organs,organs for nitrogen accumulation in grains>leaf>stem>cob bracts,slow-release urea fertilizer mixing than single application of slow release fertilizer and urea high amounts of accumulated nitrogen each organ,excessive nitrogen can reduce the amounts of accumulated nitrogen organs,under the same n application rate of nitrogen accumulation of different organs U3C7 processing quantity highest,with the increase of mixed give than the amounts of accumulated nitrogen organs showed a trend of decrease after the first increase.The most favorable nitrogen application amount for nitrogen accumulation in all organs in the mature stage of summer maize was 180 kg/hm²,and the ratio of urea sustained release fertilizer was 3:7.（5）The application of slow release fertilizer can significantly improve the summer corn n accumulation amount,nitrogen uptake efficiency and n utilization efficiency,nitrogen use efficiency and nitrogen harvest index,the index value of excess nitrogen can reduce instead,under the same n application rate U3C7 treatment of each index is the largest,as the growth of the mixed give than n accumulation amount,nitrogen uptake efficiency and n utilization efficiency,nitrogen use efficiency and nitrogen harvest index showed a trend of decrease the increase then.The most beneficial nitrogen application amount for improving nitrogen accumulation,nitrogen absorption efficiency,nitrogen utilization rate,nitrogen fertilizer utilization rate and nitrogen harvest index of summer maize was 180 kg/hm²,and the ratio of urea sustained release fertilizer was 3:7.（6）Applying slow-release fertilizer could improve nitrogen utilization of summer maize,reduce soil NO₃^--N leaching,n application rate of 180 kg/hm² when more than 240 kg/hm²is beneficial to reduce nitrogen leaching,with the improvement of the urea slow-release fertilizer mixing give than,mature period the residues of soil NO₃^--N showed increasing trend after reducing,then U3C7 processing of mature period of residual soil NO₃^--N lowest,filling stage and mature surface soil NO₃^--N content of soil NO₃^--N accumulation amount the highest percentage,fully demonstrated U3C7 treatment can effectively reduce the soil nitrogen leaching,the most beneficial to crop root system to absorb nitrogen,Therefore,the ratio of urea sustained-release fertilizer to nitrogen utilization is 3:7.（7）Urea slow-release fertilizer mixing can improve water use efficiency,at the same ratio of urea sustained release fertilizer,the water use efficiency of 180kg/hm² was higher than that of 240kg/hm²,with the increase of urea sustained-release fertilizer admixture ratio,the water use efficiency of summer maize increased first and then decreased.U3C7treatment has the highest water use efficiency,the ratio of urea sustained-release fertilizer to water use efficiency was 3:7.