Study On Nitrogen Transfer And Transformation Of Summer Maize Farmland Under Water And Nitrogen Regulation

North China plain,as an important one of the major grain producing areas of our country generally faced with high output corresponding to the plight of high investment,excessive application of fertilizer in the process of wheat and corn field planting crop yield to nitrogen utilization ratio is lower than similar foreign crops.Long-term excessive nitrogen fertilizer not only changed the nutrition of the soil structure,and increase the risk of leaching,so research of nitrogen migration in the process of transformation of grain production,efficient utilization is of great significance.This test in Shandong province irrigation test center,test was conducted in the period 2019-2020,set up the irrigation amount and N application rate of two factors:the 2019 test irrigation water two levels（I1）67.5 mm and 121.5 mm（I2）,N application three levels of 145 kg/hm²,195 kg/hm² and 245 kg/hm²,a total of 6 groups of processing（QI1N1,QI1N2,QI1N3,QI2N1,QIN2,QI2N3,note:Q on behalf of processing,2019）;Irrigation water is consistent with the2019,2020 N application test on the basis of optimizing the test range,in 2019 set up two level of 150 kg/hm² and 200 kg/hm²,a total of four groups of processing（HI1N1,HI1N2,HI2N1,HI2N2,note:H on behalf of processing,2020）;In addition to the two annual set blank processing irrigation water,applied amount of fertilizer 0 mm and 0 kg/hm²,all process are set up three groups repeat for two years.By analyzing the management of nitrogen into the farmland water in the soil,plant,atmosphere and leaching after migration effects between optimization than select a set of effective improve nitrogen utilization,reduce nitrogen loss of summer corn water and nitrogen management scheme,this paper concluded the main research results are as follows:（1）Two years summer corn farmland soil nitrogen distribution,level of the two kinds of irrigation,soil NO₃^--N、NH₄⁺-N content increases with the increase of N application;I2irrigation level,each dealing with changes in the soil NH₄⁺-N content I1 irrigation level,under the effect of jointing stage irrigation,the soil NH₄⁺-N downward migration,accumulation and enhanced reduced soil NH₄⁺-N saved the surface soil,treatment HI2N2 than HI1N2 ammonia volatilization loss reduce 20.17%.Summer maize growth period to drench filtrate of NH₄⁺-N concentration change trend and drench the concentration in the filtrate have almost the same change trend;Soil inorganic nitrogen losses are mainly composed of NO₃^--N,changes in the rain NH₄⁺-N concentration in the filtrate tube has NO₃^--N concentration in the filtrate change hysteresis phenomenon.（2）Under the condition of same irrigation water,summer corn seedling stage to optimize n application can significantly reduce the ammonia volatilization of soil loss,treatment HI1N1than HI1N2 ammonia volatilization loss reduce 36.04%;Can improve the irrigation water in a large extent,to accelerate the process of ammonia volatilization ammonia volatilization,shorten the time and reduce the volatilization loss.Through the Pearson correlation analysis,increasing nitrogen application more significant impact on soil ammonia volatilization flux and the relationship between the surface soil p H,ammonia volatilization flux dynamic change characteristics and surface soil ammonium nitrogen concentration change trend.（3）Summer maize ear length,ear rows,spike grain number,hundred grain weight between four yield components before and after two years almost consistent increase yield,processing HI2N2 by increasing ear grain number and hundred grain weight to achieve maximum output;Partial agriculture productivity,nitrogen use efficiency of nitrogenous fertilizer,nitrogen utilization efficiency and n harvest index between all decreased with increasing n application rate,increased with the increase of irrigation amount;When handling HI2N1,nitrogen partial agriculture productivity,nitrogen utilization efficiency,nitrogen utilization efficiency were60.24 kg/kg,37.18 kg/kg,44.76%the highest in the processing.（4）On summer corn plant organs ¹⁵N labeling nitrogen source were analyzed,and the applying as nitrogen content increased,gradually increased n uptake in different organs,jointing stage irrigation,which can improve the synergy of summer maize organs of nitrogen absorption efficiency,summer maize growth anaphase irrigation can promote the rate of nitrogen transport of grain;In jointing stage irrigation under the action of summer maize nitrogen uptake not only can improve,but also can reduce nitrogen loss,processing HI2N1compared with processing HI1N1,summer maize nitrogen uptake increased 15.62%,decreased soil residual nitrogen 11.85%,nitrogen loss reduce 8.77%;HI2N2 compared with HI1N2,summer maize nitrogen uptake increased 18.93%,soil residual nitrogen decreased 4.94%,nitrogen loss by 26.58%.（5）Comprehensive analysis of nitrogen leaching losses,nitrogen utilization,summer maize yield and other indicators,under HI2N2 test scheme,the soil nitrogen accumulation effect is low,leaching loss minimum,ammonia volatilization loss less,nitrogen utilization efficiency is high,plant nitrogen transport in the scientific and efficient,to promote the field planting has a certain guiding significance.