Study On Variation Mechanism Of Maize And Rice Yield And Nitrogen Use Efficiency In Northeast China

As important food and feed crops in China,Rice and corn are of great significance to the food security of our country.In order to improve the yield of rice and corn in Northeast China,this study based on the field experiment data of rice and corn "3414" since 2010 in Northeast China,studied the differences of different recommended fertilization models under different soil types and different fertility levels of the same soil types,and provided theoretical basis for the selection of recommended fertilization models in different soil types and different fertility levels of the same soil types in Northeast China;To study the variation mechanism of fertilizer utilization rate of rice and corn,to find out the main factors affecting fertilizer utilization rate,and to establish the variation mechanism model of fertilizer utilization rate,to provide theoretical basis for improving fertilizer utilization rate,reducing waste of fertilizer resources and solving the problem of environmental pollution caused by excessive fertilization.The main findings are as follows:(1)The research results of recommended fertilization model for maize in Northeast China show that the fitting degree,recommended amount,target yield and fertilizer utilization efficiency should be taken into account in the selection of fertilization model.The four fertilizer effect function models have different fitting effects under different soil types and fertility levels.Taking into account the fitting degree of fertilizer effect function,recommended fertilization amount,and target yield,on low fertility white pulp soil and meadow soil,the fitting effect was as follows: linear plus platform model > ball model > quadratic term model > index model,using linear plus platform model compared ball model,quadratic term model and index model to save 60-93,73-95 and 84-114 kg/hm2 nitrogen fertilizer,respectively.The fitting results are as follows: linear plus platform model > ball model > index model > quadratic term model,using linear plus platform model to save 68-73,84-87 and 89-91 kg/hm2 nitrogen fertilizer,respectively.On medium fertility dark brown soil,black calcareous soil,black soil and sandy soil,the fitting effect is as follows: linear platform model > sphere model > quadratic term model > index model,using linear platform model to save 72-93,75-103 and 89-113 kg/hm2 nitrogen fertilizer 75-103 and 89-113 kg/hm2 nitrogen fertilizer,respectively.Compared with spherical model,quadratic model and exponential model,the quadratic model saves 78-100,97-103 and 85-126 kg/hm2 nitrogen fertilizer respectively.The fitting effect is as follows: linear platform model > quadratic term model > ball model > index model,using linear platform model to save 105-118,121-134 and 165-168 kg/hm2 nitrogen fertilizer on higher fertility clay.Compared with spherical model,quadratic term model and exponential model,the linear plus platform model was used to save 154,154 and 155 kg/hm2 nitrogen fertilizer,respectively.(2)According to the results,soil,crop and fertilizer are the three main factors in the variation of nitrogen fertilizer utilization efficiency of rice and maize in Northeast China.974.This model is used to predict the efficiency of nitrogen fertilizer agronomy in maize and rice.The linear fitting red line between the predicted value and the measured value coincides with the black dotted line in the y=x diagram,indicating that the measured value is basically equal to the predicted value of the model,indicating that the model based on these three main factors can accurately predict the agricultural utilization efficiency of nitrogen fertilizer;CNSD and NRSC are two ways to change the efficiency of maize and rice nitrogen fertilizer agronomy in northeast china.CNSD can link crops well with soil,but NRSC can link fertilizer well with soil.These two ways provide a theoretical basis for improving the efficiency of maize and rice nitrogen fertilizer agronomy in northeast china.(3)The simulation of rice and maize yield in Northeast China shows that: the CNSD and NRSC are used to establish the prediction models of maize and rice yield in Northeast China,which are 0.968 and 0.925 respectively.And through the model to predict the maize and rice yield in Northeast China,the predicted yield and the measured yield are linearly fitted.The results show that the fitting red straight line coincides with the y=x line,which indicates that the established model is of practical significance and can predict the maize and rice yield well in Northeast China.