Effects Of Nitrogen Application On Yield And Nitrogen Utilization Of Spring Maize In Dry-land

Reasonable nitrogen application rate and fertilization method are effective ways to increase maize yield.On the basis of nitrogen gradient experiment,a split design was applied for the experiment to study the effects of three application methods on dry-land spring maize yield,economic income,dry matter accumulation,nitrogen accumulation and utilization,and soil inorganic nitrogen residues under different nitrogen application rates.This study providing theoretical support for high-yield and high-efficiency fertilization of spring maize.The main factor included three application methods,solid granular urea one-time fertilization（OF）,solid granular urea top-dress fertilization（TF）,and one-time application of a mixture of controlled-release urea and solid granular urea（MF）,and the sub-factors included six different nitrogen application rates of 0,60,120,180,240,300 kg/hm²（N0,N60,N120,N180,N240,N300）.The main results were as follows:（1）The results of nitrogen gradient experiment showed the liner-plateau model had the best fit for the maize yield response curves to nitrogen rate.At the three experiment sites in Zhuanglang,Pengyang,and Yingxian,the yields were not increased until nitrogen application rate beyond 60,120,120 kg/hm²（2019）and 120,120,240 kg/hm²（2020）,and at this time,the corresponding yields were 11.3,8.9,11.9 t/hm²（2019）and 13.2,10.1,13.9t/hm²（2020）,respectively.The yields of spring maize were no difference in different nitrogen application rate in Changwu.（2）The yield,economic income and the dry matter accumulation were increased significantly with the nitrogen application rate increased.When the nitrogen application rate reached a certain value,the yield,economic income and the dry matter accumulation were no longer increased significantly.Among the three nitrogen fertilizer application methods,the MF increased the yield,economic income,and dry matter accumulation of pre-silking and post-silking,significantly.（3）The LAI and SPAD values of spring maize were increased significantly with the increase of nitrogen application rate.When the nitrogen application rate was 240 kg/hm²,the LAI and SPAD values were the largest.Compared with OF,the MF increased the LAI and the SPAD values,significantly.（4）The pre-silking nitrogen accumulation,post-silking nitrogen accumulation,total nitrogen accumulation and amount of stem nitrogen transfer and leaf nitrogen transfer were increased significantly with the increase of nitrogen application rate.Among the three nitrogen fertilizer application methods,these indicators were significantly the highest with the MF.（5）With the increase of nitrogen application rate,the NAE and PFP were decreased significantly,and the N_min at harvest and apparent loss of soil inorganic nitrogen increased significantly.Compared with OF,the NAE and PFP were increased significantly,and the N_min at harvest and apparent loss of soil inorganic nitrogen were decreased significantly with the MF.