Effects Of Controlled Release Urea Reduction On Soil Nitrogen Balance And Maize Yield

In response to the problem of excessive nitrogen fertilizer application and difficulty in synergistically improving yield and efficiency during the production of spring corn in the Yinbei Plain of Ningxia,this experiment used Lianchuang 825 as the test material and set up conventional urea application(UR:N 300 kg/hm2,base to top ratio 6:4),Under 20%nitrogen reduction,there are three treatments:50%conventional urea+50%controlled release urea(UR+CRU=1:1,N 240 kg/hm2,one-time basal application)and 100%controlled release urea(CRU:N 240 kg/hm2,one-time basal application),with no nitrogen application(CK)as the control.From the perspectives of corn yield,plant agronomic traits,dry matter and nitrogen accumulation and distribution,and soil nitrogen content,this study delves into the regulatory mechanism of reduced application of controlled release urea on the growth and development of spring corn and soil nitrogen balance,and explores a reasonable nitrogen fertilizer operation suitable for the synergistic improvement of spring corn yield and efficiency in the Yinbei Plain.This provides theoretical and technical support for the high yield and efficient cultivation of spring corn in this area.The main research findings are as follows:(1)Compared with conventional urea,reduced application of controlled release urea did not significantly reduce maize yield.Under three different treatment conditions,UR+CRU yield was the highest,followed by UR and CRU.Compared with UR,UR+CRU production increased by 0.50%,while CRU production decreased by 0.26%.Compared with CRU,UR+CRU production increased by 0.75%.(2)The reduction of controlled release urea did not significantly reduce the agronomic traits of maize.After setting the height of corn,compared with UR,the decrease in basal internode length of UR+CRU and CRU was 11.11%and 13.21%,respectively.CRU treatment had the strongest lodging resistance.Throughout the entire growth period,the leaf area index of maize is best at UR.The leaf area exponential growth increased rapidly in V12-R1 period,reached the maximum in R1 period,and gradually decreased after R1 period.At R1+25-R6,the leaf area index of UR+CRU and CRU treatments was close to that of UR.(3)Compared with conventional urea,reduced application of controlled release urea did not significantly reduce dry matter accumulation.During the entire growth cycle of the plant,UR was the best for total dry matter accumulation,followed by UR+CRU and CRU,but the proportion of dry matter after flowering showed CRU>UR+CRU>UR.Compared with UR,the total dry matter accumulation of UR+CRU and CRU decreased by 2.88%and 4.30%,respectively,but the proportion of dry matter after flowering increased by 4.46%and 7.53%,respectively.(4)Compared with conventional urea,reduced application of controlled release urea significantly improves nitrogen absorption and utilization in maize.During the R6 period,UR+CRU was the optimal nitrogen uptake in maize.Under different treatments,UR+CRU was the optimal treatment for total nitrogen accumulation,grain nitrogen content,nitrogen utilization efficiency,nitrogen fertilizer agronomic utilization efficiency,nitrogen fertilizer partial productivity,and nitrogen harvest index.(5)Compared with conventional urea,reduced application of controlled release urea significantly reduces nitrogen surplus.There were significant differences in soil nitrogen residue,apparent nitrogen loss,and soil nitrogen surplus with different nitrogen application rates.Compared with UR,UR+CRU and CRU have decreased soil residual nitrogen,nitrogen apparent loss,and soil nitrogen surplus by 14.42%,14.38%,14.40%,and 6.35%,15.73%,and 12.12%,respectively.In summary,it is recommended that the reasonable nitrogen fertilizer application method in the Yinbei Plain of Ningxia is to reduce the application amount by 20%,50%conventional urea+50%controlled release urea,and one-time basal application is the best.This fertilization method can not only improve corn yield,nitrogen utilization efficiency,and economic benefits,but also reduce nitrogen fertilizer loss.