Effects Of Irrigation Amount,Nitrogen Fertilizer Types And Amount On Summer Maize/Winter Wheat Yield,Water And Nitrogen Utilization

At present,the phenomenon of excessive irrigation and nitrogen application in farmland is widespread,which results in low resource utilization efficiency and increased risk of environmental pollution.It has become one of the key issues restricting the sustainable development of agriculture in China.Slow/controlled release nitrogen fertilizer can control the rate of nutrient release or prolong the nitrogen conversion process.One-time basal application can continuously supply the demand of crops which reduces labor input while increasing production and saving fertilizer.However,the effect of slow/controlled release nitrogen fertilizers is closely related to the types of fertilizers,water and nutrient supply and other factors,which need to be further resolved.In this study,summer maize Zhengdan 958 and winter wheat Xinong 979 were taken as the research objects,and the split-split zone experiment was conducted with irrigation amount as the main treatment,nitrogen rates as the secondary treatment,and nitrogen fertilizer types as the vice secondary treatment?Irrigation amount was set at three levels:low water W1?30mm?,medium water W2?60 mm?and high water W3?90 mm?.Summer maize and winter wheat were irrigated once.The application of nitrogen fertilizer was set at three levels:low nitrogen N1,medium nitrogen N2 and high nitrogen N3;The amount of nitrogen applied in the maize season was 90 kg·hm^-2,180 kg·hm^-2 and 270 kg·hm^-2,respectively,and the wheat season was 75 kg·hm^-2,150 kg·hm^-2 and 225 kg·hm^-2.There were 4 types of nitrogen fertilizer:?1?common urea?CO?as a control;?2?Resin-coated urea?PCU?;?3?Sulfur plus resin-coated urea?SPCU?;?4?Urea+nitrification inhibitor?DMPP?.In addition,set a non-nitrogen treatment at each of the three water levels,so there were 39 treatments in this experiment.To study the influence of single factors of nitrogen fertilizer type,nitrogen application rate and irrigation amount and their interaction on the yield,water and nitrogen utilization of summer maize and winter wheat,and using the yield,water use efficiency,nitrogen use efficiency and the NO₃^--N residual amount as indicators,using gray correlation method,membership function analysis method,TOPSIS method and principal component analysis method to establish a single evaluation model,on this basis,fuzzy Borad combination evaluation method to establish a combined evaluation model,put forward the comprehensive optimal nitrogen fertilizer type and the application of summer maize/winter wheat yield and water and nitrogen utilization in the Guanzhong Plain,provide guidance for high-yield and efficient agricultural production.The main results are as follows:?1?Analysis of variance showed that irrigation,irrigation amount,nitrogen rates,and nitrogen fertilizer types all had significant effects on summer maize and winter wheat yields;the interaction between irrigation and nitrogen fertilizer types had a significant effect on crop yield,and the interaction of the three factors had no significant effect on crop yield.The crop yield was the highest when the irrigation and nitrogen application were at the middle level.The yield of crops treated with slow-release nitrogen fertilizer was higher than the CO treatment,and the yield of DMPP treatment is the highest,which compared with CO treatment,maize and wheat yields increased by 5.3%and 8.2%,respectively.According to binary quadratic regression model of yield,irrigation and nitrogen application,it is recommended that summer maize be treated with urea+DMPP.The maize yield can reach 8945 kg·hm^-2 when the irrigation and nitrogen rate are 61 mm and 223 kg·hm^-2,respectively.Winter wheat season is treated with urea+DMPP,and the wheat yield can reach 7584 kg·hm^-2 when the irrigation and nitrogen rate are 71 mm and 170 kg·hm^-2,respectively.?2?Irrigation amount,nitrogen rates,and nitrogen fertilizer types all had a very significant effect on the water use efficiency?WUE?of summer maize and winter wheat.The interaction of irrigation amount and nitrogen fertilizer type had a significant effect on WUE of winter wheat,the interaction of two factors and three factors had no significant effect on WUE of summer maize,and the interaction of three factors had no significant effect on WUE of winter wheat.With the increase of irrigation amount,summer maize WUE showed a trend of increasing first and then decreasing;while winter wheat WUE gradually decreased.When the nitrogen application rate was N2,the WUE of maize and wheat reached the maximum.The WUE of crops treated with slow-release nitrogen fertilizer were higher than the CO treatment,and the highest in DMPP treatment,which compared with CO treatment,maize and wheat increased by 11.3%and 13.3%,respectively.According to the binary quadratic regression model of WUE,irrigation and nitrogen application,it is recommended that in summer maize season is treated with urea+DMPP,and WUE can reach 2.46 kg·m^-3 when the irrigation and nitrogen rate are 51 mm and 173kg·hm^-2,respectively.In winter wheat season,WUE is up to 2.04 kg·m^-3 with the application of urea+DMPP,irrigation and nitrogen rate of 31 mm and 151 kg·hm^-2.?3?Irrigation amount had no significant effect on the nitrogen use efficiency?NUE?of summer maize,and it had a significant effect in winter wheat?NUE?.Both nitrogen rates and nitrogen fertilizer types had a very significant effect on summer maize and winter wheat NUE;the interaction of two factors and three factors had no significant effect on maize and wheat NUE.Within a certain range,the NUE of crops increased first and then decreases with the increase of irrigation amount;it decreased with the increase of nitrogen application rate.The NUE of crops treated with slow-release nitrogen fertilizer was higher than that with common urea treatment.Among them,the NUE of DMPP treatment was the largest,which increased by 9.9%and 14.2%respectively compared with CO treatment of summer maize and winter wheat.Considering the effects of irrigation and nitrogen application rate on nitrogen utilization efficiency,it is recommended to use PCU in summer maize season,NUE can reach 38.50 kg·kg^-1when the irrigation and nitrogen rate are 55mm and 90 kg·hm^-2,respectively.Winter wheat season is treated with urea+DMPP,the irrigation and nitrogen rate are 63 mm and 92 kg·hm^-2,respectively;and the NUE can reach 46.19 kg·kg^-1.?4?Irrigation,nitrogen rates,and nitrogen fertilizer types all had a very significant effect on the NO₃^--N residual amount in 0-160 cm soil of summer maize and winter wheat harvest.The interaction between irrigation and nitrogen rates,nitrogen rates and nitrogen fertilizer type had a very significant effect on the NO₃^--N residual amount in maize and wheat.The interaction between irrigation and nitrogen fertilizer type had no significant effect on the residual amount of nitrate nitrogen in summer maize,but the effect on winter wheat was significant;The interaction of the three factors had no significant effect on the NO₃^--N residual amount.The NO₃^--N residual amount was positively correlated with the amount of nitrogen applied in irrigation.The residual NO₃^--N amount of crops treated with slow-release nitrogen fertilizer was lower than the CO treatment.The value of residual NO₃^--N in DMPP treatment was the smallest,which was 40.5%and 62.2%less than that in CO treatment of summer mazie and winter wheat,respectively.It is recommended to use urea DMPP treatment,irrigation amount is 30 mm,summer maize nitrogen rate is 90kg·hm^-2,winter wheat nitrogen rate is 75 kg·hm^-2,then the residual NO₃^--N amount is less than 80 kg·hm^-2.?5?The results of a single evaluation method show that,when comprehensively considering crop yield,water and nitrogen use,and soil nitrate nitrogen residue,irrigation and nitrogen rates were ranked first at the middle level,and slow-release nitrogen fertilizer treatment was ranked higher than urea treatment,with DMPP treatment being the highest.The fuzzy Borda combination evaluation showed that the optimal water and fertilizer programs for summer maize and winter wheat were DMPP treatments with middle water and nitrogen application.The worst program for summer maize was ordinary urea treatment with high water and nitrogen application,and the worst program for winter wheat was CO treatment with irrigation W1 and nitrogen application N3.Based on the fuzzy Borda combination evaluation model,the best nitrogen fertilizer type for summer maize season is urea+DMPP,and the recommended water and nitrogen rate are 52-62 mm and146-203 kg·hm^-2,respectively.The available mazie yield is 8751-8922 kg·hm^-2,WUE is2.43-2.45 kg·m^-3,NUE is 37.65-38.16 kg·kg^-1,and the NO₃^--N residual amount is 90-114 recommended water and nitrogen rate are 55-68 mm and 136-168 kg·hm^-2,respectively.The available winter wheat yield is 7362-7579 kg·hm^-2,WUE is 2.07-2.08 kg·m^-3,NUE is44.34-44.94 kg·kg^-1,and the NO₃^--N residual amount is 66-80 kg·hm^-2.