Regulation Of Long-term Location Reduction Of Controlled-release Nitrogen Fertilizer On Annual Nitrogen Utilization And Yield Of Wheat And Maize

The experiment began in the winter wheat growing season from 2020 to 2021 and was carried out in the field of National key wheat demonstration base,Daolang Town,Tai’an City,Shandong Province.The tested wheat variety was‘Shannong 29’and maize variety‘Denghai 618’.The experiment was conducted on high fertility silty soil.The fertilizer was controlled-release mixed fertilizer,and the controlled-release N:available N was 7:3.The controlled-release fertilizer was resin coated controlled-release urea provided by Shandong Agricultural University fertilizer industry,and the release cycle was about 60 days.The positioning test began in 2015,The six-year positioning test and one-year short-term test were used as controls.Ten treatments were set up in the winter wheat season experiment.The ten treatments in the positioning experiment were:no nitrogen,phosphorus and potassium（E1N0）;120kg hm^-2 of phosphorus and potassium,240 kg hm^-2 of nitrogen（E1N1）;192 kg hm^-2 of nitrogen（E1N2）;144 kg hm^-2 of nitrogen（E1N3）;96 kg hm^-2of nitrogen（E1N4）;48 kg hm^-2 of nitrogen（E1N5）;no nitrogen（E1N6）;The amount of nitrogen application is 192 kg hm^-2,the amount of potassium is 96 kg hm^-2,the amount of phosphorus is 120 kg hm^-2（E1N7）;the amount of nitrogen application is 192 kg hm^-2,the amount of potassium is 96 kg hm^-2,the amount of phosphorus is 96 kg hm^-2（E1N8）;the amount of nitrogen application is 240kg hm^-2,the amount of phosphorus and potassium is 120 kg hm^-2,of which 120 kg hm^-2 is applied at sowing stage and 120 kg hm^-2（E1N9）is applied at jointing stage.Among them,the corresponding one-year short-term tests are W1N0,W1N1,W1N2,W1N3,W1N4,W1N5,W1N6,W1N7,W1N8 and W1N9 respectively.Ten treatments were set up in the summer maize season experiment,and the ten treatments in the positioning experiment were as follows:1 No nitrogen,phosphorus and potassium application（E2N0）;120 kg hm^-2 of phosphorus and potassium,336 kg hm^-2 of nitrogen（E2N1）;270 kg hm^-2of nitrogen（E2N2）;203 kg hm^-2 of nitrogen（E2N3）;135 kg hm^-2 of nitrogen（E2N4）;68 kg hm^-2 of nitrogen（E2N5）;no nitrogen（E2N6）;270 kg hm^-2 of nitrogen,96 kg hm^-2 of potassium,120 kg hm^-2 of phosphorus（E2N7）;270 kg hm^-2 of nitrogen,Potassium is 96 kg hm^-2,phosphorus is 96 kg hm^-2（E2N8）;common chemical fertilizer is 336 kg hm^-2,phosphorus and potassium is 120kg hm^-2,in which nitrogen is 168 kg hm^-2 at sowing stage and 168 kg hm^-2 at large bell mouth stage（E2N9）.Among them,the corresponding one-year short-term tests are W2N0,W2N1,W2N2,W2N3,W2N4,W2N5,W2N6,W2N7,W2N8 and W2N9 respectively.1 Effects of long-term location reduction of controlled-release nitrogen fertilizer on grain yield of winter wheat-summer maizeWinter wheat season:in the long-term positioning experiment,the grain yield of controlled-release fertilizer(144 kg hm^-2)decreased by 1.62%compared with contr olled-release fertilizer(240 kg hm^-2),and decreased by 0.47%compared with the phased application of general chemical fertilizer(240 kg hm^-2).The results showed that the controlled-release fertilizer(144 kg hm^-2)could still maintain a high yield in the long-term positioning test.In the short-term experiment,the application of ordinary chemical fertilizer(240 kg hm^-2)by stages was better than the application of controlled-release fertilizer(240 kg hm^-2)at the bottom.Compared with W1N1,the panicle number of W1N3 decreased,the 1000 grain weight increased,and there was no significant difference in yield.The results showed that the controlled-release fertilizer(144 kg hm^-2)could still maintain a high yield in the short-term experiment.Summer maize season:in the long-term positioning test,the treatment with the maximum yield and grain number per ear was E2N2 and the treatment with the minimum 1000 grain weight was E2N1.The results showed that fertilization of more than 270 kg hm^-2 in maize season would lead to the decrease of grain number per ear,1000 grain weight and yield.Compared with E2N7 and E2N8,E2N2 increased by 4.4%and 6.01%,indicating that phosphorus and potassium reduction on the basis of nitrogen reduction by 20%of controlled-release fertilizer in long-term positioning test will reduce the yield of summer maize.In the long-term experiment,the grain yield of controlled-release fertilizer(135 kg hm^-2)decreased by 1.67%compared with that of controlled-release fertilizer(270 kg hm^-2).In the short-term experiment,the grain yield of controlled-release fertilizer(203 kg hm^-2)decreased by 4.39%compared with that of controlled-release fertilizer(270 kg hm^-2).The yield can still maintain a high level when the nitrogen application rate is 135 kg hm^-2in the long-term positioning experiment.In the short-term experiment,the nitrogen application rate of 203 kg hm^-2can still maintain a high yield.2 Effects of long-term targeted reduction of controlled-release nitrogen fertilizer on dry matter accumulation of winter wheat-summer maizeWinter wheat season:in the long-term positioning experiment,the dry matter accumulation of 40%(144 kg hm^-2)nitrogen reduction by controlled-release fertilizer can still maintain a high level.The short-term test is consistent with the long-term positioning test.Summer maize season:in the long-term and short-term experiment,the dry matter accumulation of summer maize reached the maximum when controlled-release fertilizer reduced nitrogen by 20%(270 kg hm^-2).Excessive nitrogen application will reduce the dry matter accumulation.In the long-term positioning experiment,the nitrogen application rate of controlled-release fertilizer 203 kg hm^-2can still maintain a high dry matter accumulation of summer maize.In the short-term experiment,the application of controlled-release fertilizer and nitrogen application rate of 270 kg hm^-2can maintain a high dry matter accumulation of summer maize.3 Effects of long-term location reduction of controlled-release nitrogen fertilizer on nitrogen accumulation of winter wheat-summer maizeWinter wheat season:in the long-term positioning experiment,under the condition of controlled-release fertilizer reducing nitrogen by 40%(144 kg hm^-2),winter wheat still has high nitrogen accumulation.In the short-term experiment,under the condition of controlled-release fertilizer reducing nitrogen by 20%(192 kg hm^-2),winter wheat still had high nitrogen accumulation.Summer maize season:in the long-term and short-term experiments,the nitrogen accumulation of summer maize was the highest under the condition of controlled-release fertilizer reducing nitrogen by 20%(270 kg hm^-2).Excessive fertilization led to the decline of nitrogen accumulation.In the long-term experiment,the treatment with nitrogen application rate of 135 kg hm^-2 could still maintain a high nitrogen accumulation.In the short-term experiment,when the nitrogen application rate of controlled-release fertilizer was 203 kg hm^-2,it could still maintain a high nitrogen accumulation.To sum up,this study believes that the nitrogen application rate under the winter wheat summer maize rotation system is affected by the rotation years.If the years are short,the nitrogen application rate in winter wheat season can be 144 kg hm^-2,and that in summer maize season can be 203 kg hm^-2.If the years are long,the nitrogen application rate in summer maize season can be reduced to 135 kg hm^-2,and the nitrogen application rate in winter wheat season remains unchanged.