Effect Of Nitrogen Fertilizer Synergist Modified Coated Controlled-release Urea On Yield And Nitrogen Efficiency Of Summer Maize

At present,the nitrogen fertilizer use efficiency is low in Huang-Huai-Hai area,slow（controlled）release fertilizer and nitrogen fertilizer synergist can not achieve the expected effect in actual production,and the advantages of the two are complementary through the combination of nitrogen fertilizer synergist and controlled release fertilizer,the research and development of economical and environment-friendly slow-release and controlled-release nitrogen fertilizer is of great significance to the extension of green agriculture.The experiment was carried out in Wenliang Co-operative of Taian City from 2021 to 2022.Denghai 605（DH605）was selected as the experimental material,and the seeds were sown in mid-to-early June.Coated urea with different controlled release periods（30 d and 60 d）was used,different nitrogen application rates(0,168 kg N ha^-1,210 kg N ha^-1)and inhibitor treatments(adding nitrification inhibitor-dicyandiamide（DCD,T1）,adding urease inhibitor-n-butyl thiophosphoryltriamine（NBPT,T2）,adding DCD and NBPT（DCD+NBPT,T3）,and no adding treatment（T4）were applied.In order to provide some technical support for the green development of agriculture,the effect of coated controlled-release urea（CRU）on the yield formation,nitrogen utilization and environmental benefit of summer maize was studied by using the combination of coating and inhibitor to prepare different formula nitrogen fertilizer synergist.The results were as follows:1.Effect of coated controlled-release urea modified by nitrogen fertilizer synergist on yield and economic benefit of summer maizeThe grain number per ear,1000-grain weight and yield of summer maize were significantly increased by using nitrogen fertilizer synergist and coated controlled-release urea,among which the treatment of T3 was the best,and the yield was increased by 9.88%on average compared with the treatment of T4 coated controlled-release urea.Under the same controlled release period,the yield of summer maize treated with coated controlled release urea T3 was higher than that treated with coated controlled release urea T4 under the condition of 20%nitrogen reduction,and reached the effect of T1 and T2 treatments.Under the same nitrogen application rate,the yield of summer maize treated with coated urea T3 for 30 days reached that of coated urea T4 for 60 days.The yield of summer maize treated with coated controlled-release urea（30d）T3（K30-11.2-T3）was 6.14%higher than that treated with coated controlled-release urea（30d）T4（K30-14-T4）under the condition of 20%nitrogen reduction.The yield of summer maize treated with coated controlled-release urea（60 d）T3（K60-11.2-T3）was 8.6%higher than that treated with coated controlled-release urea（60 d）T4（K60-14-T4）under the condition of 20%nitrogen reduction.The yield of summer maize treated with coated urea T3（K30-14-T3）for 30d was 8.61%higher than that treated with coated urea T4（K60-14-T4）for 60 days The yield of summer maize treated with coated urea T3（K30-11.2-T3）for 30 d was 5.64%higher than that treated with coated urea T4（K60-11.2-T4）for 60 days.The yield of coated urea T3（K30-11.2-T3）at 30 d of controlled release period was not significantly different from that of coated urea T4（K60-14-T4）at 60 d of controlled release period under 20%nitrogen application.Nitrogen fertilizer synergist improved coated controlled-release urea increased the input cost of fertilizer but also increased the total benefit.The total return of K30-14-T3 was 10.23%higher than that of K30-14-T4.The total return of K30-11.2-T3 was 12.23%higher than that of K30-11.2-T4.The total return of K60-14-T3 was 19.28%higher than that of K60-14-T4.The total return of K60-11.2-T3 was 11.95%higher than that of K60-11.2-T4.K30-14-T3 increased by 10.43%compared with K60-14-T4,and K30-11.2-T3 increased by 4.14%compared with K60-11.2-T4.It was concluded that T3 increased the yield and benefit of coated controlled-release urea under the condition of 20%nitrogen reduction,but the cost of nitrogen fertilizer was lower,the benefit was better and the application was easier.2.Effect of coated controlled-release urea modified by nitrogen fertilizer synergist on dry matter accumulation and distribution in summer maizeThe leaf area index（LAI）and leaf area index（SPAD）of summer maize were increased by using coated controlled-release urea（CRU）modified by nitrogen fertilizer synergist,the LAI and SPAD of T3 treatment were increased by 7.95%and 5.53%compared with T4treatment at VT stage,while the leaf area index and SPAD of summer maize were decreased at R3 and R6 stage,the decrease of LAI and SPAD was reduced by coated controlled-release urea and nitrogen fertilizer synergist,which ensured the photosynthetic performance and assimilate accumulation after anthesis.All treatments of coated controlled-release urea improved by nitrogen fertilizer synergist significantly increased the dry matter accumulation of summer maize at different growth stages,especially after anthesis,and increased grain dry matter accumulation at mature stage,the distribution of dry matter to grain was increased significantly,and the increase of T3 treatment was the most significant.The dry matter accumulation,grain dry matter accumulation and distribution of T3 at maturity stage increased by 19.31%,18.78%and 3.41%compared with T4 treatment.3.Effect of nitrogen fertilizer synergist on soil inorganic nitrogen by modified coated controlled-release ureaApplication of coated controlled-release urea with nitrification inhibitor and urease inhibitor increased 0-20 cm ammonium nitrogen content in jointing stage and flowering stage,and significantly decreased 20-60 cm nitrate nitrogen content in soil layer,the risk of leaching caused by high concentration of nitrate nitrogen in earlier stage was reduced.After anthesis,the nitrate content in 0-20 cm soil layer decreased slightly but not significantly compared with the unimproved soil layer,and maintained at a certain level,the nitrate-N content in the soil surface layer was guaranteed during the later growth stage of summer maize,which was more favorable to plant nitrogen uptake.4.Effects of coated controlled-release urea modified by nitrogen fertilizer synergist on soil greenhouse gas and ammonia volatilizationModified coated controlled-release urea with nitrogen fertilizer synergist significantly reduced GWP and GHGI.Compared with K30-14-T4,K30-14-T1,K30-14-T2,K30-14-T3 and K60-14-T4 decreased GWP by 16.22%,10.97%,21.96%,25.99%,and GHGI by 19.68%,15.43%,28.72%,26.59%,respectively.Combined with the analysis of GWP and GHGI,K30-14-T3 had the most significant emission reduction effect.Compared with T4 treatment,T1 treatment increased ammonia volatilization flux,and T2and T3 treatment significantly reduced ammonia volatilization flux.The cumulative ammonia volatilization flux of K30-14-T1 was 15.90%higher than that of K30-14-T4 treatment,and the cumulative ammonia volatilization flux of K30-14-T2 and K30-14-T3 was 18.24%and 8.87%lower than that of K30-14-T4 treatment,respectively,there was no significant difference between K30-14-T3 and K60-14-T4.5.Effect of coated controlled-release urea modified by nitrogen fertilizer synergist on nitrogen efficiency of summer maizeThe coated controlled-release urea with nitrogen fertilizer synergist improved the nitrogen accumulation and nitrogen efficiency of summer maize at all stages,and the treatment of T3had the best effect.The NUE of K30-14-T3 was 17.67%higher than that of K30-14-T4.The NUE of K30-11.2-T3 was 21.76%higher than that of K30-11.2-T4.The NUE of K60-14-T3was 12.82%higher than that of K60-14-T4 The NUE of K60-11.2-T3 was 11.05%higher than that of K60-11.2-T4.The NUE of K30-11.2-T3,K60-11.2-T3 were significantly higher than that of K60-14-T4.In conclusion,the co-application of coated controlled-release urea with DCD and NBPT increased the NH₄⁺-N content of 0-20 cm soil surface layer at jointing stage and flowering stage,decreased the NO₃^--N content and reduced the nitrate leaching risk,it inhibited nitrification and Denitrification,significantly increased nitrogen efficiency,increased the accumulation,transport and distribution of assimilates to grains after anthesis,improved yield components,reduced GWP and GHGI,and increased the yield of maize,increased economic efficiency.Under the condition of reducing nitrogen by 20%,the co-application of coated controlled-release urea with DCD and NBPT can reduce the cost of fertilizer and guarantee the yield,increase the net income,and reduce the emission of greenhouse gas and ammonia volatilization,more conducive to agricultural extension.