控释尿素一次性施用的玉米减氮增效研究

基于田间小区试验，在常规施氮（U100，普通尿素，施氮量250 kg/hm²）基础上，设置普通尿素、控释尿素减量20%（U80和C80）和40%处理（U60和C60），通过测定玉米产量及产量构成、氮素吸收和利用效率，结合土壤养分动态和植株光合特征与氮同化关键酶活性，评价控释尿素在玉米减氮增效中的作用。结果表明，氮肥减量20%时玉米产量和氮肥利用率都达到常规施氮水平，其中C80比U80增产14.5%；氮肥减量40%后产量有所降低，减产原因主要是百粒质量降低7.0%~9.5%。与U100相比，减氮20%的光合特征，土壤硝铵态氮水平，谷氨酸脱氢酶（NADH-GDH）、谷草转氨酶（GOT）和谷氨酰胺合成酶（GS）的活性均未显著下降，其中C80的净光合速率和光合氮利用效率比U100显著提高15.0%和24.8%，且C80较U80在提高氮素吸收总量、氮利用率、收获指数、光合氮利用率、酶活性和维持籽粒百粒质量方面更具优势。减氮40%后，U60的酶活性和光合特征与U100相比平均降低31.5%和27.6%，而C60的光合氮利用效率达到常规施氮水平。可见，氮肥减量20%时可以有效维持玉米产量，其中控释尿素一次性施用效果更佳，值得推广应用。

Study on Reducing N Fertilizer and Increasing Nutrient Use Efficiency of Maize With One-time Application of Controlled-release Urea

Reduced nitrogen(N) application rate is an important approach to realize the sustainable development of agriculture in China.Conventional N application(U100,common urea at a rate of 250 kg/hm²),common urea and controlled-release urea application with a N reduction of 20%(U80 and C80) and 40%( U60 and C60) were conducted respectively through a field plot experiment.Maize yield,yield components,N uptake and N use efficiency(NUE) were detected; soil nutrient dynamics,photosynthetic characteristics and key enzyme activites for N assimilation were analyzed,and the role of controlled-release urea in reducing N fertilizer application and increasing NUE was evaluated.The results showed that both the maize yield and NUE were equal to the treatment of U100 although reduced 20% N application rate,and the maize yield increased by 14.5% in C80 compared to U80.The maize yield decreased because the 100-grain mass was reduced by 7.0%-9.5% ,after 40% N was reduced.Compared with U100,reduced 20% N fertilizer did not result in lower photosynthetic characteristics,soil nitrate N,ammonium N ,NADH-GDH,GOT and GS activities.In addition,the net photosynthetic rate and photosynthetic NUE increased by 15.0% and 24.8% respectively under the treatment of C80 compared to U100.Compared to U80,C80 presented more advantages in improving total N uptake,NUE,harvest index,photosynthetic NUE,N assimilation enzyme activity,and maintaining 100-grain mass.N assimilation enzyme activity and photosynthetic characteristics reduced by 31.5% and 27.6%,respectively under the treatment of U60 compared to U100,while the photosynthetic NUE of C60 still reached the same level under treatment of U100.It is concluded that maize yield can be maintained when N fertilizer is reduced by 20%,and one-time application of controlled release urea is more effective,which is worth being widely applied.