Effects of controlled-release nitrogen fertilizer reduction on crop yield,nitrogen absorption and runoff loss
Maize-vegetable rotation is one of the main dryland cultivation methods in hilly and mountainous farming areas in southern China.In order to guide the rational fertilization,reduce agricultural non-point source pollution,a field experiment was conducted in 2020-2021 to explore the effects of controlled-release nitrogen(N)fertilizer re-duction on crop yield,N absorption,and N runoff loss in the maize-pakchoi rotation system.There were six treat-ments in this experiment:CK,No N fertilizer supplied;U,conventional fertilization with urea;CRU,application of controlled-release N fertilizer with the same N input amount as U treatment;90％CRU,application of controlled-re-lease N fertilizer with the 90％N input amount as U treatment;80％CRU,application of controlled-release N fertil-izer with the 80％N input amount as U treatment;70％CRU,application of controlled-release N fertilizer with the 70％N input amount as U treatment.The results showed that compared with the U treatment,there was no signifi-cant reduction in maize yield or cabbage yield with 20％or 30％N reduction,respectively.Compared with the U treatment,application of appropriate amount of controlled release nitrogen could significantly(P＜0.05)reduce the total nitrogen loss by 25.3％-43.5％,and the the total nitrogen loss was the least under 70％CRU treatment.The main nitrogen loss in runoff water was particle nitrogen,which accounted for 60.0％-67.0％.Compared with the U treatment,there was no significant decrease in the nitrogen accumulation in shoot with application of controlled-re-lease nitrogen fertilizer except the 70％CRU treatment,yet 80％CRU treatment significantly increased the nitrogen use efficiency by 9.4 percentage points.Compared with the U treatment,application of f controlled-release nitrogen fertilizer did not significantly increse the contents or the loss risk of total nitrogen,ammonium nitrogen and nitrate ni-trogen in soil layers within 0-80 cm.In general,under the experiment conditions,80％CRU treatment could re-duce N input and N runoff loss,enhance nitrogen use efficiency and ensure yield as compared with the U treatment,which exhibited reasonal application potential.
controlled-release nitrogen fertilizeryieldrunoff lossnitrogen use efficiencysoil nitrogen
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