控释氮肥减量对作物产量、氮素吸收与径流损失的影响

Effects of controlled-release nitrogen fertilizer reduction on crop yield,nitrogen absorption and runoff loss

玉米蔬菜轮作是我国南方丘陵山地农区一种主要的旱地种植方式。为指导施肥,减少农业面源污染,于2020—2021年持续开展定位试验,探究控释氮肥及减氮处理对玉米小白菜轮作体系作物产量、氮素吸收残留、氮素径流损失的影响。试验共设置6个处理:CK,不施氮肥;U,常量施用普通尿素;CRU,施用等氮量的控释氮肥;90%CRU,施用控释氮肥,并较常量减氮10%;80%CRU,施用控释氮肥,并较常量减氮20%;70%CRU,施用控释氮肥,并较常量减氮30%。结果表明,与U处理相比,玉米在减氮20%条件下未显著减产,小白菜在减氮30%时均未显著减产。与U处理相比,合理施用控释氮肥可使总氮流失量显著(P<0.05)降低25.3%~43.5%,以70%CRU处理的总氮流失量最少。径流水中的氮素流失主要以颗粒氮为主,占比60.0%~67.0%。与U处理相比,除70%CRU处理外,其他施用控释氮肥处理的玉米地上部氮素积累量无显著差异;80%CRU处理的氮肥利用率显著提高9.4百分点。与U处理相比,施用控释氮肥0~80 cm各土层的总氮、铵态氮、硝态氮含量均未显著增加,不会提高土壤无机氮的流失风险。综上,在该试验条件下,与U处理相比,80%CRU处理可以在确保产量不降低的同时,减少氮素投入,降低氮素径流损失,提高肥料利用率,是试验条件下较为合理的施肥方式。

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 reduction on crop yield,N absorption,and N runoff loss in the maize-pakchoi rotation system.There were six treatments 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-release N fertilizer with the 90%N input amount as U treatment;80%CRU,application of controlled-release N fertilizer 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 significant 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-release 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 nitrogen in soil layers within 0-80 cm.In general,under the experiment conditions,80%CRU treatment could reduce N input and N runoff loss,enhance nitrogen use efficiency and ensure yield as compared with the U treatment,which exhibited reasonal application potential.