氮素运筹对青贮玉米干物质积累及吸氮量的影响

Effects of Nitrogen Application on Dry Matter Accumulation and Nitrogen Absorption of Silage Corn

通过田间定位试验,系统研究了传统施氮、优化施氮等不同施肥模式对青贮玉米干物质积累、SPAD值、土壤硝态氮以及地上部氮素吸收规律的影响。结果表明:(1)将肥料全部基施(235 kg N/hm^(2))的传统施氮方式在青贮玉米六叶期前地上部干物质的累积量、SPAD值、0~30 cm土层土壤硝态氮含量显著高于优化施肥处理,但随时间的推移土壤硝态氮含量迅速降低,后期不能满足作物氮素需求导致青贮玉米地上部吸氮量及收获时干物质积累量均明显低于优化施肥处理;(2)调整施肥结构,将部分氮肥追施能够在减少氮肥投入25%~50%的基础上维持产量稳定,同时0~90 cm土壤硝态氮含量下降了35.36%~51.48%;(3)优化施氮量为156~180 kg/hm^(2)(基肥+追肥)时,比传统施氮模式平均增产3.37 t/hm^(2);(4)每生产1000 kg青贮玉米干物质,地上部吸氮量为7.78~10.15 kg。综上所述,采用优化施氮模式能够达到减肥增效的目的,即在保持青贮玉米高产、稳产的同时降低了氮素损失和环境风险,试验结果对指导青贮玉米实际生产具有重要的理论意义和实践价值。

A field experiment was conducted to compare traditional nitrogen application with optimized nitrogen application in terms of dry matter accumulation,soil plant analysis development(SPAD)value,soil nitrate nitrogen and aboveground nitrogen uptake in silage corn.The results showed:(1)Compared to the traditional method of applying all fertilizers as base(235 kg N/hm^(2)),the optimized nitrogen application significantly reduced the accumulation of dry matter in the aboveground part,SPAD value,and soil nitrate nitrogen content in the 0-30 cm soil layer before the 6th leaf stage of silage corn growth.Additionally,the nitrogen concentration in the aboveground part was significantly lower under the optimized nitrogen applica-tion than under the traditional fertilization approach.The soil nitrate nitrogen content in the traditional fertil-ization treatment decreased rapidly over time,failing to meet the nitrogen demand in the aboveground part during later growth stage.Consequently,nitrogen uptake and the accumulation of dry matter in the aboveg-round parts were significantly lower in the traditional fertilization treatment compared to the optimized treat-ment.(2)Adjusting the fertilization structure and applying part of the nitrogen as topdressing could main-tain a stable yield while reducing nitrogen input by 25%to 50%.Moreover,the residual nitrate nitrogen in the 0-90 cm soil layer decreased by 35.36%to 51.48%.(3)The optimal yield was achieved with a nitro-gen application of 156-180 kg/hm^(2)(basic fertilizer+topdressing),which increased the yield by 3.37 t/hm^(2)compared to the traditional fertilization treatment.(4)It was also observed that the production of 1000 kg silage corn resulted in an uptake of 7.78 to 10.15 kg of nitrogen in the aboveground parts.In conclusion,the optimized nitrogen application method can maintain the yield of silage corn while minimizing nitrogen loss and reducing environmental risks.These findings are significant for guiding the practical production of silage corn.