春甘蓝-玉米-冬甘蓝轮作制下氮肥施用量研究

Study on the Effect of Different Nitrogen Rates in Spring Cabbage-Maize-Winter Cabbage Rotation System

【目的】探讨土壤无机氮含量对春甘蓝-玉米-冬甘蓝轮作甘蓝获得最高产量的施氮量和氮肥利用率的影响及施用氮肥与甘蓝产量和品质的关系,为该轮作制高产优质安全的氮肥施用技术提供依据。【方法】采用田间定位试验研究0、90、180、270、360、450kg·ha-16个施氮水平在两种无机氮含量土壤上春甘蓝、玉米、冬甘蓝产量、氮肥利用率及甘蓝水溶性糖、Vc、硝酸盐含量的变化。【结果】供试土壤无机氮含量显著影响第一季春甘蓝获得最高产量的施氮量,土壤无机氮含量高,春甘蓝最大施氮量降低,土壤无机氮含量对后茬冬甘蓝影响减弱,表明土壤无机氮变化活跃,只对当季作物施肥具有指导意义。当地习惯施氮量高出甘蓝获得最大产量施氮量的1.8～3.2倍,已引起地下水NO3--N的富积。施氮量和土壤剖面中无机氮含量均影响甘蓝氮肥利用率,甘蓝套玉米有利于高氮处理的氮肥利用率的提高。氮肥用量低时(用量在90kg·ha-1以内时),可同时提高甘蓝的产量和品质;氮肥用量进一步提高时,甘蓝产量还可进一步提高,但品质下降;当氮肥用量过高时,则甘蓝产量品质均下降。因而在生产上要获得优质蔬菜产品,需要减少氮肥用量降低产量来获得。【结论】土壤无机氮含量与当季甘蓝获得最高产量的氮肥用量和氮肥利用率密切相关。砂姜黑土氮肥后效明显,甘蓝与玉米轮作能提高高氮处理氮肥利用率。氮肥用量影响甘蓝产量和品质,要获得较好品质的蔬菜,必须减少氮肥用量降低产量来获得。

[ Objective] The effects of inorganic N content in soil on the N rate for obtaining maximum yield, N utilization rate and the relation of cabbage yield and quality with N rate in spring cabbage-corn-winter cabbage rotation system were conducted, [Method] Field location experiments were carried out to study the changes of crop yield, N utilization rate, water-soluble sugar content, Vc content and nitrate content in different inorganic-N content soils after application of 0, 90, 180, 270, 360, 450 kg.ha^-1 N, [Result] Inorganic N content in the soil could influence the maximum N fertilizer rate for obtaining maximum yield of spring cabbage significantly. The result indicated that the changes of soil inorganic N only affect N fertilizer application rate during the growing season. When the N fertilizer rate was 1.8-3.2 times of the N fertilizer rate for obtaining the maximum cabbage yield, the excess applied N rate has caused NO3^--N enrichment in the ground water, The N rate and inorganic N content in soil can affect the N utilization rate of cabbage, the cabbage-corn rotation system is good for enhancement of N utilization rate. When the N rate was at 90 kg.ha^-1, high-yield of cabbage and best-quality were obtained simultaneously. [Conclusion] Inorganic N content in soil effects the maximum N rate and the N utilization rate remarkably, The N fertilizer after-effect of Saijiang black soil is obvious, cabbage- corn crop rotation can raise N utilization rate. The N rate influences cabbage yield and the quality. In order to obtain better quality, N rate must be reduced.