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采用田间实验研究了施用氮肥对设施条件下大青菜生长发育和产量,以及对土壤硝酸盐含量累积分布的影响。结果表明,在施氮肥0~500 kg hm-2范围内,氮肥施用量越大,产量越高,但到达一定量时,便不能再促进产量的提高,反而会引起减产。土壤铵态氮含量随着土壤剖面向下不断下降,表层的铵态氮含量较高,土壤硝态氮含量在整个土壤剖面的分布变化较小,但也是从表层向下处于一种缓慢减少的趋势,铵态氮的累积主要集中在上部土壤剖面,硝态氮的累积分布在整个土壤剖面,土壤硝态氮含量随施肥量增加而增加;氮肥施用量对硝酸盐含量有很大影响。在施氮肥0~700kg hm-2范围内,氮肥施用量越多,大青菜硝酸盐含量越高。
Field experiments were conducted to study the effects of nitrogen application on the growth and yield of Chinese cabbage and the cumulative distribution of nitrate in the soil. The results showed that in the range of 0 ~ 500 kg hm-2 of nitrogen fertilizer, the higher the application of nitrogen fertilizer, the higher the yield, but when it reaches a certain amount, it can no longer promote the yield increase, but will cause the yield reduction. The content of ammonium nitrogen in soil decreased continuously with the soil profile down, the content of ammonium nitrogen in surface layer was higher and the distribution of nitrate nitrogen in soil changed little in the whole soil profile, but also decreased slowly from the surface In the trend, the accumulation of ammonium nitrogen mainly concentrated in the upper soil profile. The accumulation of nitrate nitrogen was distributed in the whole soil profile. The content of nitrate nitrogen in soil increased with the increase of fertilizer application. The application of nitrogen fertilizer greatly affected the nitrate content. In the range of 0 ~ 700kg hm-2 of nitrogen fertilizer, the more nitrogen fertilizer, the higher the nitrate content of big greens.