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利用田间小区试验研究了小麦－玉米轮作中在不同施氮量和不同时期潮土1m土层中硝态氮的计中状况结果表明：3年不施氮肥的土壤仍有6～16kg／hm2的硝态氮，其中0～20cm土层占20％～34％．80％～100cm上层占10％～18％；每季施氨量小于225kg／hm2时．1m上层中各时期硝态氮含量变化不大，在11．4～41．3kg／hm2之间；当施氮量增加到375kg／hm2时，1m土层的硝态氮含量增加1．5～7．4倍，有7．4％～29．9％分布在0～20cm上层中，10％～16％分布在80～100cm上层中225kg／hm2对作物斋求及对土壤环境来说是一个合理的施只量。
The field experiment was conducted to study the N content of nitrate nitrogen in 1m soil layer of wheat-corn rotation under different nitrogen rates and different periods. The results showed that there was still 6 ~ 16kg / hm2 Nitrate, of which 0 ~ 20cm soil layer accounted for 20% to 34%. 80% ~ 100cm upper layer accounted for 10% ~ 18%; quarterly ammonia consumption less than 225kg / hm2. The content of nitrate nitrogen in 1m upper layer changed little from 11.4 to 41.3kg / hm2. When the nitrogen application increased to 375kg / hm2, the nitrate nitrogen content in 1m soil increased 1.5 ~ 7.4 times, 7.4% ~ 29.9% distributed in 0 ~ 20cm upper layer, 10% ~ 16% distributed in 80 ~ 100cm upper layer 225kg / hm2 for crop fasting and the soil environment is a A reasonable amount of Shi.