旱作物从土壤中吸收的氮素主要是硝态氮和铵态氮.一般茁壮生长的正常旱作物吸收铵态氮后即迅速参与蛋白质的合成,组织中积累的游离铵态氮很少,只有在生长不良,氮素转化作用阻滞时才有稍多的铵态氮存在,所以一般不用铵态氮作为作物氮素营养的指标。硝态氮虽然也很快地参与蛋白质的合成,但仍有相 The nitrogen absorbed by the dry crops from the soil is mainly nitrate nitrogen and ammonium nitrogen.Generally healthy crops that grow normally take the protein synthesis immediately after they absorb the ammonium nitrogen and rarely accumulate free ammonium nitrogen in the tissues , Only slightly more ammonium nitrogen is present only when the growth is poor and the nitrogen transformation is blocked. Therefore, ammonium nitrogen is generally not used as an indicator of crop nitrogen nutrition. Although nitrate nitrogen also quickly involved in protein synthesis, but there is still phase