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土壤中氮素的积累主要来源有四个方面:即动物残体的积累,有机或无机肥料的使用,土壤微生物的固定和随着大气降水进入土壤中的氮素。土壤中氮素的形态可分为无机态和有机态两种。被植物直接吸收利用的无机态 N 占全 N 量的5％左右,而绝大部分以有机态存在。有机态 N 在微生物的活动下逐渐矿化后,才能被植物利用。从现育的土壤肥力状况来看,70—80％的土壤都缺乏 N 素。所以说大部分土壤施用 N 肥都有显著的肥效。了解土壤全 N的含量,不但可能作为施肥参改,而且可以判断土壤肥力,拟定施肥措施。
There are four main sources of nitrogen accumulation in soils: accumulation of animal residues, use of organic or inorganic fertilizers, immobilization of soil microorganisms, and nitrogen that enters the soil with precipitation. Soil nitrogen forms can be divided into two kinds of inorganic and organic. The inorganic N directly absorbed by plants accounts for about 5% of the total N content, while most of them are in the organic state. Organic N is gradually mineralized under the action of microorganisms before it can be used by plants. From the status of fertile soil fertility point of view, 70-80% of the lack of N soil. So most of the soil application of N fertilizer has significant fertilizer effect. Understand the content of soil N, not only may be used as fertilizers to change, but also to determine the soil fertility, to develop fertilization measures.