| AbstractIt is well known that nitrogen is the most important nutritional element for plant grouth, and its deficiency occurs widespread, which seriously limits the plant production overall the world. This has led to widespread applications of N fertilizers allover the world, Excess inputs of N fertilizers, although strongly promoting crop production ,have already caused many serious problems: low economic return from the low recovery of N fertilizer by plants is one ,this has caused quality of production become very poor and evironmental pollution by leaching of nitrate or emission of nitrous oxide to the atmosphere is the other. These are very harmful to people's health. Great attention has been paid to solve this problem. For obtaining highly economic benefits and minimizing the pollution, application of N fertilizers shoued first be based on the N supplying important for making plan of application of N fertilizers. Total N and its availability of soil is decisive factors of N supplying capacity of soil . Organic matter and total N just are capacity index of soil nitrogen. Great part of soil nitrogen is organic forms .The mineralization of soil organic nitrogen is the major problem of N supplying capacity of soil .Many work has done on soil nitrogen mineralization .but seldom on characterization of soil nitrogen .The relation of mineralizable N to organic N components is the main purpose of this paper .In this paper, twenty five sarface soil samples taken form different sites and 36 soil samples form 6 layers of six types of soils were chosen as experimental soil samples. The mineralizable N was estirmated Through aerodic incubation and anaerobic incubation , and organic N components in soil had been determined through Bremner's method to study the relation minneralizable N to organic matter, and total nitrogen and arganic N components. The main results are as follows:1.The result of aeroblic incubation show:The mineralizable N was very well correlated with the organic matter or total N. The coefficent of determination was more than 0.6113 for organic matter and 0.5856 for total N, both being significant at 0.01 level .The amount of organic matter or total nitrogen was higher, the mineralizable nitrogen was higher too. but the ratio of the mineralized N to the organic matter or total N was not stable, so the organic matter and total N could not show the amount of mineralzable N of soil completely. Mineralizable N that just was part of organic matter and total N was very different in different soils, so was the ratio of mineralized N to the organic matter or total N. Mineralizable N was highly correlated with organic matter and total N, but even tightly correlelated with the easily mineralizable parts of organic matter and total N. 2.Although Mineralizable N came from the mineralization of soil organic N component, Mineralizable N was linearly correlated with total hydrolyzable N in aerobic incubation,the determination coefficients was more than 0.8446, but was no relation with the nonhydrolyzable N,The determination coefficients was blow 0.1167。 about the determination coefficients with amino acid N, ammonia N and Amino sugar N, it was 0.7625,0.7007 and 0.4649 respectively. The determination coefficients of hydrolyzable unknow N was 0.1625. By multiple regression ,only were Amino acid N and ammonia N the major contributor to the mineralized N, the hydrolyzable unknow N and amino acid N had no such character. 3. The results were same with Anaerobic incubatio and aerobic incubation to the relation of each organic components with mineralized N . Multiple regression and stepwise regression analysis result showed amino acid N was major contributor to mineralizable N, while ammonia N, Amino sugar N, unknown N had no such character. The result of path analysis showed that the direct path coefficient of Amino Acid N was 1.0222,compared with others, the coefficient was the largest and with a great contribution to compound Mineralizable N; The direct pat...
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