Relation of mineralizable N to organic N components

Six soils with different fertilities were sampled from 6 sites, each consisting of 6 layers, for studying the relation of mineralizable N to organic N components. The mineralizable N was estimated by aerobic incubation and the organic N components by Bremner's procedure. The results showed that the mineralized N was parallel to and very well correlated with the total acidhydrolyzable N. Among the hydrolyzable N, the amino acid N and ammonia N had a highly consistent correlation and were the significant variables in the multiple equations in relation to the mineralized N, showing their importance to the mineralizable N. Amino sugar N, on the other hand, had a relatively high correlation with the mineralized N, but was not significant in these equations. In contrast, the hydrolyzable unknown N had no such relations. Path analysis further indicated that the amino acid N and ammonia N had highly direct path coefficients to the mineralized N and made great contributions to the mineralized through the amino sugar N, but the amino sugar N had no such contributions though other components. Results obtained strongly suggested that the mineralized N was mainly from the hydrolyzable N, particularly the amino acid N and ammonia N, the latter two being the major sources for its production.