Chemical studies on soil humic acids

Open Access
Publisher Website
Google Scholar
Abstract
The levels of amino acid, ammonia, amino sugar, hydrolysable-N, non-hydrolysable-N, and total-N in humic acids obtained from various soils were determined to investigate their relationships to the degree of humification (i.e. RF values) or the types of humic acids. The levels of total-N, hydrolysable-N. and amino acid-N increased from Rp(2) type (obtained from Ao layer humus or rotted plants) to Rp(1) type humic acids (from A layer or plowed layer soils), and then decreased with increasing RF values in the order of Rp(l), Po, B, and A type humic acids. Most of the nitrogen constituents are presumed to be mineralized during humification. Non-hydrolysable-N increased slightly, but its ratio to total-N increased with RF values especialIy among A type humic acids. Yields of ammonia by hydrolysis decreased with increasing RF values. The amino acid compositions of 4 ditTerent humic acids were similar, and the ratio of amino acid-N to total-N was relatively constant among highly humified A type humic acids, so that proteinous structures in humic acids were presumed to be relatively stable.

This publication has 6 references indexed in Scilit: