FREE AND RELATED AMINO ACIDS IN THE SOILS OF FOREST-STEPPE OF VOLGA REGION AND ITS ROLE
The article presents the results of studying the amino acid composition in the prevailing soils of the region (RT): sod-podzolic, gray forest, brown-gray, leached chernozem. Free and related amino acids are identified, their quantitative indicators are given. A study of the qualitative composition of free amino acids in the soils of the region showed that they are close in the qualitative composition of amino acids, but differ in their quantitative content. The total content of free amino acids is 4-20 mg/kg and increases in the series of soils: sod-medium podzolic, brown-gray, gray forest and leached chernozem. Moreover, there are significant differences in the content of individual groups of free amino acids: in all soils, most of the free amino acids are represented by neutral and basic amino acids (65-80%), much smaller by dicarboxylic (11-29%) and cyclic (5-11%). Easily and hardly hydrolyzable fractions of organic nitrogen are the closest reserves of nitrogen available to plants. Identification of the amino acid composition of these nitrogen fractions showed that the qualitative composition of bound amino acids is almost the same as free. In the studied soils, 19-31% of nitrogen of easily hydrolyzable and 33-60% of nitrogen of hard hydrolyzable fractions are represented by amino acid nitrogen. At the same time, 40-54% of the total amount of nitrogen of amino acids falls on the share of neutral, and 14-28% - on the share of basic amino acids. Their content naturally increases from sod-podzolic to gray soil and to chernozem, both in the composition of easily hydrolyzed and difficultly hydrolyzed fractions, which indicates an improvement in the quality of nitrogen in this direction.