Free Amino Acids in Eroded Typical Serozem Soil of Uzbekistan.
Laziza Gafurova, Tashkent State Univ of Agriculture, University str. 1, Tashkent, Uzbekistan
Amino acids, either in a free or polymeric state, represent a significant addition of N to most ecosystems. Therefore comprise a key pool in the soil nitrogen cycle. The existence of amino acids in greater or smaller quantities, their qualitative contents, is linked to fertility, raising the level of crop yield. The free amino acids content of the soil is strongly influenced by weather conditions, moisture status of the soil, type of plant and stage of growth, additions of organic residues, and cultural conditions. Through recent studies, it has become evident that soil amino acids are a principal source of nitrogen for certain plants. The aim of this study was to study free amino acid content in soil with different depth. We examined soil amino acid content from eroded serozem soils of north east Uzbekistan. The spectrofhotometric procedure was used to determine free amino acid concentrations in soil. Generally, the concentration of free amino acids in soil solution was low. In studied soils twenty amino acids were found: aspartate, glutamate, serine, glycine, tyrozine, valine, metionine, cistine, isoleycine, leycine, fenilalanine, triptophan, lyzine. The results indicate that in studied soils in the upper horizon (0-15 cm) contains about 28 % of dicarbon amino acids, 39 % of neutral acids, 8 % of cyclic acids, 15 % of diaminocarbon acids, 8 % of oxyamine acids, up to 1 % of sulphur containing acids. In the lower horizon (30-50 cm) the content of amino acids decreases by 2,5-3 times respectively. Some of amino acids (serine, glycine, proline, arginine, tyrozine, leycine isoleycine are found just as “traces”. The aspartate and glutamate, alanine, lyzine, treonine, valine are observed in small quantities. Amino acids in soils with deeper levels decrease in a smoother way. This phenomenon positively correlates with influence of erosion processes to the content of humus, soil texture, nitrogen and micro flora of soils. It has been found under field conditions that the amount and composition of free amino acids in studied soils as dynamic characteristic and changes essentially under the effect cultivation application of fertilizer and crop production.