Gavva D. Agrogenetic and postagrogenetic evolution of typical (modal) chornozems of Left bank Forest-steppe of the Ukraine

The results of the complex field, laboratory and expeditionary researches, of physicochemical (cation-exchange), chemical, acid-alkaline, microbiological, micromorphological properties and dynamics of "effervescence line" in chornozem soils of the postagrogenetic and agrogenetic use, were presented in the thesis. It has been proven that the influence of forest vegetation on the agronomical characteristics of typical chornozems is almost identical to the action of grass fitocenosis. Theoretical generalizations and theory of the soil formation evolution under grass, artificial forest fitocenosis, and in agrocoenosiss were proposed. Systematic position of the forest agrogenetic soils in soil classification was found based on the elementary soil processes (ESP). It was proposed to classify forest chernozems and agrochernozems as a subtype in the soil classification of the Ukraine with their further subdivisions. Mathematical modeling of the typical chernozems evolution confirmed proposed hypotheses stating: a) agrogenetic soils (arable chornozems) develop under the unique pedogenesis fundamentally different from the steppe soil forming process; b) postagrogenetic soils (forming under grass or forest vegetation) develop after fundamentally different from agrogenetic pedogenesis; instead, they are similar to virgin soils that supports the proposed modifications in the soil classification. Received results are sufficient for developing projections of the further soil formation direction, change of fertility, and rational use recommendations development, especially during phytomeliorative works (grassing orafforestation).