Abstract
Increasing of soil fertility in the Southern Steppe subzone, as in Ukraine as a whole, is oneof the most important fundamental problems of nowadays, the solution of which will ensure the longtermsustainable development and high productivity of agro-ecological systems while preservingagricultural agro landscapes and, above all, their soil cover. One of the main directions that contributeto the production of stably high crop yields in the Southern Steppe subzone is the optimization of thestructure of the sown areas and the increase of the fertility of degraded soils. The specified problem issolved by means of long-term bean grasses and legumes-cereal grass mixtures or reforestation. In thisregard, the Institute for Irrigated Agriculture of the National Academy of Sciences has conducted thelong-term research on the selection of leguminous perennial grasses and legume grass mixtures, whosebiological features have been most adapted to the natural and climatic conditions of the subzone of theSouthern Steppe and contributed to the fixation of atmospheric nitrogen from the air. The creation ofhigh-yield single-species crops of leguminous perennial grasses and binary legume grass mixturesincreases the fodder base for animal husbandry, reduces the mineralization of humus in soils, improvestheir physical and physico-chemical properties and, above all, reduces the catastrophic impact of naturalphenomena associated with regional climate changes.