ECOLOGICAL ASSESSMENT OF REPEATED CORN CROPS IN UKRAINE

Abstract

Overthe past 10 years, the area under corn in Ukraine has more than doubled and now stands at about 5 million hectares. At the same time, according to the results of scientific recommendations, the optimal area for sowing corn for grain and silage in Ukraine should be within 3 million hectares. Until now, the question of the optimal location of corn crops for grain in Ukraine is controversial. It is established that currently the placement of grain corn in the natural and economic zones of Ukraine does not fully ensure the effective use of bioclimatic and economic potential to increase grain production. And this, in turn, necessitates further improvement of the location of this culture in some regions of the country. Since modern crop rotations include a very limited set of crops: winter wheat, corn, sunflower, partly winter oilseed rape and soybeans, it is difficult to choose the optimal or even acceptable precursors for corn. Maize is often grown after winter wheat, but this precursor is lacking because it is used for sowing sunflower, winter oilseed rape and soybeans. If re-cultivation of other crops is not allowed, then corn can withstand such crops. Therefore, part of the corn crop is re-sown after corn for two or three or even more years. In repeated crops, the rate of application of mineral fertilizers can increase by 20-30%. Prolonged use of such mineral fertilizers can cause contamination of soils and products with heavy metals, nitrates and other toxicants, acidify or alkalize the soil reaction. Also, monoculture cultivation of corn causes deterioration of the phytosanitary condition of the agroecosystem, in particular the spread of pests, diseases, specific weed species resistant to herbicides. A problem that has spread in recent years is the intensive development of the meadow butterfly, which causes the complete destruction of corn seedlings. This requires intensifying the protection of corn from pests that also affect the ecological state of the agroecosystem.