Change in physical and chemical fertility indices of chernozem podzolized in crop rotation depending on fertilizer option

The article presents the research results of the impact of various doses and ratios of mineral fertilizers on the physical and chemical indices of podzolized hard-loam chernozem in Right-bank Forest-steppe of Ukraine. Based on the conducted researches, it was found that during the prolonged application of mineral fertilizers, the tendency toward soil acidification at 0.1-0.3 units of рНKCl is observed. In some variants of the experiment, рНKCl was <5,5, which testifies to the subacidic reaction of the soil solution. Therefore, in the future, the soil will require the liming keeping up. Prolonged application of mineral fertilizers in the crop rotation along with the exchange, also affects the change of hydrolytic soil acidity. At the same time, it significantly depends on the doses and ratios of fertilizers. Changes in hydrolytic acidity in the soil layer of 0-20 cm were in the range from 2.78 resin/kg before laying out the experiment to 4.23 resin/kg of soil. The greatest impact on its increase was the use of nitrogen and potash fertilizers. Magnesium content in SAC was more stable, even with high doses of mineral fertilizers, only a tendency to reduce its content was noted. Similar changes were observed in the content of the amount of cations K + Na in SAC. In the soil layer of 20-40 cm, changes in the cation content in SAC were less considerable, but a significant decrease in their amount was carried out in experimental variants where nitrogen fertilizers were introduced in a dose of 150 kg/ha a. i., and also in the background of the average annual application of P60K80 only in the rotation. The capacity of soil absorption under the influence of fertilizer does not change significantly, while the degree of bases saturation decreased from 89.9% to 83.7-88.8% in the soil layer of 0-20 cm and from 93.2% to 86.6-90.9, % in the soil layer of 20-40 cm depending on the fertilizer option. Thus, even chernozem soils, which are naturally neutral, cannot withstand chemical stress and change their physical and chemical properties in the process of agricultural use, provided that they are used only for mineral fertilizers.