COMPOSITION AND DYNAMICS OF EXCHANGEABLE CATIONS IN COMMON CHERNOZEM ENRICHED WITH HUMIC PREPARATION
The article presents findings on the composition of the soil-absorbing complex and the content of absorbed cations of common carbonate chernozem under winter wheat. The studied soils are located in a dry steppe zone with an arid moderately hot continental climate. The soil absorbing complex contains almost all the cations necessary for plant nutrition. Nutrients are sorbed on the surface of mineral and organomineral particles, being fixed in the soil profile. The amount of absorbed bases in the arable layer varied within 26.52-29.97 mg-Eq per 100 g of soil. Among the exchange bases calcium cations prevailed - 22.98-23.85 mg-Eq per 100 g of soil or 86.8-87.4% of the total exchange bases. The content of absorbed magnesium was 2.70 - 3.39 mg-Eq per 100 g of soil or 11.3-11.8%. The content of absorbed sodium did not exceed 1.4% of the total exchange bases, which indicates the absence of solonetz processes in the soil. The dynamics of the content of exchangeable cations in experiment with the humic preparation Bio-Don on winter wheat Donskaya Lira is seasonal, the treatment with the preparation did not significantly affect the composition of the absorbing complex. A decrease in the content of exchange bases in the soil absorbing complex in spring after heavy rainfall was recorded. In summer the content of exchange bases increases, and the calcium content exceeds the autumn level, while the content of magnesium and sodium decreases. The studied chernozems have a neutral and slightly alkaline reaction of the medium. The humus content is subject to seasonal fluctuations, decreasing towards the end of the growing season.