MICROELEMENT CONTENT IN MIXED-GRASS HAY GROWN ON FOREST-STEPPE SOILS

Abstract

In the article, the data of research on the comparative assessment of microelement content in mixed-grass hay grown on light-gray, dark-gray, and podzolized chernozem soils of the Forest-Steppe zone are analyzed. The soil cover of the river basin is represented by light gray and dark gray podzolized loamy soils, as well as podzolized loamy chernozems formed on loess. These soils are characterized by the following: humus content in gray forest soils ranges from 2.1 to 2.4%, and in chernozems from 2.8 to 3.1%; soil acidity (pH) in gray forest soils varies from 5.3 to 6.2, while in chernozems from 6.5 to 6.8. The content of easily hydrolyzable nitrogen ranged from 92 to 140 mg/kg and from 137 to 154 mg/kg, available phosphorus from 183 to 210 mg/kg and up to 300 mg/kg, and exchangeable potassium from 62 to 75 mg/kg and up to 148 mg/kg, respectively, according to the studied soil types. It was established that the content of the studied microelements in these soils formed the following sequence by increasing concentration: cadmium < copper < zinc < lead. According to contamination levels, the soils were evaluated as follows: by lead content (1.5–2.2 mg/kg) — moderate; by zinc content (5–9 mg/kg) — low; by copper content (1.0–1.9 mg/kg) — low; by cadmium content (0.2 mg/kg) — moderate. The calculated toxicity coefficients of microelements were below the maximum permissible level of 1.0 and had the following ranges: for lead 0.26–0.20; for cadmium 0.18–0.07; for copper 0.048–0.043; for zinc 0.029–0.016. The content of microelements in mixed-grass hay formed the following sequence by increasing levels: cadmium < lead < copper < zinc. Copper content (1.38–4.76 mg/kg) did not reach optimal values, while zinc content (16.0–19.73 mg/kg) indicated good nutritional quality for animal consumption. The biological absorption coefficients of heavy metals varied within 0.8–1.97 for lead and 0.58–1.2 for cadmium, which confirms the low ability of mixed-grass vegetation to accumulate toxicants. Much higher absorption capacity was recorded for copper (9.52–33.52) and zinc (23.36–53.36).