Sorption complex of selected soils of the Drawskie Lakeland

Abstract

Magnesium, calcium, potassium and sodium occur in soil in various forms but for plant nutrition their exchangeable forms are the most important. Cations bonded in soil colloids constitute a specific reservoir of nutrients. The aim of this research was to determine sorption properties and to evaluate the distribution of exchangeable cations in the profiles of soils of the Drawskie Lakeland. Samples were taken from 6 soil profiles formed from glacial till of the Baltic glaciation in the vicinity of Z³ocieniec and Czaplinek. In general, the sampled soils had the grain-size composition of loams. The reaction of most soil samples was acid. Exchangeable cations were extracted with the BaCl 2 solution according to PN-ISO 11260. The cation exchange capacity (CEC) ranged from 52.6 to 216.6 mmol(+) kg –1 of soil. The soils, despite acid reaction, were sorption-saturated. Alkaline cations were dominated by calcium, whose highest share in the sorption capacity was identified in the horizons of the parent material of all the examined soils. The lowest amounts of exchangeable calcium and magnesium were found in horizons Ap and Eet. The horizons rich in clay fraction contained higher contents of Ca 2+ and Mg 2+ , which was confirmed by significantly positive correlation. The acid reaction did not affect significantly either the content of exchangeable cations or their distribution in the soil profiles. The highest content of K + in arable-humus horizons of some of the soils can be related to potassium fertilisation and the weathering of minerals containing that metal. The highest content of magnesium and calcium cations in horizons Bg and the parent material of Gleysols point to the possibility of some overlapping of the top-down gleyic process features with lessivage features.