The cation exchange capacity and saturation of the sorptive complex with base cations are very important indicators for quality assessment of soils, because they define soil fertility and resistance to chemical degradation. The objective of the following study was to estimate the cation exchange capacity and saturation with exchangeable cations of Luvisols developed from loess, under agricultural use. The study comprised 12 pedons under winter wheat culture, classified into various complexes of soil suitability. Exchangeable cations of alkaline character were assayed with the Pallmann method in 1 mol NH4Cl dm-3 extract with pH 8.2. The content of cations Ca2+, K+ and Na+ was determined with a flame photometer, while that of Mg2+ was measured with the AAS method. In the Ap horizons of the analyzed soils, the quantitative sequence of base cations was most frequently Ca2+>Mg2+>K+>Na+. The total exchange bases (TEB) was favourable in most of the soils (3.8 - 16.9 cmol(+) kg-1), and the total acidity (TA) was varied (0.5 - 3.7 cmol(+) kg-1) but generally low. The cation exchange capacity (CEC) in the Ap, Et, EB, Bt and BC horizons of the soils was assessed as medium or high (5.2 - 17.9 cmol(+) kg-1). Only the C horizon, containing calcium carbonate, was characterised by very high CEC (76.2 cmol(+) kg-1). The base saturation (BS) was highly favourable in most of the soils (62.9 - 99.4%) and increased deeper into the pedon. The soils were characterised by generally favourable shares of particular cations: the percentage  of Ca2+ was 51.5 - 95.1%, most often higher than the optimum, while the shares of Mg2+ and K+ were slightly below the optimum. The calculated quantitative ratios between the cations showed very strong variation of values among particular pedons. The content of Mg2+ cations and the values of TEB and CEC in the Ap horizons of soils from the very good wheat complex were lower than in the Ap horizons of soils from the good wheat complex and the deficient wheat complex, whereas the levels of Ca2+, K+, Na+ and H+ as well as BS displayed only minor differences.

19.4.2014