ION PAIRS IN A SOLONETZIC SOIL

Abstract

The kinds and concentrations of the major ion pairs were determined in saturation extracts of 141 soil samples collected from a Solonetzic soil treated with various kinds of tillage combined with surface-applied chemical amendments. The correlations between concentrations of ion pairs and EC and pH of saturation extracts were statistically tested. Sulfate ion pairs NaSO4−, MgSO40 and CaSO40 occurred in relatively high concentrations. The other ion pairs were of low concentrations. Of the total soluble Ca, ion pairs ranged from 20.8% in the Ap horizon to 50.5% in the Csk horizon and Mg was approximately the same. The comparable values for Na were 0.8% and 4.6%, respectively. Ion pairs NaSO4−, KSO4−, MgSO40 and CaSO40 were significantly correlated with EC. Only carbonate ion pairs were significantly correlated with pH. Correcting concentrations of Na, Ca and Mg for ion pairs and activities changed considerably the SAR values in the Bnt1 horizon. Key words: Ion pairs, Solonetzic soils, ion activities