FIXATION OF POTASSIUM IN SOME CANADIAN SOILS

Abstract

From 16 to 71 per cent of the potassium added to surface samples of 11 Canadian soils was fixed upon wetting and drying into a form not extracted with 1 N neutral ammonium acetate. Fixation in several of the samples increased regularly with increase in their clay content. Samples exhibiting higher or lower fixing capacity than expected on the basis of clay content, usually had correspondingly low or high degrees of K-saturation. Considerable fixed potassium was removed by H-resin or by continuous leaching with 0.01 N HCl, and the rate of release by the latter was particularly high in Podzol samples.Liming of four of the acid samples, to raise the pH to about the neutral point, increased K-fixation slightly. Usually potassium in solution was lower in the limed than in the corresponding unlimed samples.Potassium from chloride and carbonate salts was fixed in similar amounts and there was no different effect of the anions on per cent K-saturation and [Formula: see text] ratio. The concentrations of potassium, and calcium plus magnesium in solution were higher, however, in the KCl- than in the K2CO3-treated samples.