COMPARISON OF PROCEDURES FOR ESTIMATING EXCHANGE PROPERTIES AND AVAILABILITY OF PHOSPHORUS AND POTASSIUM IN SOME EASTERN CANADIAN ORGANIC SOILS

Abstract

Determination of the cation-exchange capacity of 17 organic soils by the ammonium acetate method or by measurement of H replaced from HCl-treated samples by neutral 1 N NH4OAc, 1 N and 0.5 N Ba(OAc)2, and 0.5 N KOAc gave results which were closely related. The magnitude of the values varied with procedure, however, and 1 N Ba(OAc)2 gave the highest results.In a greenhouse experiment, the average uptake of potassium and of phosphorus by plants was higher at a soil temperature of 75° F than at 57° F. Percentage uptake of potassium by the plants was significantly correlated with the following criteria of potassium supply in the soils: exchangeable K, water-soluble K, [Formula: see text] and per cent K saturation. The corresponding percentage uptake of phosphorus was significantly correlated with the amounts of phosphorus extracted from the soils with 0.03 N NH4F + 0.1 N HCl, 0.5 N HOAc, water, and 0.5 M NaHCO3. The results indicated that water might serve as a suitable extractant of both potassium and phosphorus.