Studies in soil potassium

Summary The Quantity-Intensity relations of labile K in soil relate the intensity (or availability) of labile K to the amount of labile K present. Several soils have been depleted of K by crops, and enriched or depleted of K by other means. Theforms of the Q/I relations for labile K in these soils are almost unaffected by K-depletion, by the fixation of added K on storage, or by the release or fixation of K by heating. The addition of very large amounts of K may cause transient changes, but these changes disappear on storing the soil.So under field conditions depletion of K or Ca + Mg by crops, and the addition of K in fertilisers, are unlikely to alter the form of the Q/I relations of labile K.The release of fixed K from depleted soils was very slow unless the depleted soils were heated. Fixation of added K was more rapid.