The availability of potassium in soils to crops as measured by its release to a calcium-saturated cation-exchange resin

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Goulding, K. W. T. 1984. The availability of potassium in soils to crops as measured by its release to a calcium-saturated cation-exchange resin. The Journal of Agricultural Science. 103 (2), pp. 265-275.

AuthorsGoulding, K. W. T.

The amounts and rates of release of the different categories of soil K were measured on 21 soils from field experiments in England, Wales and West Germany using a calcium saturated cation exchange resin. The soils contained various amounts of exchangeable, fixed and matrix K; some contained no fixed K at all. These amounts could be qualitatively related to the clay contents of the soils.

Regression analyses of K removed at harvest by spring barley, winter wheat, field beans and sugar beet, grown in the field experiments, were made on the quantities measured by the Ca-resin method and on K exchangeable to M ammonium acetate (EK). The Ca-resin method proved a better predictor of K availability than EK for all four crops. A multiple regression of the amount and rate of release of exchangeable K, and the rate of release of fixed K, as measured by Ca-resin, gave the best correlation with K removed. The contribution of fixed K to the regression increased with the demand of the crop for K and with the length of time the crops had been grown without K fertilizer. For the cereals, fixed K appeared to be either completely available or unavailable depending on whether its rate of release exceeded a critical value characteristic of each crop.

The Ca-resin method is probably the best method available for measuring K reserves. It is, perhaps, too laborious for routine soil analysis, but could be used to characterize the long-term K release properties of a soil.


Year of Publication1984
JournalThe Journal of Agricultural Science
Journal citation103 (2), pp. 265-275
Digital Object Identifier (DOI)
Open accessPublished as non-open access
Output statusPublished
Publication dates
Print01 Oct 1984
Copyright licensePublisher copyright
PublisherCambridge University Press (CUP)

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