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Potassium: calcium exchange in soils of the Broadbalk experiment at Rothamsted

Published online by Cambridge University Press:  27 March 2009

T. M. Addiscott
Affiliation:
Bothatnsted Experimental Station, Harpenden, Herts.

Summary

Soils from Broadbalk field were used to find whether differences in K-manuring had altered K:Ca exchange relationships during 100 years cropping with wheat, by measuring cation exchange capacities and quantity/intensity (Q/I) relationships.

Cation exchange capacities (CECs) were measured with and without the contribution of the soil organic matter and the following mainly non-significant trends arose during 100 years: (1) The CECs of plots given K fertilizer increased slightly when the organic contribution is included and decreased slightly when it is not. (2) The CEC of the plot given farmyard manure increased greatly when the organic contribution is included and decreased slightly when it is not. (3) The CEC of the unfertilized plot increased very slightly, whether or not the organic contribution is included.

The K buffer capacity, the slope of the Q/Icurve when the soil neither gains nor loses K, was related to the K saturation of the CEC better when the organic contribution was omitted from the CEC than when it was included, suggesting that K: Ca exchange measured by the Q/Icurves occurs mainly on the non-organic part of the CEC. Two soils depleted of K had anomalously large buffer capacities, but two undepleted samples behaved similarly.

Superimposing Q/Icurves by eye showed no appreciable differences between samples from different years or from different plots, even at large activity ratios. Plotting exchangeable K against I0, the activity ratio when the soil neither gains nor loses K, gave a single curve embracing all plots from all years, similar to the superimposed Q/I curves. Long–term manuring with ammonium sulphate has not affected K–Ca exchange.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1970

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References

Addiscott, T. M. (1970a). The potassium Q/I relationships of soils given different K manuring. J. agric. Sci. Camb. 74, 131–7.CrossRefGoogle Scholar
Addiscott, T. M. (1970b). A note on resolving soil cation exchange capacity into ‘mineral’ and ‘organic’ fractions. J. agric. Sci., Camb. 75, 365–7.CrossRefGoogle Scholar
Addiscott, T. M. & Taxibtoeen, O. (1969). The buffering capacity of potassium reserves in soils. Potash Rev. Subject 4, 45th suite.Google Scholar
Barshad, I. (1954). Cation exchange in micaceous minerals. I. Replaceability of the inter–layer cations of vermiculite with ammonium and potassium ions. Soil Sci. 77, 463–78.CrossRefGoogle Scholar
Bascomb, C. L. (1964). Rapid method for the determination of cation exchange capacity of calcareous and non-calcareous soils. J. Sci. Fd Agric. 15, 821–3.CrossRefGoogle Scholar
Beckett, P. H. T. (1964). The immediate Q/Irelations of labile potassium in the soil. J. Soil Sci. 15 (1), 923.CrossRefGoogle Scholar
Beckett, P. H. T. (1965). Activity coefficients for studies on soil potassium. Agrochimica 9 (2), 150–2.Google Scholar
Beckett, P. H. T., Craig, J. B., Nafady, M. H. M. & Watson, J. P. (1966). Studies on soil potassium. V. The stability of Q/I relations. Pl. Soil 25, 435–55.CrossRefGoogle Scholar
Beckett, P. H. T. & Nafady, M. H. M. (1967a). Studies on soil potassium. VI. The effect of K fixation and release on the form of the K: Ca + Mg exchange isotherm. J. Soil Sci. 18 (2), 244–62.CrossRefGoogle Scholar
Beckett, P. H. T. & Nafady, M. H. M. (1967b). Effect of K release and fixation on the ion-exchange properties of illite. Soil Sci. 103, 411–16.CrossRefGoogle Scholar
Beckett, P. H. T. & Nafady, M. H. M. (1969). The effect of prolonged cropping on the exchange surfaces of the clays of Broadbalk field. J. Soil Sci. 20 (1), 110.CrossRefGoogle Scholar
Deist, J. & Talibudeen, O. (1967). Ion-exchange in soils from the ion pairs K—Ca, K—Rb and K—Na. J. Soil Sci. 18 (1), 125–37.CrossRefGoogle Scholar
Johnston, A. E. (1969). Plant nutrients in Broadbalk soils. Rep. Rothamsted exp. Stn for 1968, Pt II, pp. 93115.Google Scholar
Johnston, A. E. & Garner, H. V. (1969). Broadbalk: historical introduction. Rep. Rothamsted exp. Stn for 1968, Pt II, pp. 1225.Google Scholar
Newman, A. C. D. & Brown, G. (1966). Chemical changes during the alteration of micas. Clay miner. 6, 297310.CrossRefGoogle Scholar
Schofield, R. K. (1947). A ratio law governing the equilibrium of cations in the soil solution. Proc. 11th int. Congr. pure appl. Chem., London 3, 257–61.Google Scholar
Tinker, P. B. H. (1964). Studies on soil potassium. III. Cation activity ratios in acid Nigerian soils. J. Soil Sci. 15 (1), 2434.CrossRefGoogle Scholar