Effect of cation exchange on the distribution and movement of cations in soils with variable charge. I. Effect of lime on potassium and magnesium exchange equilibria |
| |
| Authors: | I. R. Phillips A. S. Black K. C. Cameron |
| |
| Affiliation: | (1) Australian Groundwater Consultants, 6/456 High Street, 3181 Prahran, Victoria, Australia;(2) School of Agriculture, Riverina-Murray Institute of Higher Education, 2650 Wagga Wagga, Australia;(3) Department of Soil Science, Lincoln College, Canterbury, New Zealand |
| |
| Abstract: | The influence of Ca(OH)2 on K and Mg exchange equilibria in three New Zealand soils was studied. Calcium hydroxide was mixed with each soil to raise the pH to about 6 or 7. For each Ca(OH)2 treatment, K and Mg exchange isotherms were determined, from which the equilibrium activity ratios were derived. Exchange coefficients and solution activity ratios were calculated according to the Gapon convention.The addition of Ca(OH)2 produced varying effects in the Gapon exchange coefficient for both K and Mg. The magnitude and direction of change in the exchange coefficient were related to the cation initially dominating the exchange sites, rate of Ca(OH)2 addition, soil colloids contributing to the CEC and specific interactions of Ca with these soil colloids.Addition of Ca(OH)2 reduced the equilibrium activity ratio of all soils. Changes in the bonding strength of K and Mg with increasing CEC were suggested as a possible mechanism for this decrease. |
| |
| Keywords: | Potassium magnesium calcium aluminium exchange coefficient equilibrium activity ratio organic matter bonding strength |
| 本文献已被 SpringerLink 等数据库收录！ |
|
