Liming effects on soil exchangeable and soil solution cations of 4 soil types in north-eastern Victoria

Abstract

The effects of lime additions on exchangeable and soil solution cations of four soil types in north-eastern Victoria are discussed. Liming significantly (P < 0.05) reduced the concentration of exchangeable (1 M KCl), extractable (0.01 M CaCl2), soil solution total and monomeric aluminium. Raising the soil pHCa to 4.8 decreased Ale, concentrations below 1 mg kg-1, Al saturation % of the effective cation exchange capacity below 5 and AlTot below 5 PM; and raising the soil pHCa to 5.8 decreased MnCa concentrations below 10 mg kg-1 and AlTot below 2µm on the four soil types used in this study. Grain yield responses were best described by the sum of the activities of the Al monomers. Where organic C was present, responses could also be attributed to the complexing of monomeric Al. Grain yield responses could not always be reliably predicted by the Al saturation % of the effective cation exchange capacity. Liming significantly (P < 0.05) increased the concentration of Ca in the ECEC, but the Ca activity was not well correlated with lime response for all sites. The In ratio of aCa2+/ÓaAl- mono shows promise in predicting negative responses to lime applications (with values > 6) where soil pHCa is less than 5. The combination of Ca activity and the sum of the activity of the Al monomers, together with organic C content, may provide a better description of the responsiveness of acid soils to lime applications.