| Popis: |
Characterization of soil solution aluminum (Al) as a predictor of Al toxicity to plant roots growing in acid soils has received increasing attention during recent years. However, release of Al into soil solution may depend on several soil properties and the concentration of supporting solution employed for displacing soil solution. For this study the authors obtained subsoil samples of Bladen and Wedowee series from Georgia and a sample Podzolic soil from Australia. Soil solution was displaced by centrifugation following 4 h equilibration with deionized water or solutions of CaCl{sub 2}{center dot}2H{sub 2}O at 0.1, 1, 10, or 100 mM concentration. The pH and ionic strength of displaced soil solutions were not influenced by the concentration of CaCl{sub 2} in the supporting solution from 0 to 1.0 mM. However, the pH of soil solutions decreased while the ionic strength increased when the concentration of CaCl{sub 2} in the supporting solution was increased to 10 or 100 mM. Concentrations of Al in soil solutions displaced by water or 0.1-1.0 mM CaCl{sub 2} solutions were much greater in predominantly smectitic-Bladen soil than in kaolinitic-Podzolic or Wedowee soils, although exchangeable Al was 78% greater in the Podzolic soil and only 36% lower in themore » Wedowee soil than in the Bladen soil. Concentration of Al in soil solution rapidly increased along with a decrease in pH and an increase in ionic strength when soil solution was displaced using 10 or 100 mM CaCl{sub 2} solutions.« less |
