The reserve and salt-replaceable acidity is always many times higher than the active acidity.Ī soil is acid when hydrogen ions predominate in the soil. Only the active acidity is measured in a routine pH determination. The reserve and salt-replaceable acidity controls the level of soluble or active acidity in the soil solution. The acidic cations adsorbed on the negative exchange sites are called the reserve (also residual or potential) and salt-replaceable (also exchangeable) acidity. Therefore, the nature of the exchangeable cations influences the composition of the soil solution. These exchangeable cations on the exchange complex are in equilibrium with the cations in soil solution. The Ca 2+, Mg 2+, K +, Na + cations, among others, are considered basic because they form strongly dissociated bases by reacting with OH –. The H + cations are acidic by definition, and Al 3+ cations are considered acidic because they react with H 2O to produce Al(OH) 3 and 3H +. Soil acidity is largely controlled by the composition of ions on exchange sites on the colloidal fraction. What influences how much material is needed to increase the pH of an acid soil?.List various soil amendments used to acidify a soil and reduce the pH.Write a chemical reaction depicting how a typical liming material (calcitic limestone, burned lime, etc.) act to neutralize acidity.List various soil amendments that are used to increase the pH of an acid soil?.Define active acidity, salt-replaceable (exchangeable) acidity, and residual acidity.How does buffering capacity relate to cation exchange capacity? ![]() ![]() List two negative consequences of high pH (basic) conditions in soil. List four negative consequences of low pH (acid) conditions in soil. ![]()
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