A simple method to determine the reactivity of calcium carbonate in soils

Determination of soil carbonate is important for numerous chemical and physical soil processes in arid and semi-arid zones. Here, we modify a conventional method to more easily determine active CaCO₃ (ACC) fraction in soils. Unlike the conventional method where the oxalate used up after reaction with carbonate is determined by titration with KMnO₄, the proposed method uses the difference between total carbonate analyzed before and after reaction with oxalate to determine ACC. The method compared well to the conventional approach; the procedure was faster, did not require KMnO₄, and appeared to be unaffected by exchangeable Ca. The proposed method is well-suited for samples across a wide range of total carbonate.