Characterization of Acidity in Acid Sulphate Soils of Kerala

The acidity characteristics of acid sulphate soils of Kuttanad, Kerala, were studied in detail by collecting surface, profile and subsurface soil samples from 20 locations of six soil series viz., Ambalapuzha, Purakkad, Thotapally, Thuravur, Kallara and Thakazhi that belonged to acid sulphate soils. The soils were extremely acidic showing a range of pH (H2O) varying from 2.5 to 5.2. Lowest pH was recorded by Thakazhi series and the highest by Thotapally. The potential acidity of soils ranged from 14.71 cmol·kg -1 to 110.5 cmol·kg -1 with Thakazhi series showing the highest value. The contribution of hydrolytic acidity to potential acidity ranged from 70.2% to 97.2%. In all soil series, exchangeable Al 3+ was greater than exchangeable H + . A significant correlation was observed among pH (KCl), pH (H2O) and pH (CaCl2) in all series.