Nature of Acidity in Some Alfisols and Inceptisols of Birbhum District of West Bengal

Twentyone acid soils ranging in pH from 5.4 to 6.3, collected froin Alfisols and Inceptisols zones of Birbhum District in West Bengal were characterized for the kinds of acidity and their relation with other soil properties. The exchange acidity due to H⁺ and Al³⁺ contributed only 15.8 to 47.2 per cent whereas, the pH-dependent acidity constituted 52.8 to 84.2 per cent of total acidity and was mainly associated with free oxides of Fe, Al and clay. Further, pH_w and pH_KCI showed negative relationships with all types of acidities. Aluminium saturation was found to be increased with increase in total acidity whereas calcium saturation had a reverse trend. All forms of acidity were significantly correlated with organic carbon, exchangeable AP+, extractable AP⁺ and clay content.