Nature of soil acidity in relation to different forms of iron and aluminium of some alfisols of West Bengal

Acid soils of West Bengal, belonging to the order Alfisols, were studied to characterize the nature of acidity in relation to different forms of iron and aluminium. The mean contents of iron and aluminium, extracted by various extracting reagents, were found to be in the following descending order: Dithionite > oxalate > pyrophosphate > KCl > ammonium acetate. The electrostatically bonded EB-H+ and EB-Al3+ acidities constituted 32 and 68%, respectively of exchangeable acidity while EB-H+, EB-Al3+, exchangeable and pH-dependent acidities comprised 7, 15, 22 and 78%, respectively of total potential acidity. Correlation between different forms of acidity and Fe and Al in soils suggested that the effect of different forms of Al was more dominant, which directly participate in the formation of different forms of acidity.