Influence of Different Forms of Iron and Aluminum on the Nature of Soil Acidity of Some Inceptisols, Alfisols, and Ultisols

Fifteen acid soils of Mizoram representing Ultisols and Inceptisols, and Madhya Pradesh, representing Alfisols, were studied to characterize the nature of acidity in relation to different forms of iron (Fe) and aluminum (Al). The mean contents of Fe and Al were extracted by various extracting reagents and were found to be in descending order as followed: dithionite>oxalate>pyrophosphate>ammonium acetate>KCl. The electrostatically bonded EB‐H+ and EB‐Al3+ acidity comprised 28.3 and 71.7% of exchangeable acidity whereas EB‐H+, EB‐Al3+, exchangeable, and pH‐dependent acidities comprised 9.8, 30.7, 40.5, and 59.5% of total potential acidity. All forms, of acidity showed significant correlation with pHk and organic carbon. Among the different forms, Fe and Al caused most of the variations in different forms of soil acidity but the effect of different forms of Al are more active and directly participate in the formation of EB‐H+, EB‐Al3+, and exchangeable acidity.