Distribution of Different Forms of Aluminium in Clay Fraction of Paddy and Associated Non-Paddy Soils of Assam

Profiles of paddy and associated non-paddy soils of Jorhat (P1, NP1), Golaghat (P2, NP2), Sivasagar (P3, NP3) and Dibrugarh (P4, NP4) districts of Assam were investigated for different forms of aluminium (Al): total (Al t ), dithionite extractable (Al d ), pyrophosphate extractable (Al p ) and oxalate extractable (Al o ) in the clay fraction.Total Al (Al t ), dithionite extractable Al (Al d ) and oxalate extractable Al (Al o ) in clay fraction was slightly higher in paddy soils as compared to non-paddy soils whereas pyrophosphate extractable Al (Al p ) showed a reverse trend.Al d formed major portion of total aluminium content in clay fraction (Al t ) followed by Al p and Al o in both paddy and non-paddy soils.Crystalline aluminium oxide (Al d -Al o ), amorphous inorganic (Al o -Al p ) and silicate aluminium (Al t -Al d ) in clay fraction was found to be higher in paddy soils than non-paddy soils.Also, irrespective of the land use, the content of different forms of Al in the clay fraction was irregular with depth.Al d /Al t was found to be slightly higher in non paddy soil than that of paddy soil.Different fraction of organic carbon and the content of clay had a strong influence on the distribution of forms of Al in the clay fraction of soil.The results also revealed that there was equilibrium in different fractions of this element.