Distribution of Water-Stable Aggregates in Some Soils of West Bengal in Relation to Organic and Inorganic Constituents

The role of different inorganic and organic constituents in soil aggregation was studied in nine different soil profiles. Cation exchange capacity and exchangeable cations played prominent role in aggregate formation in most of the soil profiles. A very close relationship existed between amount of free iron oxide and mean weight diameter (MWD), particularly in the alluvial and hilly soils. Amount of clay, rich in illitic mineral, showed a significant positive correlation with MWD. Significant and positive correlation also existed between sesquioxide and MWD of the alluvial soils. Role of organic matter was observed to be prominent in soil aggregation. Humic acid fraction was found to be effective in promoting aggregation, specially in such soils where organic matter was positively correlated with soil aggregation.