The nature of soil clays and the stability of microaggregates

The relative importance of the nature of clay fractions in the stability of microaggregates was investigated in the ferruginous soils, black soils and alluvial soils of India widely differing in their mineralogy. The influence of clay-iron oxide interaction was common in all these soils. However, the size range of stable aggregates depended on the dominant clay mineral, kaolinite influencing <50 µm aggregates and smectite in the formation of 250-1000 µm aggregates. The influence of cohesive forces between clay particles was more than the clay-iron oxide interaction in the smectitic soiIs.