Mechanical Composition of Some Alluvial Soils of Northern India and their Comparison with Illite Clay

Alluvial soils collected from States of Gujarat, Punjab, Himachal Pradesh, Bihar and Madhya Pradesh are studied for mechanical and ultra-mechanical separates. Wide variation is noted in their minimum and maximum values. Parent material seems to be the main factor forvariation. Soils are found to be sandy to clayey in texture and low in ultra-clay fractions. Similarly six natural illite clays are analysed for conventional and ultra clay fractions. Two sets of values when recalculated on the basis of 2μ particles in the soils and clays are found identical; average b.e.c of the soils and clays also coincides. Thus alluvial soil clay is found to be predominantly illite clay.