Based on particle size, the soils can be classified as under, adopting the IS soil classification system:
0.002 0.075 0.425 2.36 4.75 20 80 300
mm mm mm mm mm mm mm mm
All soils, as per the Indian Soil Classification System, are divided into three main groups:
(a) Coarse-grained soils, having more than half the total material by weight, larger than 75 micron sieve size.
(b) Fine-grained soils, having more than half the total material by weight smaller than 75 micron sieve size.
(c) Highly organic soils: these soils contain larger percentages of fibrous organic matter such as peat and particles of decomposed vegetation. Further, certain soils containing shells, concretions, cinders and other non- soil materials in sufficient quantities are also involved in this group.