Soil is one of the most important non-renewable basic resources on the earth’s surface.
The major soil groups of Tamil Nadu are:
- Red soils, (62 per cent)
- Black soils (12 per cent)
- Laterite soils (3 per cent) and
- Coastal soils (7 per cent)
The red soils are further classified as:
- Red loamy (30 per cent)
- Red sterile (6 per cent)
- Red-sandy (6 per cent)
- Thin red (2 per cent) and
- Deep red loamy soils (8 per cent)
As per the USDA system of soil classification (Taxonomy), the soils of Tamil Nadu are classified in to Six orders viz,
- Ultisols and
About 50 per cent of the total area of Tamil Nadu state is occupied by Inceptisol, 30 per cent by Alfisols, 7 per cent by Vertisols, 6 per cent by Entisols, 01 per cent by ultisols and very negligible area by Mollisols.
- Entisols : Young river alluvium, sandy and eroded red and laterite soils.
- Inceptisols: Moderately deep red, laterite and black soils are included under Inceptisol.
- Alfisols : Deep red and laterite soils
- Ultisols : Highly weathered laterite soils
- Vertisols: Deep black cotton soils and old alluvial soils are classified under vertisol.