Eleven groups of soil orders are found in Karnataka
Entisols, Inceptisols, Mollisols, Spodosols, Alfisols, Ultisols, Oxisols, Aridisols, Vertisols, Andisols and Histosols.
- Depending on the agricultural capability of the soil, the soil types are divided into six types viz., Red, lateritic(lateritic soil is found in bidar and kolar district), black, alluvio-colluvial, forest and coastal soils.
The common types of soil groups found in Karnataka are
- Red soils: Red gravelly loam soil, Red loam soil, Red gravelly clay soil, Red clay soil
- Lateritic soils: Lateritic gravelly soil, Lateritic soil
- Black soils: Deep black soil, Medium deep black soil, Shallow black soil
- Alluvio-Colluvial Soils: Non-saline, saline and sodic
- Forest soils: Brown forest soil
- Coastal soils: Coastal laterite soil, Coastal alluvial soil
These have been further divided into 11 sub groups. Red soils have 4 subgroups, Laterite soils have 2 subgroups, Black soils have 3 subgroups and alluvial soils have 2 subgroups (ICAR, 1980).
- Coastal laterite soils, alluvial soils and forest soils have no subgroups. The alluvial soils possess great natural fertility. These soils are suitable for the cultivation of a wide range of crops such as wheat, rice, sugarcane etc; nevertheless, at some places, gram, barley, maize etc are found to be the most common crops cultivated.
- The sandy soil consists of Aeolian sand (90-95%) and clay (5-10%). These soils are very light and comprise about 8.46% of the country’s soil cover. These are suitable for high salt tolerant crops, such as barley, rape and cotton, and also medium salt tolerant crops, such as wheat, millets, maize and pulses.
- The black soils vary in depth from shallow to deep. The typical soil derived from the Deccan Trap is theregur or black soil. Many black soil areas have a high degree of fertility, but some, especially in the uplands are poor. Black soils are highly argillaceous, very fine grained and dark and contain a high proportion of calcium and magnesium carbonates. They are exceedingly sticky, when wet. On drying, they contract forming large and deep cracks. These soils contain abundant iron, and fairly high quantities of lime, magnesia and alumina. They are deficient in potash, nitrogen and organic matter.
- The black soils of Karnataka are fine-textured with varying salt concentration. The soils are generally rich in lime and magnesia. The intensively cultivated tracts where adequate rainfall occurs are most suitable for cotton, wheat and jowar. But where irrigation facilities have been made available rice and sugarcane crops are also cultivated.
Red soil of Karnataka:
The predominant soil in the eastern tract of Karnataka is the red soil overlying the granite from which it is derived. In the districts of Bangalore, Kolar, Mysore, Tumkur and Mandya, this soil is found in varying depths. They occur as shades of red and pass on to yellow. Loamy red soils are predominant in the plantation districts of Shimoga and Hassan. They are rich in P 2 O 5 (0.05-0.3%) and their lime content varies from 0.1-0.8%. Nitrogen is below 0.1%. Iron and alumina is high, being 30-40%. A broad strip of area running between the eastern and western parts of Coorg is covered by red loam. A large variety of crops, such as paddy, jowar, ragi, and cotton, are grown under irrigation but crops such as millets, pulses and even gram are raised under rain-fed conditions.
Laterite soils occur in the western parts in the districts of Uttara Kannada, Dakshina Kannada, Shimoga, Hassan and Mysore. They support tea, coffee, rubber and coconut plantations. The traditional soil groups of Karnataka and the soils of the major landforms of Karnataka are given below.
South Deccan plateau-soil:
The soils of south Deccan Plateau are classified into two moisture regimes – ustic (deficient in water, but most of the water available comes from the cropping season) and aridic (highly water deficient). Ustic moisture regime covers major areas in the State except in parts of Bellary, Raichur, Chitradurga and Bijapur districts, which has an aridic moisture regime. The granite/gneiss landform covering an area of 8.1 Mha in Bangalore, Kolar, Tumkur, Mandya, Mysore, Hassan, Chikmagalur, Shimoga, Chitradurga, Raichur, Bellary and Gulbarga district is mostly covered with soils that are shallow to moderately shallow, excessively drained, gravely sandy clay in nature. The rolling lands have shallow to deep, somewhat excessively to well drained, red gravely loamy to clay soils. The soils of the valley are dominantly very deep, moderately well to poorly drained, fine textured and at places stratified. The major crops cultivated in these soils are rice and sugarcane.
The soils of the basalt landform cover an area of about 2.7 Mha in the districts of Bidar, Gulbarga, Bijapur and Belgaum. These soils are moderately to very strongly alkaline, slightly to moderately calcareous and have organic carbon of 0.33 to 0.63%.
Soils of laterite landform cover an area of 1.5 Mha in the districts of Bangalore, Kolar, Bidar, Gulbarga, Belgaum, Dharwad, Shimoga, Chikmagalur, Kodagu, Hassan and Uttara Kannada.
Soils of metamorphic landform cover an area of 2.7Mha running Northwest to Southeast within the granite and gneiss landforms in Tumkur, Chikmagalur, Chitradurga, Kolar, Mysore, Belgaum, Bellary and Raichur districts. The landform includes ridges, rolling lands and valleys. The ridges and the rolling lands have gravely loam to clay soils. Valleys have deep, poorly drained, calcareous, cracking clay soils. Soils of sedimentary landform cover an area of 0.8Mha in the districts of Gulbarga, Bijapur and Bidar (Soils of Karnataka, 1998-NBSS).
Soils of the Western Ghats covers an area of 2Mha in the districts of Belgaum, Uttara Kannada, Dharwad, Dakshina Kannada, Shimoga, Chikmagalur, Hassan, Kodagu and Mysore. These soils are generally dark brown to dark reddish brown and black in colour due to the accumulation of high organic matter under the forest cover. The Eastern Ghats covers an area of 0.4 ha in the districts of Mysore and Bangalore bordering Tamil Nadu. The soils are very shallow, somewhat excessively drained, gravely loam to clay soils. Soils of the West Coast cover an area of 0.7 Mha in the districts of Uttara Kannada and Dakshina Kannada.
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