Laterite soil is rich in aluminium
, formed in wet and hot tropical areas. Almost all laterite soils are red due to the presence of iron oxides. It is prepared by the prolonged and rigorous weathering of the parent rock. Laterisation or tropical weathering is a long-drawn-out process of chemical and mechanical weathering which results in a large variety in the chemistry, grade, thickness and ore mineralogy of the ensuing soils. Laterite soils are pregnant with aluminium and iron oxides, but are deficient in potash, phosphoric acid, lime and nitrogen.
Laterite soil in India is mainly found capping the flat uplands, and is also spread in the western coastal region, getting incredibly heavy rain. Lateritic soils are also abundant in area along the edge of the plateau in the east, covering small parts of the states of Tamil Nadu
and a small portion of the Chota Nagpur Plateau
in the north and Meghalaya
in north-east. Laterite soils are habitually poor and can hold only scrub forests and pastures. Among the mixed types of soils, two groups are more substantial. They include the desert soils of western Rajasthan and mountain soils of the Himalayas.
Laterite soil is primarily found in the tropical regions which receive heavy seasonal rainfall. High rainfall encourages the leaching of soil where lime and silica are leached away and a soil rich in oxides of aluminium predominate and abundance laterite is called bauxite. Due to the presence of iron oxides the colour of laterite soil is basically red. This soil is poor in lime content and hence it is acidic. Laterite soils are found on the high level plateau and hilly areas that receive high rainfall and are specifically well developed on the Eastern Ghats in Orissa
. It is also found in the southern regions of the Western Ghats including the adjoining coastal regions in Ratnagiri District
Humus is almost absent in this type of soil. However, in the laterite soil developed in the forested areas in the western part of Karnataka
state, humus is present. Further, laterite soils of high level areas are very poor and least retentive of moisture and at times barren. But, in the low lying areas, regular addition of soils that are washed down from the adjacent higher areas affects lateritisation. In those areas, the lateritic soil being either mud or loam is useful and is regularly ploughed. For the continuous cultivation of crops, regular application of fertilizers is required. Laterite soil is found in different parts of India including the Eastern Ghats, Rajmahal hill
, Western Ghats, Maharashtra
, Orissa, Karnataka, West Bengal
, Tamil Nadu, Assam
, etc. Laterite soil is also widely found around the Satpura, Vindhyan Plateau, Maikal and Mahadeo ranges in Madhya Pradesh.