Well-known soils in India are clay and sand soils with varied porosity and varying degrees of permeability. The sandy soils in India have a low permeability and good water holding capacity, while the clay soils are porous and retain moisture well. These two soils can be differentiated on the basis of their porosity and permeability.
Sand-rich soils in India are generally divided into three categories – gypsum, perlite and the silica sand. Gypsum is a light clay and is commonly found in coastal area. Perlite is a sedimentary rock that is rich in calcium, magnesium, iron, zinc, manganese, coal, and a variety of trace elements. Silica sand is coarse sand and contains a high amount of potassium, sodium, and aluminum. All these three soils are suitable for agriculture.
Loose soils in India are classified into three categories – red, dry and yellow soils. Red soils are productive and are formed through intense heat or high pressure. Yellow soils are generally formed through flash evaporation and show a gradual texture. The dry soils in India are gypsum, clay and fine sands; while the soluble salts present in the red soils are aluminum, potassium and sodium.
A suitable crop suitable for soils in India consists of one or more layers having suitable soil characteristics. Soils with clay-like or fine-grained characteristics are suitable for producing clay products like pottery, metal goods, soap, and leather. Soils with marbled or complex textures are suitable for producing fine textured products like rice and wheat. Thus, there is a great demand for fertile soils in India. The soils in India are categorized as follows:
These classifications help to determine the suitability of an area for various crop growing seasons and climates. For example, the semi-sloping areas in northern India with higher altitude should be suitable for all kinds of crops growing across the year. Similarly, in the eastern parts of the country, the most suitable areas for intensive agriculture are the flat areas with low slopes. The main types of alluvial soils in India are:
Different soil types in India are characterized by varying land drainage, soil elevations, climate, fertility, soil characteristics, soils’ pH and the occurrence of plant species. In areas where there is enough and appropriate rainfall, the soil is well drained, and its moisture level is maintained through evaporation. This type of soil is known as saturated clay and has the most significant biological activity, and thus plays a major role in Indian agriculture.
The soils with adequate and suitable water-holding capacity are known as limy soils. Limy soils are those with a fine to medium texture and a dark green colour, which are rich in organic substances. The clay-rich limy soils are usually drained and have good water-holding capacity. On the other hand, the more permeable soils are known as silt soils in India, and these are found in most of the Northern regions. These soils are drained and have good water holding capacity; however they are colourless and cannot bear plant growth due to lack of sufficient moisture.
Organic soils in India are found in every region of the country, with the exception of the North East monsoon zone, which is totally devoid of any. There are also sand soils in the Western Himalayas, which are rich in both organic and inorganic nutrients. In central India, clay soils are the dominant type of soil, which is quite suitable for a variety of crops. Clay soils are not well drained but are rich in organic contents, and therefore yield better than silt-based soils. Thus, according to one estimate, an area of about 13 million square kilometres, including about three-fourths of India, has clay soils.