Black cotton soil is medium to high compressibility inorganic clays and constitutes the main group of soils in India. They are characterized by high shrinkage and swelling properties. Because of their high swelling and shrinkage characteristics, black cotton soils have been a problem for road engineers.
Black cotton soil – heavy clay soil ranging from clay to loam; It is usually light to dark gray in color. Cotton grows on such soils. Soils are predominantly found in the central and southern parts of India.
Black / regular soils are located in areas covered with lava and these soils are called “regur” and are commonly known as “black cotton soils”.
This is because the soil is mainly used to grow cotton crops. Mineral composition of black cotton soil:
|Iron oxide||(9-10) %|
|Lime and magnesium carbonates||(6-8) %|
|Phosphate, nitrogen, humus||low|
Characteristics and colour of the black cotton soil
Black cotton soil – highly clayey soil. The black color of black cotton soil is due to the presence of a low concentration of titanium oxide. Soil has a high percentage of clay that is predominantly montmorillonite in structure and is black or blackish gray in color.
Cotton consumes huge amounts of water, causes soil erosion and degradation, and uses more insecticides and pesticides than almost any other crop. Another major problem with cotton is its impact on the soil. Because cotton requires a lot of water to grow, this causes problems with the soil in which it grows.
Black cotton soils are composed of various properties of minerals such as montmorillonite and kaolinite, chemicals such as iron oxide and calcium carbonate, and organic matter such as humus. Montmorinolite is the predominant mineral in black cotton soils.
Types of black cotton soil
By power, chernozem is divided into:
- Shallow chernozem.
- Medium black soil.
- Deep black soil.
Shallow chernozem: This type of soil is suitable for growing wheat, cotton, and rice. Mostly they are found less than 30 cm thick.
Middle black soil: Its thickness ranges from 30 cm to 100 cm.
Deep black soil: Its thickness is measured over 1 meter and is found in lowlands.
Deep black soils are very fertile and are suitable for growing rice, cotton, sugarcane, citrus fruits, etc. They contain 40-60% clay.
Revealing black soil in the field
- It is black.
- It is a very small particle that cannot be seen with the naked eye.
- Large cracks form in summer.
- It looks cloudy in the rainy season.
- It is sticky when wet.
Benefits of black soil:
- Since they are very fertile in nature, they are very useful in cultivation.
- They are resistant to wind and water as they have a grain-like structure rich in iron.
- Chernozem retains moisture well, so it can help in rainfed agriculture.
- The cracks formed by the black earth can be used as a passage for rainwater.
- It has a high dry load bearing capacity.
Disadvantages of black soil:
- it loses its load-bearing capacity when it gets wet.
- Due to the swelling and drying out of the soil, it is very difficult to cultivate.
- Construction on this soil is unsafe, as its volume increases from 20% to 30% of the original, which causes cracks in the foundation.
- High stabilization should be done for any construction as it has unusual characteristics.
What can be grown on black cotton soil?
Black cotton Soi is ideal for growing cotton, sugarcane, tobacco, wheat, millet, and oilseeds. Black soil is the best type of soil for growing cotton. Besides cotton, it is also suitable for growing grains, oilseeds, citrus and vegetables, tobacco, and sugarcane.