Question.
What are black soils? Describe their formation and characteristics.
(Chapter 6 Soils, Class 11 NCERT geography "India Physical Environment")
Answer.
Black soil is also called 'regur soil' or 'black cotton soil'. In the soil classification of the world, black soil comes under Chernozem soil. Black soil is black in color and is generally smooth (fine-grained), deep and impermeable.
The black color is due to the presence of iron, magnesium, and alumina in the soil. The black color is also due to the presence of organic carbon in the soil. The color of black soil ranges from dark black to grey.
Geographical distribution of black soil;
Black soil covers most of the Deccan plateau and the upper reaches of the Godavari and Krishna river basins.
Black soil is found in parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, and Tamil Nadu.
Black soil is deep in the upper part of the Godavari and Krishna valleys as well as in the north-western part of the Deccan plateau.
Formation of black soil;
Black soil is formed after the weathering of basaltic rocks present in the Deccan plateau. Basaltic rocks are volcanic rocks. Therefore, black soil is formed from volcanic basaltic rocks.
Characteristics of black soil;
Black soils are generally smooth (fine particles), deep and impermeable.
During the rainy season, it becomes sticky and becomes soft. During the dry season, wide cracks develop in the soil. This type of soil is called "self-plowed".
Black soil retains moisture for a very long time due to the slow absorption of moisture and a slow loss of moisture. Due to its long moisture retention properties, it helps in growing crops even in rainfed areas during the dry season.
The chemical composition of black soil is rich in lime, iron, magnesia, and alumina. Black soil also contains potash but lacks phosphorus, nitrogen, and organic matter.
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