Black soil, also known as Regur or Black Cotton Soil, primarily forms from the weathering and denudation of volcanic rock (basalt) or the cooling and solidification of lava after volcanic eruptions. These mineral-rich soils are prevalent in regions like the Deccan Plateau in India.
Here's a breakdown of the formation process:
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Source Material: The primary source is basalt rock, a dark, fine-grained volcanic rock rich in minerals like iron, aluminum, and magnesium.
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Weathering: Over extended periods, the basalt rock undergoes weathering, a process where rocks are broken down into smaller particles due to physical, chemical, and biological factors. Physical weathering includes temperature changes and abrasion. Chemical weathering involves reactions with water and atmospheric gases.
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Denudation: Denudation refers to the processes that wear away or remove Earth's surface materials. In this context, it involves the erosion and transport of weathered basalt particles by agents like wind and water.
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Soil Formation: The weathered and transported material accumulates over time. Chemical reactions and biological activity further transform the material into black soil. The presence of minerals like iron oxide and titanium contribute to the soil's characteristic dark color. Clay minerals, particularly montmorillonite, give the soil its high moisture retention capacity.
Therefore, black soil is essentially a product of the geological history of an area, specifically regions with past volcanic activity. The type of parent rock (basalt), the climate, and time are the key factors influencing its development.
