Black soil, also known as regur soil or black cotton soil, is a type of soil that is found in several parts of India. It is known for its high fertility and ability to retain moisture, making it suitable for agricultural purposes. However, black soil is not found in West Bengal.

Here are the reasons why black soil is not found in West Bengal:

1. Climate and precipitation: Black soil formation is influenced by the climate and precipitation patterns of an area. It is mainly formed in regions with semi-arid to sub-humid climates. West Bengal, on the other hand, has a predominantly humid climate with heavy rainfall throughout the year. The high rainfall and humidity prevent the formation of black soil.

2. Geological factors: Black soil is formed from the weathering of basaltic lava and is rich in minerals such as iron, magnesium, and aluminum. West Bengal, however, does not have a significant presence of basaltic rocks, which are necessary for the formation of black soil. The state is primarily composed of alluvial soil, which is deposited by rivers and is characterized by its fertile nature.

3. Soil characteristics: Black soil is characterized by its dark color, high clay content, and good moisture-retaining capacity. It has a high cation exchange capacity, which allows it to hold and release nutrients effectively. West Bengal, on the other hand, has soils that are predominantly alluvial in nature, with a sandy loam or silty clay texture. These soils have different characteristics and properties compared to black soil.

In conclusion, black soil is not found in West Bengal due to its climate, geological factors, and soil characteristics. The state's humid climate, lack of basaltic rocks, and predominantly alluvial soil composition contribute to the absence of black soil in West Bengal.