Soils

Sandy soil spreads across the largest part of Rajasthan because the Thar desert occupies the western half of the state. It is high in sand content and low in organic matter, which keeps its fertility low.

Bajra gives a good yield even in light sandy soil under low rainfall, which makes it the main kharif crop of western Rajasthan. Moth and guar are the other crops commonly sown in the same soil.

The Hadauti plateau is formed of Deccan lava, and its weathering produces black soil. This soil is deep, clayey and moisture-retentive, and within Rajasthan it is confined to the south-eastern part of the state.

Black soil holds moisture for long periods because of its high clay content, which is what cotton needs. For the same reason Kota and Jhalawar grow both cotton and soybean.

Black soil is called regur. It develops deep cracks when dry and these close again after rain, a property that earns it the name self-ploughing soil.

Alluvial soil in eastern Rajasthan is formed from silt deposited by rivers. It counts among the most fertile soils of the state and carries a good supply of potash and lime.

Alluvial soil holds both moisture and nutrients in adequate measure, which suits rabi crops. Mustard is grown extensively across the Bharatpur and Alwar belt.

Laterite soil forms in the higher-rainfall southern part of Rajasthan. Leaching enriches it in iron and aluminium and leaves it acidic in reaction.

Red-yellow soil develops from the weathering of gneiss and schist. Iron oxide gives it the red colour, and it is generally short of nitrogen and organic matter.

Brown soil spreads through the basin of the Banas and its tributaries. It is loamy in nature and short of phosphorus and organic matter, yet remains useful for cultivation.