The soil and vegetation of the state of Rajasthan varies with its wide-ranging topography of arid plains or parched regions, hilly tracts of the Aravalis, the flood prone plains of Eastern Rajasthan and the oldest range of fold mountains- Aravali Hills.
The ground water level is very low due to over-exploitation and the limited, erratic rainfall averaging 360mm per year allows the growth of scanty, shrub -like thorny vegetation. Grasses and species like P. cineraria grow in the regions where little water is available. Water level is available only at a depth of 30 to 61m. However food crops are grown in the plains that are drained by the rivers and streamlets owing to the alluvial and clay soil deposits. The hilly tracts of the Aravali are characterized by the black, lava soils that sustain the growth of cotton and sugarcane.
The types of soil available in Rajasthan are mostly sandy, saline, alkaline and chalky (calcareous). Clay, loamy, black lava soil and nitrogenous soils are also found.
The following are the Soil and Vegetation belts in Rajasthan that are classified owing to the topographical divisions of the state-
Western Desert Regions
The districts of Jaisalmer, Bikaner, Barmer, Jalor, Jodhpur, Ganganagar, Sirohi, Jhunjhunu, Pali and Sikar have alkaline and saline soils with a calcareous base. There is some nitrate concentration in the soil of these regions. The Jaisalmer region has Aeolian sand that varies from sandy to sandy loam. In fact Jaisalmer is renowned for its sandstone. Due to lack of water availability vegetation comprises of only thorny bush and cactuses. There is only seasonal vegetation such as a few grass species, shrubs and dwarf trees.
Irrigated North western plain
The whole district of Ganganagar consists of alluvial and Aeolian soil as it is flooded by the Ghaggar River. The Gang Canal and Bhakhra Canal enables the flow of water and hence this area is filled with lush vegetation and food crops consisting of maize, guar, sesamum, wheat, mustard, gram, fruits and so on.
Semi - Arid Eastern Plains
The four districts of Dausa, Tonk, Jaipur and Ajmer are watered by river Banas and its tributaries and thus the fertile soil sustains mixed xerophytic and mesophytic vegetation. Cultivation crops like barley, gram, wheat, mustard are grown in the rabi season.
Flood Prone Eastern Plains
The flood plains of Rajasthan consist of the districts of Bharatpur, Alwar and Dhaulpur and the northern region of Sawai Madhopur which are flooded by the river Ghambhiri and Banganga. Thus this region is the repository of alluvial, clay and loamy soil.
The Aravali Hills & Sub-humid Southern Plains
The Bhilwara district and the major parts of Udaipur district, Chittaurgarh district, Sirohi district and the tract of Aravali Hills forms a part of inter-mountain plateau an consists of dark- lava soils. Major cash crops like cotton and sugarcane are grown in this black soil region. Other food crops are also grown.
Humid South-Eastern Plains
The Hadauti plateau includes the districts of Baran, Bundi, Jhalawar and Kota and so on that have black soil. This region is fertile owing to the presence of the Chambal River and its distributaries and cotton,sugarcane and opium are grown.
Some districts of Rajasthan such as Dungarpur, Banswara, Udaipur, Bhilwara and Chittaurgarh have red and yellowish soils.
Last Updated on : 01 December 2011