SOIL IN RAJASTHAN

SOIL IN RAJASTHAN

CLASSIFICATION AND REGIONAL DISTRIBUTION

What is Soil?

Soil refers to the layer of disintegrated rocks on the upper surface of the Earth, essential for agriculture, forestry, and supporting all life forms. It consists of minerals, organic matter, water, and air, which together make it a crucial resource for food production and ecosystem balance.

Soil Classification

1. India’s Soil Classification

India’s soil is classified into eight main types and 27 subtypes. This classification helps in determining the soil’s utility for agriculture, vegetation, and land management across various regions of the country.

2. Rajasthan’s Soil Classification

Rajasthan, with its arid and semi-arid climate, has unique soil types that vary across its different regions. The state agriculture department classifies Rajasthan’s soil into 14 types, while scientific classification follows the USDA (United States Department of Agriculture) standard, which divides soil into five major types.

Note:

• ICAR (Indian Council of Agricultural Research), established in 1929 in New Delhi, plays a critical role in soil research and classification.
• USDA (United States Department of Agriculture), founded in 1862, provides the scientific framework for soil classification, focusing on factors such as soil particle size.

3. Classification According to the State Agriculture Department

The soil in Rajasthan is divided into 14 parts according to the State Agriculture Department’s classification. These soil types are critical for agricultural planning, irrigation, and determining the types of crops that can be grown in each region.

This classification is depicted in a regional map of Rajasthan (as shown in the image), which highlights the distribution of soil types across the state.

4. Scientific Classification by USDA

The USDA classifies soil based on the size of particles, such as sand, silt, and clay, and other properties. The scientific classification for Rajasthan divides the soil into five main types:

1. Aridisol – Dry, desert-like soil, commonly found in Rajasthan’s arid zones.
2. Entisol – Recently formed soils, typically found in regions with limited weathering.
3. Alfisol – Moderately weathered soil, good for agriculture.
4. Inceptisol – Young soils, often found in hilly or mountainous regions.
5. Vertisol – Clay-rich soils that swell and shrink based on moisture content.

ANALYSIS OF SOIL TYPES IN RAJASTHAN

Classification of Soil

1. Aridisol: Aridisols are a major soil type found extensively in the arid regions of Rajasthan. They cover areas such as Bikaner, Jaisalmer, Barmer, and Jodhpur.

Key Characteristics:

• Climate: Predominantly dry, with very low moisture levels due to minimal rainfall.
• Subgroups:
  1. Camborthids
  2. Calciorithids
  3. Paliorthids
  4. Salorthids

These soils have high mineral content, especially calcium carbonate, and are typically found in desert regions. They support limited agriculture, mainly hardy crops like bajra (millet).

2. Entisol: Entisols are another dominant soil type found west of the Aravalli Range, encompassing the arid and semi-arid climate zones of Rajasthan.

Key Characteristics:

• Climate: Semi-arid, with low but sporadic rainfall.
• Extension: These soils are commonly found in desert regions like Jaisalmer, Bikaner, Barmer, and Jodhpur.
• Note: Entisols cover the largest area in Rajasthan and are among the most scientifically studied soils.

Entisols are young soils with little profile development, mainly composed of sandy and loamy textures, supporting crops such as millet and gram.

3. Alfisol: Alfisols are typically found in eastern Rajasthan and extend over regions where the climate is more favorable for moisture retention.

Key Characteristics:

• Climate: These soils are found in sub-humid to humid climates, making them more fertile than Aridisols or Entisols.
• Extension: Alfisols are predominant in eastern Rajasthan, where irrigation facilities are more common, leading to diverse crop production.

4. Inceptisol: Inceptisols are found in regions with moderate moisture availability, including areas like Rajsamand, Pali, Udaipur, Chittorgarh, Banswara, and Dungarpur.

Key Characteristics:

• Climate: Semi-arid to humid climates, which support moderate agricultural productivity.
• Extension: Inceptisols are primarily present in the southern regions of Rajasthan.

These soils are in the early stages of soil formation and are typically less developed than Alfisols but more developed than Entisols. They are suitable for mixed cropping systems.

5. Vertisol: Vertisols are found in the Hadoti region, covering areas like Kota, Bundi, Baran, and Jhalawar.

Key Characteristics:

• Climate: These soils thrive in humid and hyper-humid climates.
• Extension: Vertisols are highly productive due to their ability to retain moisture.
• Soil Type: Known for their black and chernozem characteristics, Vertisols are high in clay content, making them suitable for crops like cotton and soybeans.

Climate Conditions of Major Soil Types in Rajasthan

Study of Soils in Rajasthan on a General Basis

1. Sandy Soil

• Other Names: Commonly referred to as “dry soil” or “thirsty soil” due to its inability to retain moisture.
• Formation: Derived from the erosion of sandstone and granite.
• Regions: Found extensively in Jaisalmer, Bikaner, Barmer, and Jodhpur.
• Production: This soil supports hardy crops like Bajra (Millet), Moong, Moth, Guar, and Groundnut. The Bikaner region is particularly known for its production of gram (chickpea).
• Characteristics:
  • The soil particles are coarse, making the soil highly porous. As a result, water leakage is common, necessitating frequent irrigation.
  • Calcium content is high in these soils, making it conducive for certain types of drought-resistant crops.

Note: Sandy soil occupies the largest extension in Rajasthan, especially in desert regions. Proper irrigation techniques such as drip irrigation are essential for making these soils agriculturally viable.

2. Brown Sandy Soil

• Formation: Formed by the erosion of sandstone in the Luni Basin.
• Regions: Found in regions such as Jalore, Pali, Nagaur, Ajmer, Sikar, and Jhunjhunu.
• Note: The abundance of phosphate in this soil makes it suitable for the cultivation of certain crops.

3. Saline Soil (Reh/Kallar)

• Other Name: Saline soil is also known as “Reh” or “Kallar” due to its high salinity levels.
• Formation: Saline soils form in areas where improper irrigation causes salinity to rise to the surface, leaving a white salt layer due to the process of capillary action.
• Regions: Commonly found in areas like Barmer, Jalore, Sri Ganganagar, Hanumangarh, and Bikaner.
• Production: This soil supports the cultivation of pomegranate and sugarcane, crops that are tolerant to high salinity.

4. Alluvial Soil

• Other Name: Delta Soil.
• Formation: Alluvial soil is formed by the deposition of sediment by rivers, making it one of the most fertile soil types.
• Regions: Found in Alwar, Bharatpur, Karauli, Dholpur, Sawai Madhopur, Jaipur, and Dausa.
• Production: Crops like wheat, mustard, rye, barley, and millet are cultivated here.
• Characteristics:
  • Highly fertile due to the presence of nutrients such as potash, making it ideal for intensive agriculture.

5. Red Loamy Soil

• Formation: Formed through the erosion of metamorphic rocks, leading to its reddish color due to the presence of iron oxide.
• Regions: Predominantly found in Banswara, Dungarpur, Pratapgarh, and South Udaipur.
• Production: Crops like maize, rice, and sugarcane thrive in red loamy soils.

6. Black Soil (Cotton Soil / Volcanic Soil / Regur Soil)

• Other Name: Known as self-ploughing soil due to its capacity to retain moisture, making it suitable for crops without frequent irrigation.
• Formation: Derived from the erosion of basalt rocks, black soil is rich in clay content and has a high water-retention ability.
• Regions: Found in the Hadoti Region (Kota, Bundi, Baran, and Jhalawar).
• Production: This soil supports cotton, spices, and soybeans, making it highly suitable for agriculture.
• Note: Black soil is also known as chernozem soil, one of the most fertile soil types globally.

7. Red-Black Soil

• Regions: Found in Pratapgarh, Jhalawar, Chittorgarh, and Bhilwara.
• Production: Crops such as maize, cotton, and opium are grown in red-black soils.
• Characteristics: This soil has a high clay content and good moisture-retaining capabilities, reducing the need for frequent irrigation.

8. Red-Yellow Soil

• Formation: Formed due to the erosion of iron-rich rocks, giving it a distinct reddish-yellow color.
• Regions: Found in Udaipur, Chittor, Bhilwara, Ajmer, Tonk, and Sawai Madhopur.
• Characteristics: Rich in iron, this soil type is suitable for a variety of crops but requires proper soil management practices to prevent erosion.

SOIL PROBLEMS IN RAJASTHAN

Rajasthan faces several soil-related challenges, including desertification, salinity and water scarcity. These problems are exacerbated by the state’s arid climate, excessive irrigation, overgrazing, deforestation, and unsustainable agricultural practices leading to reduced agricultural productivity. Addressing these issues requires sustainable land management practices, proper irrigation methods, and soil conservation techniques.

The following section outlines the major soil problems in the region and the measures that can be taken to mitigate these issues.

(i) Erosion

Main Causes of Erosion:

1. Exploitation of Trees: Deforestation for timber and firewood has contributed to soil erosion by removing the tree cover that protects the soil from the impact of wind and rain.
2. Overgrazing: Rajasthan’s large livestock population exerts pressure on grazing lands, leading to the removal of vegetation cover and exposing soil to erosion.
3. Excessive Tillage of Agricultural Land: Intensive farming practices disturb the soil structure, making it more prone to wind and water erosion.

Erosion Types:

1. Layer Erosion: Occurs due to the action of air and wind, particularly in arid regions of western Rajasthan.
2. Sheet Erosion: Caused by rainwater runoff in regions such as Rajsamand.
3. Gully Erosion: Deep channels formed by river water erode the land, as seen in the Chambal Basin.

Measures to Prevent Soil Erosion:

1. Tree Plantation: Planting trees is an effective way to reduce wind erosion, as tree roots help anchor the soil and prevent its displacement.
2. Fencing of Fields: Fencing agricultural fields can reduce soil loss by preventing livestock from trampling over vulnerable areas and causing erosion.

(ii) Salinity

Causes: Salinity occurs primarily due to excessive irrigation in areas with poor drainage, leading to the accumulation of salts on the soil surface. This phenomenon is referred to as capillary action, where water rises to the surface, bringing salts with it. The excessive buildup of salts makes the soil unsuitable for most crops.

Regions Affected:

• Barmer
• Jalore
• Sri Ganganagar
• Hanumangarh

Effects:

Salinity severely reduces soil fertility, making it difficult for crops to absorb water and nutrients. The crops that can tolerate saline soils, such as pomegranates and sugarcane, are typically grown in these regions.

Measures to Reduce Salinity:

1. Leaching: This method involves flushing the soil with large quantities of water to wash away the excess salts.
2. Use of Gypsum Fertilizers: Gypsum (calcium sulfate) can be added to saline soils to improve their structure and remove sodium ions, thereby reducing salinity.

(iii) Water Logging

Definition: Waterlogging is the saturation of soil with water, causing oxygen deficiency in the root zone, which hinders plant growth and leads to crop failure.

Regions Affected:

• Hanumangarh
• Badopal
• Sri Ganganagar

Effects: Waterlogged soils can lead to root rot in crops and severely affect agricultural productivity. These areas become unworkable for many crops due to the excessive moisture content.

Measures to Prevent Waterlogging:

1. Eucalyptus Planting: Eucalyptus trees are known for their high water consumption and can help in draining waterlogged areas.
2. Sprinkler and Drip Irrigation Systems: These irrigation techniques help control the amount of water used in agriculture, preventing excess water from accumulating in the soil.

(iv) Alkalinity

Definition: When the pH of soil exceeds 8, it becomes alkaline. Alkaline soils are characterized by a high presence of sodium, calcium, and magnesium salts, which make the soil less fertile.

Effects: Alkaline soils impede the availability of nutrients to plants, affecting crop yield. Many crops struggle to grow in highly alkaline conditions.

Measures to Control Alkalinity:

1. Sowing of Guar-Drenche Crop: Crops like guar, which are resistant to alkaline conditions, are planted, and then mixed into the soil to improve its organic content.
2. Use of Gypsum and Rock-Phosphate Fertilizers: These fertilizers help reduce soil alkalinity by replacing excess sodium ions with calcium ions, improving the soil’s structure and fertility.

(v) Soil Degradation

Definition: Soil degradation refers to the physical, chemical, and biological decline in soil quality due to various factors such as erosion, excessive chemical fertilizer use, deforestation, and over-cultivation. This leads to a reduction in the soil’s capacity to support life and agricultural productivity.

Causes:

1. Excessive use of chemical fertilizers: The overuse of chemical inputs reduces the organic matter in the soil, leading to poor soil structure and fertility loss.
2. Monoculture practices: Continuous cultivation of the same crops year after year depletes the soil’s nutrients, leading to degradation.

Measures to Prevent Soil Degradation:

1. Use of Organic Fertilizers: Organic matter like compost and manure should be added to the soil to improve its structure and restore nutrient levels.

Crop Rotation: Changing the type of crops grown in each season helps prevent the depletion of specific nutrients, maintaining soil fertility over time.