Soils of India and Types - 1 | Agriculture Optional Notes for UPSC PDF Download

Introduction

Soil is a combination of small rock particles and organic matter, known as humus, that forms on the Earth's surface and provides a medium for plant growth.

In India, soil classification dates back to ancient times, although it wasn't as detailed as modern classifications. In ancient times, soils were categorized based on a simple distinction: whether they were fertile or infertile.
This led to a classification of:

• Urvara (fertile)
• Usara (sterile)

In the modern era, as people gained a better understanding of various soil characteristics such as texture, color, and moisture, soil classification became more detailed. The Soil Survey of India, established in 1956, conducted extensive studies on the soils of India and their unique properties. The National Bureau of Soil Survey and Land Use Planning, an institute overseen by the Indian Council of Agriculture Research, also conducted significant research on Indian soils.

Alluvial Soil

• Coverage: Alluvial soil is distributed over a substantial portion of India's total land area, estimated to encompass about 45% of the country's entire geographical expanse.
• Geographical Distribution: Predominantly, alluvial soil is concentrated in the northern plains of India, especially in states like Uttar Pradesh, Bihar, West Bengal, Punjab, Haryana, and parts of Rajasthan. It can also be found in pockets of Gujarat, Madhya Pradesh, Maharashtra, and Tamil Nadu.
• Depth: The depth of alluvial soil can significantly vary from one region to another, ranging from a few meters to over 20 meters deep.
• Texture: The texture of alluvial soil in India exhibits regional variations. Generally, it consists of a combination of sand, silt, and clay in different proportions. The texture can range from sandy loam to clayey loam.
• Fertility: Alluvial soil is renowned for its exceptional fertility, providing a solid foundation for intensive agriculture. It contains a substantial amount of organic matter and essential nutrients such as nitrogen, phosphorus, and potassium. The high fertility of alluvial soil is a key factor contributing to the remarkable agricultural productivity in regions where it is prevalent.
• Cultivated Crops: Alluvial soil serves as a suitable medium for a wide variety of crops. In the northern plains, it sustains the growth of crops like rice, wheat, sugarcane, cotton, jute, maize, and oilseeds. In delta regions, it creates favorable conditions for cultivating rice and other water-intensive crops.
• Irrigation: The presence of alluvial soil in the fertile plains of India, coupled with an extensive network of rivers and canals, greatly facilitates irrigation. The availability of irrigation water has further enhanced agricultural output in these areas.
• Challenges: Despite its high productivity, alluvial soil faces certain challenges in specific regions. Issues like waterlogging and salinity are prevalent, particularly in areas where drainage systems are inadequate.

Black Soil

• Geographic Distribution: Black soil is primarily located in the Deccan Plateau region of India, encompassing portions of Maharashtra, Gujarat, Madhya Pradesh, Karnataka, Andhra Pradesh, and Tamil Nadu. It is particularly abundant in the states of Maharashtra and Gujarat.
• Formation: The formation of black soil results from the weathering of basaltic lava rocks, giving it a composition rich in iron, magnesium, and lime.
• Texture: Black soil is characterized by a distinctive granular texture and is renowned for its high water-holding capacity. It exhibits stickiness and malleability when moist, but it tends to develop cracks as it dries.
• Fertility: Black soil is renowned for its high fertility and is well-suited for agricultural purposes. It comprises a significant proportion of clay, organic matter, and essential nutrients such as calcium, magnesium, potassium, and phosphorus, making it conducive to the cultivation of a wide variety of crops.
• Cultivated Crops: Black soil is especially suitable for growing cotton, earning it the alternative name "black cotton soil." It is also utilized for the cultivation of crops like wheat, soybeans, millets, sorghum, tobacco, as well as certain fruits and vegetables.
• Irrigation: Black soil exhibits strong water retention capacity and slow drainage. It has the ability to retain moisture for extended periods, which proves advantageous in dry seasons. However, excessive water can lead to waterlogging and restrict root development.
• Challenges: Black soil can present challenges, including poor drainage, waterlogging, and soil erosion when not managed effectively. During dry periods, it is prone to cracking, potentially impacting crop growth.
• Extent: Black soil covers approximately 26% of India's total land area, making it one of the prominent soil types in the country.
• Fertilizer Requirements: While black soil generally possesses good nutrient-holding capacity, certain regions may necessitate additional fertilizers to maintain optimal soil fertility and sustain agricultural productivity.

Red Soil

• Composition: Red soil is a product of the weathering of ancient crystalline rocks, such as granite, gneiss, and schist. It is characterized by a high content of iron oxide, which imparts a reddish hue to the soil.
• Distribution: The primary occurrence of red soil is in the Deccan Plateau region of India, encompassing states like Tamil Nadu, Karnataka, Andhra Pradesh, Maharashtra, along with parts of Odisha and Chhattisgarh.
• Fertility: Red soil exhibits relatively lower fertility compared to alluvial soil. It is deficient in inorganic matter and essential nutrients, particularly lacking in nitrogen, phosphorus, and organic carbon. Nevertheless, with effective nutrient management and irrigation, it can support agricultural activities.
• Cultivated Crops: Red soil is suitable for the cultivation of crops like millets, pulses, cotton, groundnut, tobacco, and certain horticultural crops. It is notably well-suited for the growth of peanuts (groundnuts).
• Characteristics: Red soil possesses a coarse texture, limited water-holding capacity, and inadequate nutrient-retention capability. Due to its sandy nature, it has effective drainage.
• Extent: Red soil spans an estimated area of approximately 3.5 lakh square kilometers across India.

Yellow Soil

• Composition: Yellow soil is the result of the weathering of crystalline rocks and exhibits a yellowish or pale appearance. It contains a relatively higher proportion of iron and aluminum hydroxides.
• Distribution: Yellow soil is primarily located in the eastern and central regions of India, including parts of Odisha, Jharkhand, Chhattisgarh, Madhya Pradesh, and Telangana.
• Fertility: Yellow soil is moderately fertile and contains more nutrients compared to red soil. It boasts better moisture-retaining capacity, rendering it more conducive to agriculture.
• Cultivated Crops: Yellow soil supports the growth of crops like rice, wheat, millets, pulses, oilseeds, and vegetables. Its ability to retain moisture makes it particularly suitable for rice cultivation.
• Characteristics: Yellow soil features a finer texture compared to red soil, with commendable moisture retention. It is often employed for rain-fed agriculture.
• Extent: While the exact area covered by yellow soil in India is not readily available, it is prevalent in substantial portions of the central and eastern regions of the country.