Soil

• Soil erosion is a major issue affecting Indian agriculture, caused by factors like heavy population pressure on land, nature of rainfall, overgrazing, bad farming techniques, deforestation, and topography
• Wind erosion reduces the productive capacity of soil as nutrients required by plants are carried away by the wind
• Prevention methods for soil erosion include terrace farming, shelter belts, contour ploughing, strip cropping, planting trees, construction of dams, and plugging gullies
• Terrace farming on hilly slopes prevents soil from being washed away by running water, practiced successfully in Japan, South-East Asia, and the USA
• Shelter belts, where farmers plant trees in rows, act as windbreaks to prevent wind erosion
• Contour ploughing along contours on a slope prevents soil from being washed away by rainwater or surface runoff, common in Japan, China, and some South-East Asian countries
• Strip cropping involves growing crops in alternate strips of land to prevent soil erosion by water or wind, alternating crops like hay and wheat with corn
• Plugging gullies involves filling the gullies made in the soil with silt deposition during heavy rains
• Soil conservation aims to prevent soil loss from erosion or reduced fertility, caused by factors like wind erosion, deforestation, and poor farming techniques
• Soil erosion is the removal of the topsoil cover by water, wind, and human activities
• Sheet Erosion:

  • Occurs on gentle slopes
  • Slow removal of a thin layer of soil when vegetation is destroyed
  • Rainwater washes away the thin layer of bare soils
• Rill Erosion:

  • Forms when sheet erosion continues for long
  • Silt-laden run-off forms finger-shaped rills or grooves
  • Intermediate stage between sheet erosion and gully erosion
• Gully Erosion:

  • Deep gullies made on bare soils during heavy downpour
  • Removes nutrients and heavy load of loose soils, making the soil unproductive
  • Seen in the Chambal Valley region
• Leaching:

  • After harvesting, farmers leave soils bare
  • Nutrients in the soil are leached or percolated below the top layer
• Sea or Shore Erosion:

  • Tidal waters of the sea cause damage to the soil along the coast
  • Powerful waves break hanging cliff rocks, and the broken material is removed by retreating sea waves
  • Seen throughout the eastern and western coasts of India
• Stream Bank Erosion:

  • Streams change courses by cutting one bank and depositing silt loads on the other
  • Damage is accelerated during flash floods
  • Prevalent in flood plains of Ganga, Yamuna, and other rivers
• Wind Erosion:

  • Movement and deposition of soil particles by wind
  • Soil particles move by bouncing, rolling, or suspension
  • Most visible in suspension stage as dust storms or deposition along fence lines and roads
• Causes of Sheet, Rill, and Gully Erosion:

  • Deforestation by man in the Outer Himalayas, Western and Eastern Ghats
  • Uncontrolled grazing of domestic animals in valleys and upper slopes
• Soil types:

  • Black Soil:
  • Rich in minerals, poor in nitrogen and humus
  • Suitable for cotton, cereals, citrus fruits, and vegetables
  • Red Soil:
  • Rich in lime and magnesium, poor in phosphorus and organic matter
  • Suitable for special crops like ragi, rice, and sugarcane
• Soil types:

  • Laterite Soil:
  • Low fertility due to high acidity and low moisture retention
  • Requires manuring for crops like ragi, rice, and sugarcane
• Soil types:

  • Alluvial Soil:
  • Loamy texture, rich in minerals like potash and lime
  • Suitable for a large variety of crops like rice, wheat, sugarcane, and cotton
• Soil types:

  • Coastal Alluvium:
  • Found along coastal strips of the Peninsula
  • Suitable for crops like tapioca, cashewnuts, tea, and coffee
• Soil types:

  • Deccan Lava Tract:
  • Formed by weathering of lava rocks
  • Found in Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, Karnataka, and parts of Tamil Nadu
• Soil types:

  • Highland Areas of Peninsular Plateau:
  • Subjected to deforestation by man and heavy monsoon rains
  • Local population practices shifting cultivation
• Soil types:

  • Characteristics of Black Soil:
  • Rich in iron oxide and potash
  • Poor in lime and magnesium, acidic in nature
• Soil types:

  • Characteristics of Red Soil:
  • Deep and fertile in lowlands, thin and poor in highlands
  • Poor in nitrogen, phosphorus, and organic matter
• Soil types:

  • Characteristics of Laterite Soil:
  • Coarse and porous, red due to iron oxide
  • Poor in lime, nitrogen, and magnesium, high acidity and low moisture retention
• Bank Erosion is prevalent in regions of Ganga, Yamuna, and Fadesh, Madhya Pradesh, resulting from Stream Bank erosion
• Regur (Black) Soil:

  • Colour: black, formed from weathered lava rocks
  • Texture: fine textured and clayey (up to 50% clay content), highly retentive of water
  • Expands when wet and becomes difficult to plough, shrinks during dry season developing cracks for air circulation
• Black soil retains moisture for a long time, aiding crops, especially rain-fed ones, to sustain even during the dry season
• Red Soil:

  • Develops on old crystalline rocks under prolonged weathering by rainfall
  • Distribution: mainly on the plateau region of Peninsular India
  • Characteristics: red in colour due to iron oxide, porous, loose, aerated, pH value ranges from 6.6 to 8.0
• Laterite Soil:

  • Formed by atmospheric weathering of rocks under high rainfall and temperature with alternate wet and dry periods
  • Two types: Upland Laterites and Lowland Laterites
  • Distribution: mainly in highland areas of the Peninsular Plateau
• Bhangar, the older alluvium, is composed of lime nodules or kanker and has a clayey composition
• Khadar, the younger alluvium, is light in color and composed of newer deposits
• Bhangar is found above the flood levels, while Khadar is younger alluvium as flood waters deposit new layers every year
• Khadar soil is very fertile and ideal for intensive cultivation
• Alluvial soil in India is classified into two types based on their age, color, composition, and location: Bhangar and Khadar
• Alluvial soil is formed by sediments brought down by rivers, rich in chemical ingredients, and known as riverine soil
• Alluvial soil varies in nature from sandy loam to clay, rich in minerals like iron, magnesia, alumina, potash, and lime but poor in phosphorus, nitrogen, and organic matter
• Alluvial soil is suitable for a variety of crops like rice, wheat, sugarcane, cotton, tobacco, gram, and oilseeds