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Soils in India

  • Soil is the uppermost layer of Earth’s crust.
  • Soil is the medium in which plants grow and thus it supports the lives on earth.
  • A number of factors contribute to the soil formation and fertility viz.

 

Parent rocks
  • The rock from which the soil is formed
  • Decomposition and disintegration of parent rock under the processes of weathering
  • The characteristics of rocks influence the characteristics of soils
  • Examples Lava rocks black soils and iron oxide rich rocks red soils
Climate
  • Influence the rate of weathering of rocks
Slope
  • The nature of relief and slope influence the accumulation of soils
  • That is why Mountains have thin soil cover but the plains have thick soil cover
Time
  • Provides maturity to the soil
  • Various forces of nature such as change in temperature, actions of running water, wind and glaciers, activities of decomposers etc. contribute to the formation of soil
  • Chemical and organic changes which take place in the soil are equally important
The soils of India on the basis of their formation are divided in the following two broad categories viz. 

  • Residual Soil Which form at the place of their origin for ex. Black soils
  • Transported Soil Which are transported from place of their formation for ex. Alluvial soils

 


Types of Soils Found in India

Alluvial Soil

  • Formed by depositional work of rivers valleys, flood plains & deltas
  • Highly fertile Riverine soils Transported type
  • Largest Tract Satluj Ganga Plains
  • Less connection with Parent material
  • Rich in Potash but deficient in Nitrogen & Humus content
  • Good for both rabi and kharif crops
  • In delta region, they are ideal for jute cultivation
  • Best for cereals & Pulses
  • Khadar Deposited by flood annually (Fresh silt) non porous, clayey and loamy
  • BhangarAbove flood level; well drained & drier coarse in nature, contain kankar (lime nodules), pebbles, gravels
  • Forms 22.16 % of the total land area of the country

Black Soil

  • Formed By solidification of Lava
  • Mainly found in Deccan Plateau
  • Also known as black cotton soil or Regur soil
  • Black colour is due to its iron content, derived from plutonic lava materials
  • Highly fertile (< Alluvial)
  • Residual type of Soil
  • Deficient in organic content, phosphorus, nitrogen
  • Rich in lime and iron, magnesia and alumina; also contains Potash
  • Highly clayey and impermeable Highly moisture retentive
  • Ploughed in dry season as on evaporation cracks develop for better seed penetration
  • Regions Maharashtra, Gujrat, Madhya Pradesh, Andhra Pradesh, Parts of Tamil Nadu
  • Forms 16.6 % of the total land area of the country

 

Red & Yellow Soil

  • Formed by weathering of Igneous (crystalline) & metamorphic rocks
  • Less fertile than Alluvial & Black soils
  • Lacks water retentive capacity
  • Reddish in color due to presence of Feo (Ferrous oxide)
  • Looks Yellow in Hydrated form
  • Transported type of soil
  • Deficient in nitrogen, lime, magnesia, humus and phosphate
  • Rich in potash and become fertile with the proper use of fertilizers and irrigation
  • Are porous, aerated & friable in nature
  • Regions Periphery areas of Deccan Plateau viz. Chhotanagpur plateau, Telangana, Nilgiris, Tamil Nadu, Karnataka, Andhra Pradesh
  • Suitable for the cultivation of millets, pulses, Linseed, tobacco etc.
  • Forms 10.6% of the total land area of the country

Soils of India

 

Laterite Soil

  • Formed under conditions of high temperature and heavy rainfall with alternate wet and dry periods
  • Thus its formation takes place strictly under monsoon conditions
  • Formed by leaching away of siliceous matter
  • With rain, Lime & Silica leaches away, leaving insoluble Feo & Al compounds Desilication
  • Humus content of soil is fast removed by bacteria which thrive well in high temp.
  • Residual type of soils, formed by leaching in areas of heavy rain
  • Mainly found in Highland or Plateaus with heavy rainfall
  • Not useful for agriculture except for plantation crops like Tea, Rubber, Coffee & Cashews
  • Used as building material & in making bricks
  • Are of Coarse texture with soft & friable nature
  • Poor in Lime, Nitrogen, Magnesium & Humus content ; Rich in Feo & Alumina
  • Regions Meghalaya, Karnataka, Kerala, Tamil Nadu, hilly regions of Assam, Rajmahal hills and Chhotanagpur plateau
  • Forms 7.2 % of the total land area of the country

 

Saline / Alkaline Soil

  • Found in arid or semi-arid conditions along with water logged areas
  • Highly saline due to dry climate, poor drainage & high evaporation
  • Infertile & does not support vegetative growth
  • Found at Bihar, Rajasthan, UP., Punjab, Haryana, Maharashtra
  • Salinity also Caused due to excessive irrigation in dry conditions which promotes capillary action

 

Arid Soil

  • Found in areas with rainfall < 50 cm
  • Sandy, porous, coarse & rich in salts
  • Generally saline due to high evaporation
  • Covered with thick brown mantle which inhibits soil growth
  • Originated from the mechanical disintegration of the ground rock of by deposition by wind
  • Low rainfall and high temperature are reasons for the formation of this soil
  • Mainly in SW Haryana & Punjab and W – Rajasthan
  • Actually fertile, water being the only limiting factor
  • Cereals grown are Jowar, Bajra, Ragi & Oil seeds Drought resistance crops
  • Forms 3.9 % of the total land area of the country

 

Mountain Soils

  • Prone to soil erosion top soil getting washed away due to the steep slopes of the mountains after a heavy rainfall
  • These soils are mostly thin and infertile
  • Include peat, meadow and forest hill soils
  • Rich in humus but deficient in potash, phosphorous and lime
  • Generally loamy & silty on valley side and coarser in upper slopes
  • Useful for Tea, coffee, spices and tropical fruits
  • Regions Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Assam, Sikkim, Arunachal Pradesh

 

Peaty / Organic Soil

  • Found in high rainfall + high humid areas of WB, Orissa & Kerala
  • Rich in Humus & organic content, Sometimes alkaline too
  • Heavy, Dark & acidic


Salinity of soils

  • Predominance of Chloride & sulfates of N, Ca & Mg, Esp. of NaCO3
  • Decreases soil fertility, Quality of fodder becomes poor, Difficulties in Housing & road construction
  • Addition of Gypsum (Converts Alkalis to compounds), Addition of rice husk & rice straw also counters alkalinity by forming light acids
  • Crop rotation involving Daincha (Green Fodder) also counters salinity

 

Soil Erosion 

  • Washing away of topmost fertile layer of the soil by the action of wind or water
  • Common causes includes:
  • Over-grazing
  • Deforestation
  • Action of wind, water, glacier, etc.
  • Topography viz. steep slopes & heavy rainfall
  • Faulty methods of agriculture, over – irrigation, shifting agriculture etc.
  • Other anthropogenic factors viz. mining, industrial activities etc. 
Effects of Soil Erosion 

  • Loss of fertile top soil
  • Lowering of the underground water table and decreasing soil moisture
  • Drying of vegetation and extension of arid lands
  • Increase in the frequency of droughts and floods
  • Silting of river and canal beds
  • Recurrence of landslides

 


Prevention of Soil Erosion Techniques

Terrace Farming

  • On hilly slopes, terraces act as bunds and prevent the soil from being washed away
  • Farming is done on a unique step like structure and the force of water running off is slowed down
  • Terraced farming is more common on small farms and in underdeveloped countries, since mechanized equipment is difficult to deploy in this setting

Terrace Farming

 

Contour ploughing

  • Land should never be ploughed up & down as it increases erosion
  • Ploughing along contours on a slope prevents soil being washed away by rainwater or by surface run off
  • Contours act like bunds and thus prevents soil erosion by allowing water to slowly penetrate the soil
  • Terraces are leveled into step like small fields with even slope

Contour ploughing

 

Contour barriers / Contour trenching 

  • Contourstrips which intercept downslope flowing water and soil particles
  • Several 2 feet by one foot trenches are formed across the slopes at suitable intervals
  • Tree seedlings are to be planted above the trench
  • Thesebarriersslow down the water movement and reduce its erosive force
  • They also filter out and trap many of the suspended soil particles, keeping them from being washed out of the field

contour barrier

Afforestation

  • Planting of trees along the edges of the fields, the waste land and on steep slopes to prevent soil erosion
  • Also to enhance the capacity of the soil to retain water

 

Shelter Belts  

  • A line of trees or shrubs planted to protect an area, especially a field of crops, from fierce weather
  • Farmers plant trees in several rows to check wind erosion
  • Also known as wind breaks

Shelter belts wind break

Cover crops / Crop rotations

  • Cover crops such as legumes, white turnip, radishes and other species are rotated with cash crops to blanket the soil year-round
  • Act asgreen manurethat replenishes nitrogen and other critical nutrients
  • Also help suppress weeds & increase soil fertility

 

No-till farming 

  • Also calledzero tillageor direct drilling
  • A way of growing crops or pasture from year to year without disturbing the soilthroughtillage
  • Increases the amount of water that infiltrates into the soil
  • Also increases organic matter retention and cycling of nutrients in the soil
  • keeps soils anchored in place rather than having bare ground exposed to wind and water

 

Strip Cropping

  • Crops are grown in alternate strips of land to check the impact of the winds
  • It is used when a slope is too steep or when there is no alternative method of preventing soil erosion.
  • Contour strip cropping → Cultivation of soil protecting crops in strips alternating with erosion permitting crops. The strips should be across the slope.
  • Field strip cropping → Plants are cultivated in parallel strips across the slopes

Strip cropping

Mulching

  • Mulchesare materials placed over the soil surface to maintain moisture and improve soil conditions
  • A protective layer of a material that is spread on top of the soil
  • Mulches can either be organic — such as grass clippings, straw, bark chips, and similar materials
  • Or inorganic — such as stones, brick chips, and plastic

mulching

 

Construction of Dams

  • Rivers causes soil erosion
  • Dams are built in the upper course of rivers to control erosion of soil
  • This would check the speed of water and thereby save soil from erosion
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3 Comments

  1. nice work

  2. awesome site , appropriate for the particular information given on this site

  3. as per diagram red soils are more area than black soils….percentage mentioned. pls mention correct percentages

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