Soils PDF

## Soils * Soil is a mixture of rock debris and organic materials which develop on earth's surface. * Climate * Vegetation * Relief * Other life forms * Parental material * Time * Factors affecting formation of soil. * Horizons: Soil consists in layers and each layer is call...

## Soils * Soil is a mixture of rock debris and organic materials which develop on earth's surface. * Climate * Vegetation * Relief * Other life forms * Parental material * Time * Factors affecting formation of soil. * Horizons: Soil consists in layers and each layer is called Horizons. * There are 3 horizons: * Horizon A: Toppest zone, where organic materials have got incorporated with the mineral matter. * Horizon B: Transition b/w horizon A and B. It has some organic material in it. * Horizon C: Is composed of loose parent material. * Underneath, these three horizons, is a rock called Parent Rock or Bedrock. * This arrangement of soil is called Soil Profile. ## Classification of Soils * In ancient times, soils used to be classified into two main groups: Uruara and Usara. * Based on texture, soil can be classified into: Sandy, clayey, silty and loam. * Based on colour, soil can be classified into: Red, yellow, Black etc. * On the basis of genesis, colour, composition, and location. * The soils of India can be classified into: * Alluvial Soil * Black Soil * Red & Yellow Soil * Laterite Soil * Arid Soil * Saline Soil * Peaty Soil * Forest Soil ### Alluvial Soils * Widespread in Northern part. * Covers 40% of total area of India. * Alluvial soils can be divided into two types: * Khadar (New Alluvium) * Bhangar (Old Alluvium) ### Black Soil * Covers most of Deccan Plateau. * Also known as 'Regur Soil' or 'Black Cotton Soil'. * Clayey, deep and impermeable. * Rich in lime, Iron, Magnesia, and Alumina. * It lacks in Phosphorus, nitrogen, and Organic matter. ### Red & Yellow Soils * Develops on Crystalline igneous rocks. * Found in parts of Odisha and Chhattisgarh. * Develops in reddish colour due diffusion of Iron in it. * Look yellow in hydrated form. * Poor in nitrogen, phosphorus, and humus. ### Laterite Soil * Laterite word has been derived from Latin word meaning Brick. * Develops in the area with high temperature and high rainfall. * Rich in iron oxide and Aluminium content. * Poor in organic matter, nitrogen, phosphate, and Calcium. * Suitable for growing Cashewnut. * Laterite soils are found in Karnataka, Kerala, Tamil Nadu, MP, and hilly areas of Odisha & Assam. ### Arid Soils. * Range from Red to brown in colour. * Sandy in structure & Saline in nature. * Lack moisture and Humus. * Nitrogen is insufficient, and phosphate is normal. * Found in Western Rajasthan. * Lower horizons are occupied with "Kankar". ### Saline Soils. * They are known as "Usara Soils". * Contain larger proportion of Sodium, Potassium, and magnesium. * Lack in nitrogen & Calcium. * Widespread in western Gujarat, deltas of eastern coast and in Sunderban areas of WB. * In the areas of intensive cultivation with excessive use of irrigation, especially in areas of Green Revolution. * The fertile alluvial soils are becoming saline, then farmers are advised to add Gypsum to solve salinity problem. ### Peaty Soils * Found in areas of heavy rainfall and high humidity. * 40%-50% Organic matter, in the soil. * Nearly and Black in colour. * Occurs in Northern Bihar, Southern Uttarakhand, and TN, Odisha, and WB. ### Forest Soils * Found in forest areas. * Vary in structure and texture depending on the environment they formed. * Loamy and silty in valley sides and coarse grained in upper slopes. * Lower valley soils are fertile. ## Soil Degradation * The decline in soil fertility when the nutritional status declines, and depth of soil goes down due to erosion and misuse is called Soil Degradation. ## Soil Erosion * The destruction of soil cover is called Soil Erosion. * Soil forming processes and erosional processes go on simultaneously. * The rate of removal of fine particles, and addition of particles to soil layer is the same. * Sometimes, such a balance is disturbed by natural or human factors leading to a greater removal of soil. ### Agents of Soil Erosion. * Wind * Water * Deforestation ### Factors of Soil Erosion. * Overgrazing * Over Irrigation * Shifting Cultivation. * A region with a large number of deep gullies, or ravines are called Badland Topography. ## Soil Conservation * Soil conservation is a methodology, to maintain soil fertility, prevent soil erosion and exhaustion, and improve the degraded condition of soil. ### Remedies to Control Soil Erosion. * Countour Ploughing * Countour Terracing * Regulated Forestry * Controlled Grazing * Cover Cropping * Mixed Farming * Crop Rotation * Finger gullies can be reduced by Terracing. * Bigger gullies can be reduced by Check dams. * In semi-arid and arid areas, efforts should be made to protect lands from encroachment of sand dunes by developing shelter belts of trees.