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| Edaphic Resources (Soil Resources) |
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| Edaphic resources refer to soil resources. Due to varying temperature, rainfall, topographical characters in different parts of world, the rocks weather differently. Further, the rocks themselves are of varying chemical composition. Due to this varying types of soils are formed. |
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| Soils are the basis of biosphere, because soils nourish and support plant growth (primary producers) and all the animals depend directly on plants as primary consumers or as secondary consumers. Soils are most important natural resource of world, for agricultural production, forest wealth. |
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| Different types of soils like alluvial soil, coastal soil, sandy soil, sand clay soil, clay loam soil, clayey soil, laterite soil, peat soil, forest soil, glacial soil are found in different parts of the globe. |
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| Natural restoration of soil fertility |
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| Nature restores soil fertility through the following processes: |
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| 1) Weathering of rocks. |
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| 2) Earthworms and rodents help bring fresh subsoil to the surface by burrowing. |
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| 3) Release of minerals by decay of faller leaves, twigs and dead bodies of animals and plants. |
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| 4) Biological fixation of nitrogen. |
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| 5) Rain brings down nitrogen compounds formed in air. |
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| Conservation of soil |
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| Preservation of topsoil is the most important step in soil conservation. This is achieved by 2 ways. They are: |
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| i) Restoration of fertility |
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| ii) Prevention of erosion. |
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| Restoration of fertility |
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| The fertility of the topsoil can be restored by taking the following measures. |
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| a) Regular use of manures and fertilizers can replenish the minerals used by the crops. Green manuring can also be done. |
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| b) Crop rotation should be practiced |
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| c) New techniques of applying water beneath the soil is being developed to prevent salinization of soil and depletion and to conserve water. |
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| d) Nitrogen fixing organisms can be inoculated into the soil. |
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| e) The practice of leaving the land fallow should be practiced. |
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| Prevention of erosion |
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| Erosion of soil can be due to action of water or air. |
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| Erosion of soil by water can be prevented by |
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| a) Checking of overgrazing and stopping the cutting down of forests. |
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| b) Terracing of sloping lands reduces the speed of water and prevents soil erosion. |
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| c) Bunds around the fields checks the erosion of the soil. |
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| d) Irrigation channels around the fields should be designed to carry water at a slow speed and fast flowing water tends to carry away the topsoil. |
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| e) Intensive cropping prevents soil erosion. |
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| f) Contour ploughing checks soil erosion by water. |
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| g) Drainage canals prevent soil erosion. |
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| Erosion of soil by wind can be prevented by having tree belts around fields which act as wind breakers. Planting of grass also prevents erosion |
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| Tree belts and grass beds check the advancement of deserts towards the fertile land. |
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| The richness in our edaphic resources is testified in Gangetic belt - which has been seat of human civilization for the past 5000 years. It is one of the few places where earliest human settlement was recorded. |
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| Our country is bestowed with some of the best soil resources. However, the types of soil, and their fertility vary widely across the country. |
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| The broad distribution of soils in our country is as follows. |
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| Alluvial Soils |
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| Mainly distributed in Gangetic plains, north eastern states, West Bengal, U.P, Orissa, parts of TamilNadu, Kerala, Gujarat, Punjab and Haryana. |
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| Alluvial soils can be a deltaic alluvium (these soils are due to transported silt across the rivers. They are mainly found in river basins or calcareous alluvium or coastal alluvium (in coasts). |
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| Black Soil |
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| Mainly distributed in Maharastra, Madhya Pradesh, parts of Gujarat, Andhra, Tamil Nadu and Karnataka. |
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| They are the products of weathering of deccan trap. They can be deep black soils, clay loam soils, sandy clay soils. |
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| Red Soils |
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| Mainly distributed in TamilNadu, South Karnataka, Goa, SE Maharastra, Eastern Andhra, parts of Orissa. |
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| They are porous soils. They can be red sandy, red loamy, red clayey type of soils. |
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| Laterite Soils |
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| They are mainly distributed in Kerala, hilly region of Karnataka, Madhya Pradesh, Orissa, and Maharastra. |
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| They are gravelly smooth and highly porous in characters. |
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| Desert Soils |
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| They are mainly distributed in Rajastan, parts of Gujarat, Punjab and Haryana. |
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| Problem Soils |
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| They are spread over in most states. They can be acid soils (where pH is in the range of 3.5 to 6.5) found in coastal and hilly tracts or highly leached region or saline /alkali soils (where pH is 7.5 to 9.5) found in any clay rich poor drained soils especially with high sodium salts. |
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| Out of these, the fertility of black soils, alluvial soils is medium to high but black soils suffer poor drainage. Red and laterite soils are well drained but poor in fertility. Desert soils are poor in fertility. Problematic soils suffer due to drainage, fertility as well as pH related issues. |
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| In a broad sense, the rich source of agricultural production is found in alluvial soil regions (especially deltaic alluvial soils) as well as black soil regions - for rainfed situations. Red, laterite soils as well as alluvial soils are suitable for irrigation. |
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| The edaphic resources are put to maximum use in our country. Due to enormous population pressure, the lands are put to maximum utility in order to achieve higher agricultural production. |
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| Out of 142 million hectares of land, nearly 43 million hectares of land is put to use more rigorously to grow two crops in a year. Remaining land can also be used to grow more crops. But, adverse rainfall distribution will not permit crops two crops in all the area. |
| |
| Natural restoration of soil fertility |
| |
| Nature restores soil fertility through the following processes: |
| |
| 1) Weathering of rocks. |
| |
| 2) Earthworms and rodents help bring fresh subsoil to the surface by burrowing. |
| |
| 3) Release of minerals by decay of faller leaves, twigs and dead bodies of animals and plants. |
| |
| 4) Biological fixation of nitrogen. |
| |
| 5) Rain brings down nitrogen compounds formed in air. |
| |
| Conservation of soil |
| |
| Preservation of topsoil is the most important step in soil conservation. This is achieved by 2 ways. They are: |
| |
| 1) Restoration of fertility |
| |
| 2) Prevention of erosion. |
| |
| Restoration of fertility |
| |
| The fertility of the topsoil can be restored by taking the following measures. |
| |
| a) Regular use of manures and fertilizers can replenish the minerals used by the crops. Green manuring can also be done. |
| |
| b) Crop rotation should be practiced |
| |
| c) New techniques of applying water beneath the soil is being developed to prevent salinization of soil and depletion and to conserve water. |
| |
| d) Nitrogen fixing organisms can be inoculated into the soil. |
| |
| e) The practice of leaving the land fallow should be practiced. |
| |
| Prevention of erosion |
| |
| Erosion of soil can be due to action of water or air. |
| |
| Erosion of soil by water can be prevented by |
| |
| i) Checking of overgrazing and stopping the cutting down of forests. |
| |
| ii) Terracing of sloping lands reduces the speed of water and prevents soil erosion. |
| |
| iii) Bunds around the fields checks the erosion of the soil. |
| |
| iv) Irrigation channels around the fields should be designed to carry water at a slow speed and fast flowing water tends to carry away the topsoil. |
| |
| v) Intensive cropping prevents soil erosion. |
| |
| vi) Contour ploughing checks soil erosion by water. |
| |
| vii) Drainage canals prevent soil erosion. |
| |
| Erosion of soil by wind can be prevented by having tree belts around fields which act as wind breakers. Planting of grass also prevents erosion |
| |
| Tree belts and grass beds check the advancement of deserts towards the fertile land. |
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