These DAV Class 8 SST Notes and DAV Class 8 SST Chapter 2 Notes – Natural Resources: Land, Soil and Water hold significant importance as study material for students.
Natural Resources: Land, Soil and Water Class 8 DAV Notes
→ Our earth is called a unique planet. The four realms of the earth are lithophere (land), atmoshphere (air), hydrosphere (water) and biosphere (the living world).
→ The earth’s surface consists of both land and water.
→ The outermost solid layer of the earth is called the land. It is used for growing crops, building houses, grazing animals, etc. almost all human activities take place on land.
→ Lithosphere consists of loose surface material called soil which is a combination of organic and inorganic matter.
→ The organic component which consists of dead and decomposed parts of animals and plants is called humus.
→ Land is used for various purposes which is known as land use pattern.
→ Soil is formed as a result of the long, continued weathering process of rocks. It also contains water and air.
→ About 90% of the world’s population is inhabited in the plain areas of the alluvial soils of the tropical and sub-tropical areas.
→ It is crucial to reduce land degration and ensure the optimum use of land resources for the benefit of the present and future generations.
→ India has the highest percentage of cultivated land i.e., 57% as compared to any other country of the world.
→ The utilisation of land is determined by two factrors- physical factors (relief, soil, climatic conditions, mineral resources) and human factors (density of population and the technological and social requirements of the people).
→ As a resource, soil is of immense value to the farmers. Agriculture production is mainly dependent upon the fertility of soil. Rich and deep soil cover with a high degree of fertility favours agricultural production.
→ Animals also depend upon the soil to satisfy their basic needs, soil gives nutrients to plants.
→ Soil formation is influenced by five factors—parent rock, topography, climate, vegetation cover and time.
→ Fertile soil is essential for agriculture, but it is severly damaged by soil erosion.
→ Soil conservation is essential and therefore it should be prevented from being eroded. Various methods for soil conservation are- afforestation, plantation of shelter belts, terrace farming, check on reckless cutting of trees, etc.
→ Water is a precious resource. Water covers about 70% of the earth’s surface. About 97% of the earth’s total water is in the oceans and seas. This is saline water and not fit for human consumption. Remaining 3% is fresh water.
→ The main source of fresh water is rainfall. Most of the fresh water on the earth is found in the rivers, streams, lakes, ponds, ice caps and underground water.
→ Freshwater is in abundance at places which receive heavy rainfall, whereas availability of water is less in the areas where rainfall is low.
→ Water pollution is a serious problem nowadays. The untreated industrial waste and urban waste is dumped into rivers which makes the river water unsuitable for consumption.
→ Multipurpose River Valley projects have been developed all over the world to utilise water. They are those projects which serve many objectives at the same time, for example, generating hydro-electricity, navigation, etc.
→ Dams are very useful to us no doubt, but they cause ecological problems such as river water gets diverted, extensive forests get submerged under water, etc.
→ The conservation of water is important because its sources are limited. Rainwater harvesting should be encouraged in this regard. The demand of water for industries can be met by the recycled water.
→ Topography: detailed map of the surface features of land such as mountains, plateaus, plains, etc.
→ Soil: The thin layer of grainy substance covering the surface of the earth.
→ Humus: Dead and decomposed parts of animals and plants.
→ Land use pattern: The way in which a particular section of land is being used.
→ Soil erosion: The removal of the top layer of the soil by natural and human activities.
→ Soil conservation: It means various methods by which soil is prevented from being eroded.
→ Afforestation: The process of planting more trees and seeds on land.
→ Terrace farming: The method of farming in which broad flat steps or terraces are made on the steep slopes so that flat surfaces are available to grow crops.
→ Fresh water: Water fit for human consumption.
→ Contour ploughing: A technique of ploughing parallel to the contours of a hill slope rather than up and down the slope, so as to reduce soil erosion.
→ Rainwater harvesting: A method of saving surface runoff.
→ Shifting agriculture: Form of agriculture where an area of vegetation is cleared and cultivated for years.
→ Parent rock: Original rock which soil is formed by the process of weathering.