UNIT 3 - Natural Resources LAND Resources PDF

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Natural Resources LAND Resources...

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LAND RESOURCES All types of landforms on which human being depend for their livelihood. Example: Hills, valley, plain, river basin etc. With careful utilization, land can be considered as renewable resources. Following are some important factors which affect or decide the value of land as a significant natural resource:  Soil and terrain conditions  Freshwater conditions  Climatic conditions, and  Biotic(vegetation and animal life) conditions Land in general refers to any piece or entire of the terrestrial earth but as a natural resource it means that component of the earth which is of direct economic use for the human population living on it. In fact land is one of the most important natural resources upon which we depend for our food, fibre and fuel wood, the basic amenities of life. But this resource is not infinite. There are limited land resources available for direct human use. It is the top soil or the uppermost portion of the earth crust that actually forms useful land resource. Land is classified as a renewable natural resource because it is continuously regenerated by natural process though at a very slow rate. But, when rate of erosion is faster than rate of renewal, the soil becomes a non-renewable resource. It is said that about 200-1000 years are needed for the formation of one inch of soil. As a valuable resource land is, thus, used for:   

building houses, constructing roads and railways, installing industries and developing towns and cities on it cultivating food and fodder for humans and their livestock production of raw materials for industries raising forests and other industrial woodlands damping of waste generated during domestic and industrial processes

Land use involves the management and modification of natural environment or wilderness into built environment such as settlements and semi-natural habitats such as arable fields, pastures, and managed woods. Land use planning refers to policy of using a portion of land strictly for the purpose it is suitable. Different types of land are classified into various categories. Each category is assigned a suitable type of use and it should be utilised for the purpose fixed for it. Land is being put to varied types of uses worldwide. Earlier when human population was limited major portions of land were under forests and other natural cover. But with increase in human

population and advancement in the technology, more and more land had been brought under various types of modifications. Now more land is required to be used for agricultural purposes to meet the growing needs of food production. With his economic developmental activities gaining momentum, man put land to various other uses including establishment of industrial areas, mining, transportation, urbanisation, etc. As a result:     

Agricultural lands are expanding More and more land has been brought under industrial or urban setup Forest lands, grasslands and wetlands has been cleared of their natural cover Large portions of land are rendered degraded due to overexploitation Soil is dumped with various kinds of wastes and toxic materials

Land degradation Land degradation means reduction in the quality or value of land. When land is put to extensive use or over exploitation its quality degrades. Sometimes land is put to uses which are not suitable for that piece of land. It also degrades the land. Farmland is under serious threat due to more and more intense utilisation. Every year, between 5 to 7 million hectares of land worldwide is added to the existing degraded farmland. Some factors responsible for degradation of land include:       

Dumping of harmful wastes on land Over irrigation of farmland that leads to salinisation. Pollution of land due to use of fertilizers and pesticides Unsuitable land use Soil erosion and landslides Wrong agricultural practices Deforestation

Soil Erosion Soil erosion is the most common form of land degradation. It is the removal of outer layer of soil. It is defined as the movement of soil components, especially surface-litter and top soil from one place to another. Besides causing pollution in water bodies, soil erosion badly affects soil fertility. It is the top layer of soil that contains most nutrients and if most fertile. When this layer gets eroded it results in the loss of fertility. Almost one third of the world’s cropland is affected by soil erosion. Soil erosion is a natural process but it gets accelerated due various human activities. Deforestation, mining, overgrazing, cultivation, etc enhances the rate of soil erosion.

Causes of soil erosion Various human activities like mining, deforestation, farming, overgrazing, etc are the major causes responsible for soil erosion. Due to these processes the top soil is disturbed or rendered devoid of vegetation cover. So the land is directly exposed to the action of various physical forces facilitating erosion. Overgrazing is responsible for 35% of the world’s soil erosion while 30% of the serious soil erosion has been caused by deforestation. Unsustainable methods of farming cause 28% of soil erosion. Mechanism of soil erosion There are two main agents which cause soil erosion. These are water and wind. Water erodes soil by washing its particles along with its flow. Wind also detaches and removes the soil particles and causes their movement from one place to another.  Soil erosion caused by water is of following types: Sheet erosion: when there is uniform removal of a thin layer of soil from a large surface area, it is called sheet erosion. This is usually due to run-off water. Rill erosion: When there is rainfall and rapidly running water produces finger shaped grooves or rills over the area, it is called rill erosion. Gully erosion: It is a more prominent type of soil erosion. When the rainfall is very heavy, deeper cavities or gullies are formed on the ground. Slip erosion: This occurs due to heavy rainfall on slopes of hills and mountains. Stream bank erosion: During the rainy season, when fast running streams take a turn in some other direction, they cut the soil and make caves in the banks.  Soil erosion caused by wind is of following three types: Saltation: This occurs under the influence of direct pressure of stormy wind and the soil particles of 1-1.5 mm diameter move up in vertical direction. Suspension: Here soil particles of small size suspended in the air are kicked up and taken away to distant places. Surface creep: Here larger particles (5-10 mm diameter) creep over the soil surface along with wind.

Desertification The process of expansion of deserts or desert like conditions on the earth is called desertification. It is the conversion of productive land to unproductive arid region. It results in reduction of agricultural productivity of land. Desertification is characterised by loss of vegetation cover. There are various natural causes of desertification such as climate but generally it is induced or enhanced but anthropogenic activities. Some of the human causes of desertification are:     

Deforestation Abusive agricultural practices Overgrazing Overexploitation of underground water resources Mining and quarrying...