Land is required for the functioning of organisms, population and ecosystem. Although land appears to be unlimited resource, yet its exploitation would limit the availability of their indispensable life support system.
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Land use planning became necessary due to man’s severe damage to landscape. In USA the land has been classified into eight land types according to natural ecological features such as soil, slope and natural biotic communities land type I & II comprise level areas with good agriculture soils, land types III & IV (Steeper’s slopes) requiring greater restriction if cultivated, type V and VII used for pasture, tree crops or natural state for wildlife and type VIII (Steep slope and thin soil) for recreation, fur bearers and forest products.
The main constituent of land is soil. The world soil desired from Latin “Solum means easy material in which plant grow”. Soil is defined as “the weathered (or broken particles) surface of the earth’s crust which is associated with living organisms and the products of their decomposition”.
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The process of soil formation is called as pedogenesis. The breaking of rocks into small particles is called weathering which may be physical, climatic and biological.
Soils of India
1. Red Soil:
Largest soil group of India. Peninsular India, Bundelkhand, S. Bengal, Orissa, Central India. Madhya Pradesh, E. Andhra Pradesh, Karnataka, Tamil Nadu.
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2. Black Soil:
Deccan region. Maharashtra, Malva, Madhya Pradesh, Andhra Pradesh, Gujarat, Saurastra, Bundelkhand.
3. Laterite and Lateritic Soils:
These soils do not form well defined groups.
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4. Alkaline Soil (Red Usar, Raler soils):
Salt impregnated on drier parts of India, N. Bihar, U.P., Punjab and Rajasthan.
5. Mountain and Forest Soils of the Himalayan Region:
Mountain valley soils. Siwalik, Assam to Afghanistan
The earth’s total surface is 196,400 sq. miles of whole 30% or 7230,000 sq. miles land is surface. Out of this surface area 5000000 square miles are in Antarctica 9000,000 sq. miles as deserts 11,000,000 sq. miles are mountains region. 5,000,000 sq. miles of land surface for human habitation.
We are left with approximately 47,000,000 sq. miles of land surface, at the most for the world’s human population (Southwick 1976). In Calcutta less than 20 square feet per person space is available.
Land degradation:
The area of land surface that is potentially available for agricultural use declines from year to year. The burning of forest removes particularly the entire nitrogen supply for vegetation.
Landslides:
The downwards sliding, falling, flowing of soil, rock, debris. This may occur due to fall, slides, flows and man induced.
Soil erosion: The rock fragments and soil are detached from the original site, transported and then eventually deposited at the some new locality. This may be normal (geological) or accelerated soil erosion. Water and wind is the main agent causing soil erosion. Some other agents are chemical and biological, physical, slip, streams and biotic agencies like overgrazing and deforestation.
Desertification
Seasonally dry areas with low rainfall in Earth. Desertification involves the impoverishment of vegetation and soil resources. Desertification is a global problem. Various stage of desertification can be seen in most of the world’s dry lands.
The human activity for extreme resource use and abusive land use with climate is the primary cause of desertification.
The desertification reduced biological productivity, diversity loss, loss of agriculture potential low food serenity and reduced carrying capacity for humans and livestock. This also increased drought, flooding.
The terms desertification was coined in 1949 by A. Aubreville, a French forester. In 1968 the drought in the African Sabel was observed till 1973 and resulted the death of 1, 00,000.
The United Nations (UN) convened the first International Conference of desertification (UNCOD) in 1977. In 1978 United Nations Environment Programme (UNEP) estimated that over 1.15 x 107 m (3 x 107 km2) was severely deserted. In 1984 UNEP estimated that 35% of the world’s land surface was at risk and nearby 5.2 x 107 acres production land were being reduced to near complete uselessness.
This agency actively promoted the theory that Sahara desert was expanding southward at an average of 3.7 miles per year. In response, a number of green belt schemes were implemented. 1991 UNEP estimated that 73% of the world’s range land 47% of rainfed cropland and 30% irrigated cropland was alternate moderately desertified During the 1992 UN ‘Earth Summit’ Conference on environment and development in Rio de Janeiro world leader agreed to initiate negotiation on global desertification.
The resulting convention to combat desertification (CCD) was adopted in 1994. Following ratification by 50 countries, it becomes international law at the end of 1996.