The problem of conserving soil and moisture is also of very great importance in the extensive regions of low and uncertain rainfall, forming parts of Punjab, Madhya Pradesh, Maharashtra, Andhra Pradesh and Karnataka. These tracts are characterized by scanty, ill-distributed and highly erosive rains, undulating topography, high wind velocity and generally shallow soils. The period of heavy downpours from August to October is the period of the heaviest erosion in these regions.
Wind erosion also has been responsible for destroying the valuable top soil in many areas. Halting the march of desert in Rajasthan is one of the vital and outstanding problems facing the country today. An extreme example of sand movement from the coast is to be seen in the Saurashtra region of Gujarat where the once-flourishing ports are now covered with advancing sand-dunes.
In addition to the erosion of the cultivated fields, neglected pastures and wastelands, considerable roadside erosion also takes place owing to the defective highway engineering. Defective drainage and water-logging throw appreciable areas out of cultivation every year and indirectly increase the erosion hazards.
Extent of soil erosion. In India, there is very little area free from the hazard of soil erosion. It is estimated that out of 305.9 million hectares of reported area, 145 million hectares is in need of conservation measures.
Severe erosion occurs in the sub-humid and per-humid areas due to high rainfall and improper management of land and water.
Agricultural land in the major part of the country suffers from erosion. Apart from reducing the yields through the loss of nutrients, erosion destroys the soil resources itself every year. For example, in Maharashtra over 70 per cent of the cultivated land has been affected by erosion in varying degrees and 32 per cent of the land having been highly eroded is no longer cultivable. In the Sholapur district, nearly 17 per cent of the land of medium depth (more than 45 cm) has deteriorated into shallow soils (less than 45 cm) in 75 years from 1870 to 1945. Similarly, in Akola, Buldana and Yeotmal districts, the number of fields with less than 37.5 cm soil depth increased during the same period by 54, 16 and 8 per cent respectively. As much as 2.3 million ha is already under ravines scattered all over India. The ravines apart from ruining the soil resources for ever are a constant threat to the adjoining fertile cultivated lands.
Table 1 . Problem of conservation of land and water in India
|Particulars||Area in million hectares|
|Total Area||Soil-Conservation problem area|
|Permanent pastures and other grazing land||14.809||14|
|Land under miscellaneous tree crops and groves||4.218||1|
|Fallow lands :|
|(i) Fallow lands other than current fallows||9.168||8|
|(ii) Current fallows||11.132||7|
|Net area under cultivation||137.9||80|
|Other land uses, not available for agriculture, forest,etc.||50.188||–|
The denudation of forests and vegetation in the Shivalik Hills, the Himalayas, the Western Ghats, the Eastern Ghats and other mountain ranges of the Deccan have resulted in floods and chos (rainy season torrents) which destroy good agricultural land. For instance, the chos in the Hoshiarpur district of Punjab covered an area of 19,282 ha which increased to 32,022 ha in 1884, to 37,730 ha in 1897 and to about 60,000 ha in 1936.
In the Himalayan regions, landslides and landslips are very serious problems caused by improper land management. The recent landslide disaster in the winter of 1969 in the Darjeeling district of West Bengal is a reminder of the bad management of land resources and a portent of worse things to come.
The erosion problem along the mountain roads is assuming very serious proportions. The Border Road Organization is finding this problem so acute that a National Seminar was organized on the problems of controlling erosion and stabilizing slopes along the highways. A huge amount of money is spent every year for keeping these important lines of communication open.
Costly reservoirs constructed under the river-valley projects are being silted up at an alarming rate owing to the denudation of forest vegetation, the cultivation of steep slopes without adopting any conservation practices, landslides, torrents, etc. Morever, as the pressure on land increases there will be a tendency and a demand for opening up marginal and steep lands for cultivation. These lands will be in greater need for measure to conserve soil and water.
Owing to our present status as a developing country we are not yet faced with the problem of environmental pollution, though the pollution of soil, water and atmopsphere is round the corner as we increase the pace of our development and exploit theses resources.
Sediment load is certainly one of our greatest agricultural hazards, particularly in the case of rivers and canals. In a country, such as USA, even after 35 years of efforts, and expenditure of large sums there has been little, if any, reduction in the overall sediment load in the US streams, mainly owing to the increase in her non-agricultural activities. In India, the situation is infinitely worse, since the sediment load from agricultural lands not only continue unabated, but it is also on the increase and the sources of sediment are multiplying because of the fast rate of our developmental activities.
In fact, if erosion is permitted to continue at its present rate, it is possible that all work will be the reclamation of soil rather than the conservation and management of soil and water.