Soil conservation includes all such measures which protect the soil from erosion and restore its fertility. These measures are of two types-(a) small measures to check soil erosion at local or even individual level, and (b) large measures at government level involving larger area and heavy investment.
(a) Small Measures-These include afforestation, regularised land strip cultivation or contour farming or terrace farming in hilly areas, use of stubble mulch system, increasing cohesiveness of the soils through artificial manures and fertilisers, gully plugging, restricting over grazing and shifting cultivation, erecting shelter belts and wind breaks to check wind velocity and wind erosion in arid and semi-arid areas, Fixing of sand dunes by planting trees and grasses, practicing alternate cultivation technique, popularising dry farming and adopting scientific crop rotation system.
(b) Large Measures-these include large projects and schemes undertaken by state and central government to check soil erosion and facilitate extensive reclamation. Following are some of the schemes worthy of mention here:
(i) Reclamation of Ravines and Badlands-
Massive large scale schemes are necessary for soil reclamation in ravines and badlands of Madhya Pradesh, Uttar Pradesh, Gujarat and Rajasthan. Several such schemes involving plugging of gully mouths, construction of bunds across the gullies, leveling of surface, a forestation, and restriction on over grazing are under implementation in these states. In Madhya Pradesh the World Bank has given an assistance of Rs. 300 million to reclaim about 1 lakh ha of ravine land.
(ii) Control of Floods-In India the problem of soil erosion is very much linked with the problem of floods and waterlogging. This is due to seasonal and heavy downpour of rainfall. If arrangement could be made for the storage and diversion of additional rain-water not only it would be an effective measure to control the floods but to utilise this water in drier yet to see the light of the day due to paucity of funds.
(iii) Afforestation-Afforestation is another effective measure to check the erosion of soil either through running water or through winds. Such trees can be planted along the roads, canals, river banks, bordering areas of the desert and in ravine and wasteland areas. A forestation programmes may be undertaken at local and community level and also on regional and national level.
Along with a forestation equally important is the restriction on the indiscriminate cutting of trees. People's awareness in the form of Chipko movement and use of cheap substitute for fuel wood and wood products may be effective steps in this direction.
(iv) Restoration of Long Fallows-the country has 95.5 lakh ha. of old fallows of which about 80 ( lakh ha lie in 8 states, namely, Andhra Pradesh, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan, Tamil Nadu, Bihar and Uttar Pradesh.
In 1982-83 a programme for restoration of long fallows was j launched in these 8 states which was later on extended to 5 more states (Assam, Gujarat, Meghalaya, Orissa and West Bengal). On the basis of progress, reports about 9.66 lakh ha of fallows in these states were restored for productive purposes.
(v) Shifting Cultivation-a scheme to control shifting cultivation has been launched in seven northeastern states of the country. This is a beneficiary oriented programme which aims at rehabilitating Jhumia tribal families with one hectare of terraced agricultural land and one hectare of horticulture and plantation crops.
The 8th Five Year Plan had an outlay of Rs 45 crore for the purpose. There is a need to extend this programme to other states of the country and gradually replace this old system by sedentary farming.
(vi) Reclamation of Alkaline (Usar) Soils- This is a centrally sponsored scheme launched in the states of Haryana, Punjab and Uttar Pradesh during the Seventh Five Year Pan. It has now been extended to the states of Gujarat, Madhya Pradesh and Rajasthan. The major components of the scheme include assured irrigation water, on farm development works like land leveling, deep sloughing, community drainage system, application of soil amendments, organic manures, etc. It is a 50: 50 funding between the Centre and the concerned states on identified components. Since the inception of the scheme an area of 4.32 lakh ha. Has been reclaimed with central assistance of Rs. 59.67 crore up to 1995- 96. There is a need to launch this scheme in other states of the country to combat the problems of salinity and alkalinity.
Soil Conservation through the Plans
Soil conservation programmes are taken in the context of national plan strategy to make the country self-reliant in food and other land based produces as well as to generate additional employment opportunities in the extensive rural areas.
The characteristic features of the programmes include : (a) implementing field measures such as terracing, contour farming, intercropping, etc., for controlling run off and erosion, (b) raising wind breaks, shelter belts to check wind erosion, protecting crops from hot fast wind and fixing sand dunes, (c) land development and shaping, (d) a forestation and raising of utility trees, and (e) putting up erosion control-cum- water harvesting structures with a view to restoring degraded lands, create micro-level irrigation potential and closures with working of soil conservation measures for development of grass-land (India 1985, p. 289).
The Central Government formed a Central Soil Conservation Board in 1953 to co-ordinate soil conservation programmes on all-India basis.
The Board implemented soil conservation programmes over 2.5 lakh hectares of area during the First Five Year Plan which increased to 8 lakh hectares during the Second Plan and 44 lakh hectares during the Third Plan. During Fourth Plan soil conservation programmes were redesigned to be implemented on watershed basis and 21 catchments covering 71 lakh hectares of area were selected. Fifth Plan had an allocation of Rs. 161 crores to reclaim 10 lakh hectares of area in catchment of major rivers and ravine lands as a result of which the total area treated under soil conservation programmes rose to 23.4 million hectares.Sixth Plan aimed at bringing additional 7.1 million hectares of area under soil conservation programmes.
It also included centrally sponsored scheme of integrated water-shed management in the catchments of 8 flood prone rivers of the Ganga basin. The Seventh Plan fixed a total outlay of Rs. 740.39 crore to put emphasis on preventing soil erosion and increasing soil productivity. Till 1995- 96 a total area of 39.3 million hectares in the catch- 212 of River Valley Prjccts has been treated under soil conservation programmes. One centre has been set up at Hazaribag under D.V.C. to impart training for soil conservation schemes.
The World Bank assisted projects, namely Himalayan watershed management project in Uttar Pradesh and pilot project for watershed development in the rainfed areas in Andhra Pradesh, Karnataka, Madhya Pradesh and Maharashtra are being monitored through Watershed Development Council (WDC) in the Department of Agriculture and Co-operation.
The All-India Soil and Land Use Survey Organisation has carried out works of delineation and codification of catchments into watersheds, fixation of inter-set priorities of watersheds, determination of hydrologic soil groups, infiltration characteristics, potential and problems of various identified soil series etc.
It is busy in carrying out reconnaissance, sample and detailed soil surveys of different parts of the country and has also identified 3772 watersheds for immediate planning. States have been asked to set up State Land Use Boards for formulating, implementing and co-coordinating soil conservation programmes. A two-tier body, namely, the National Land Resources Conservation and Development Commission and the National Land Board has been set up to co-ordinate and oversee the activities of all the State Land Use Boards.
Besides Soil Conservation training Centre of Hazaribag (DVC), eight regional research-cum demonstration centres have been established at Dehradun (Himalayan region), Chandigarh (Siwalik region), Kota (ravines of Rajasthan), Valsad (ravines of Gujarat), Agra (ravines of Yamuna), Bellary (black soil), Ootacamund (hilly areas), Chhatra (watershed of Losi) and Jodhpur (desert for the study of problems of soil and water conservation.
Soil conservation is the preventing of soil loss from erosion or reduced fertility caused by over usage, acidification, salinization or other chemical soil contamination.
Slash-and-burn and other unsustainable methods of subsistence farming are practiced in some lesser developed areas. A sequel to the deforestation is typically large scale erosion, loss of soil nutrients and sometimes total desertification. Techniques for improved soil conservation include crop rotation, cover crops, conservation tillage and planted windbreaks and affect both erosion and fertility. When plants, especially trees, die, they decay and become part of the soil. Code 330 defines standard methods recommended by the U.S. Natural Resources Conservation Service. Farmers have practiced soil conservation for millennia. In Europe, policies such as the Common Agricultural Policy are targeting the application of best management practices such as reduced tillage, winter cover crops, plant residues and grass margins in order to better address the soil conservation.Political and economic action is further required to solve the erosion problem. A simple governance hurdle concerns how we name and value the land and what we call it and this can be changed by cultural adaptation.
Contour ploughing orients crop furrows following the contour lines of the farmed area. Furrows move left and right to maintain a constant altitude, which reduces runoff. Contour plowing was practiced by the ancient Phoenicians, and is effective for slopes between two and ten percent. Contour plowing can increase crop yields from 10 to 50 percent, partially as a result of greater soil retention.
Terracing is the practice of creating nearly level areas in a hillside area. The terraces form a series of steps, each at a higher level than the previous. Terraces are protected from erosion by other soil barriers.
Terraced farming is more common on small farms and in underdeveloped countries, since mechanized equipment is difficult to deploy in this setting. It protects the soil from its erosion. It is one of the way by which soil erosion can be stopped.
Keyline design is an enhancement of contour farming, where the total watershed properties are taken into account in forming the contour lines.
Perimeter runoff control
Tree, shrubs and ground-cover are effective perimeter treatment for soil erosion prevention, by impeding surface flows. A special form of this perimeter or inter-row treatment is the use of a “grass way” that both channels and dissipates runoff through surface friction, impeding surface runoff and encouraging infiltration of the slowed surface water.
Windbreaks are sufficiently dense rows of trees at the windward exposure of an agricultural field subject to winderosion.Evergreenspecies provide year-round protection; however, as long as foliage is present in the seasons of bare soil surfaces, the effect of deciduous trees may be adequate.
Cover crops/crop rotation
Cover crops such as legumes, white turnip, radishes and other species are rotated with cash crops to blanket the soil year-round and act as green manure that replenishes nitrogen and other critical nutrients. Cover crops also help suppress weeds.
Soil-conservation farming involves no-till farming, “green manures” and other soil-enhancing practices. Such farming methods attempt to mimic the biology of barren lands. They can revive damaged soil, minimize erosion, encourage plant growth, eliminate the use of nitrogen fertilizer or fungicide, produce above-average yields and protect crops during droughts or flooding. The result is less labor and lower costs that increase farmers’ profits. No-till farming and cover crops act as sinks for nitrogen and other nutrients. This increases the amount of soil organic matter.
Repeated plowing/tilling degrades soil, killing its beneficial fungi and earthworms. Once damaged, soil may take multiple seasons to fully recover, even in optimal circumstances.
Critics argue that no-till and related methods are impractical and too expensive for many growers, partly because it requires new equipment. They cite advantages for conventional tilling depending on the geography, crops and soil conditions. Some farmers claimed that no-till complicates weed control, delays planting and that post-harvest residues, especially for corn, are hard to manage.
Main article: Soil salinity control
Salinity in soil is caused by irrigating with salty water. Water then evaporates from the soil leaving the salt behind. Salt breaks down the soil structure, causing infertility and reduced growth.
The ions responsible for salination are: sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+) and chlorine (Cl-). Salinity is estimated to affect about one third of the earth’s arable land. Soil salinity adversely affects crop metabolism and erosion usually follows.
Salinity occurs on drylands from overirrigation and in areas with shallow saline water tables. Over-irrigation deposits salts in upper soil layers as a byproduct of soil infiltration; irrigation merely increases the rate of salt deposition. The best-known case of shallow saline water table capillary action occurred in Egypt after the 1970 construction of the Aswan Dam. The change in the groundwater level led to high salt concentrations in the water table. The continuous high level of the water table led to soil salination.
Use of humic acids may prevent excess salination, especially given excessive irrigation. Humic acids can fix both anions and cations and eliminate them from root zones. Planting species that can tolerate saline conditions to produce surface cover can preserve soil salinity can be reduced. Salt-tolerant plants include saltbush, a plant found in much of North America and in the Mediterranean regions of Europe.
When worms excrete egesta in the form of casts, a balanced selection of minerals and plant nutrients is made into a form accessible for root uptake. Earthworm casts are five times richer in available nitrogen, seven times richer in available phosphates and eleven times richer in available potash than the surrounding upper 150 millimetres (5.9 in) of soil. The weight of casts produced may be greater than 4.5 kg per worm per year. By burrowing, the earthworm improves soil porosity, creating channels that enhance the processes of aeration and drainage.
Other important soil organisms include nematodes, mycorrizha and bacteria.
Degraded soil requires synthetic fertilizer to produce high yields. Lacking structure increases erosion and carries nitrogen and other pollutants into rivers and streams.
Each one percent increase in soil organic matter helps soil hold 20,000 gallons more water per acre.
To allow plants full realization of their phytonutrient potential, active mineralization of the soil is sometimes undertaken. This can involve adding crushed rock or chemical soil supplements. In either case the purpose is to combatmineral depletion. A broad range of minerals can be used, including common substances such as phosphorus and more exotic substances such as zinc and selenium. Extensive research examines the phase transitions of minerals in soil with aqueous contact.
Flooding can bring significant sediments to an alluvial plain. While this effect may not be desirable if floods endanger life or if the sediment originates from productive land, this process of addition to a floodplain is a natural process that can rejuvenate soil chemistry through mineralization.
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