Control of Soil ErosionPrepared by: Presented with:Sagun paudelHealth Assistant , • Rajendra sapkotaStudent of BPH @ lA • Rabeeta pokhrelGRANDEE internationalcollege, simalchourPokhara
IntroductionWhile protecting and improving landinvestment, controlling soil erosion will:• sustain or improve crop yields• reduce drainage costs• retain nutrients and chemicals where applied• reduce hazards when working on eroding soil, and• help improve water quality.
Management of soil for water and wind erosioncontrol is based on sensible soil conservationpractices. The majority of these practices arerecognized components of good soil, crop, andwater management. For effective erosion control:• maintain good soil structure• protect the soil surface by adequate crop and residue cover, and• use special structural erosion control practices where necessary.13/10/2012 Env health- class Presentation 3
These factors often control both water and winderosion. Not all erosion control practices will fitinto every farm management scheme.However, each erosion problem can beremedied by choosing one or more of theremedial practices appropriate to the problem.13/10/2012 Env health- class Presentation 4
METHOD OF CONTROL1. COVER methodso Mulchingo Cover crops and green manureso Green manures - also usually legumeso Mixed cropping and inter-croppingo Early plantingo Crop residueso Agroforestry13/10/2012 Env health- class Presentation 5
A permanent vegetative cover is the bestprotection for soil. The moment vegetation isdestroy the condition becomes favorable for soilerosion.Studies at Phewa Tal watershed has indicatedthat bare ground allows four times more soilerosion compared to permanent plant coveredground. In this method we try to plant such species,which are capable of holding soil strongly andcan survive in very adverse soil condition.13/10/2012 Env health- class Presentation 7
Beside this the farming system should also beconsidered. Improper cultivation leads to severesoil erosion. So land use system should beproperly implemented. The main principle ofbiological control is to prevent high speed ofwater and conserve water within the soil. Inbiological control following method can beadopted.13/10/2012 Env health- class Presentation 8
Mulching: mulching is the covering of the soilwith crop residues such as straw, maize, stalksetc. these cover protects the soil from the raindrop impact and reduces the velocity of run offand wind. It is also useful as an alternative tocover crop in dry areas where a cover crop shouldcomplete for moisture with the main crop.Cover crop: they are grown as a conservationmeasure either during off-season or as groundprotection under trees. They are grown as winterannuals and, after harvest, are ploughed to forma green manure.13/10/2012 Env health- class Presentation 9
Multiple cropping: the aim of multiple cropping isto increase the production from the land whilstproviding protection of the soil against erosion. Itincludes:• Rotation: growing different crops consequently in rotation reduces erosion as high rate of soil loss under row crop is counteracted by low rates under other crops.• Strip cropping: row crops and protection effective crops (legumes and grasses) are grown in alternate strips aligned on the contour or perpendicular to the wind. It is suitable for the slope of 30o.13/10/2012 Env health- class Presentation 10
High density cropping: it is used to try to obtainthe same effects for a monoculture that multiplecropping achieves for two or more crops.Agro forestry: Trees can be incorporated withina farming system by planting them on terraces,contour bounds and as ornamental around thehomestead. This reduces soil erosion andprovides additional needs to the farmers.13/10/2012 Env health- class Presentation 11
Shifting cultivation: an areas forest is cleared byslash and burn, and cultivated with crops for asecond year before being allowed to revert toscrub and secondary forest. This practice willmaintain soil fertility and reduce soil erosion aslong as the low ratio population to land areas ismaintained.Rotational grazing: for controlling erosion ongrasslands, rotational grazing is practiced i.e. Thestock is moved from one pasture to other, to givetime for the grass to recover. 13/10/2012 Env health- class Presentation 12
Proper forest management: though erosionunder forest cover is less, sever erosion mayresult when the hill forest area is subjected toclear felling, selection or shelter wood systemshould be adopted.Reforestation / afforestation: vegetation play themajor role in erosion control on gullies areasand landslides. So forestation programs shouldbe prioritized.13/10/2012 Env health- class Presentation 13
Soil management: it maintains and improves fertility andstructure of soils. High fertile soil results in high crop yield,good plant cover and therefore in conditions, whichminimize the affect of erosive agent nevertheless extensivesoil, management is not viable for land use other thanagriculture. It includes;• Increasing organic matter content: organic matter improves the cohesiveness, water retention capacity and structure of soil. Green manure, straw etc should be added as organic substance in agriculture lands, though tree litters maintain adequate organic content in forest soil.• Using soil stabilizers: it consists of organic by products, synthetic polymers and polyvalent salts. The former two bind the soil particles into aggregates and latter bring about flocculation of the clay particles. However soil stabilizers are expensive for general forestry use.13/10/2012 Env health- class Presentation 14
Continued covering: - Once the land is nakedthere is high possibility of soil erosion. Hence theland should be kept covered all round the year.Inter cropping: - In this method, the spacesamong the tree species are covered withagriculture crops, which help in soil and waterconservation.Mixed cropping: - In this system two or morethan two crops are raised in the same land and inthe same time. The benefit is that due todifferent kind of roots, soil is protected moreperfectly.13/10/2012 Env health- class Presentation 15
Wind breaks: - Windbreaks are usually used in plainareas where the wind moves rapidly and forcelywhich detaches soil particles causing soil erosion. Inthis method tree species of streng trunk, deeprooted and large crown are preferred which areraised around the agricultural landRotational cropping: - Raising only one speciesevery year may turn the soil infertile and may leadto erosion. So rotational cropping is necessary. Inthis system one crop is followed by next cropusually legume which makes the soil fertile.13/10/2012 Env health- class Presentation 16
Terracing: - In hilly areas, the farming should bedone only when the land is terraced properlybecause without terracing the run-off isincreased and soil is easily eroded.13/10/2012 Env health- class Presentation 17
REFERENCE: http://www.forestrynepal.org13/10/2012 Env health- class Presentation 18
THANKYOU!13/10/2012 Env health- class Presentation 19
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