• soil – 30% of earth surface

8/14/2019 Soil 30% of Earth Surface.

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Chapter 8

SOIL


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Soil 30% of Earth surface. 60% hostile,

40% habitable Rock substratum , Soil substratum Soil formation : Chemical, Mechanical,

Biological Soil Types : loam 40% sand; 40% silt; 20%clay Soil Profile : Horizons O,A,E,B,C,R Soil Water : Infiltration, Capillary, Gravity,

Evapo-transpiration, Climate Soil Organisms : Bacteria, Algae, Fungi,

Protozoan, Worms


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Soil Types


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Soil Profile


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Soil Water


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Soil Organisms


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Soil Erosion Natural factors

Water Sheet washshifting topsoil uniformlyRilling small erosion channelsGullying large erosion channels

Wind Dry, flat soilGravity Creep

Clips lumps of soilLandslide large slips

Human factors

Deforestation, Overgrazing, Agriculture


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Soil Erosion


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Soil Erosion


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Soil Conservation Biological Stubble planting, Mulching, Cover crops, Inter cropping,

Crop rotation, Afforestation, Fencing Mechanical Contour ploughing, Strip planting, Terraces, Reduced tillage


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Soil Conservation


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Soil Class:Like biological taxonomy edaphology also has a systemof classification such as orders, suborders, groups, sub

groups, families, classes etc. There mainly 11 orders.The following are some of these:

Mollisol it is fertile dark soil found in grass lands-US, Ukraine, Russia, Mongolia, Argentina etc.

Oxisol / Ultisol it is the soil with iron and aluminumoxides in its B zone. It is found in the tropics of SouthAmerica, Africa, and Asia.

Alfisol it is the weathered forest soil. It is found intemperate biomes.

Aridosol it is dry soil found in deserts. It supports afew vegetations

Histosol- it is the soil found in marshy areas. It is richin water and or anic matter


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esert cat on:The process of denuding and degrading the oncefertile land into inhospitable barren terrain bynatural or anthropogenic activities is calleddesertification. There are three types of desertsnamely, Hyper arid, where the rain fall is less than2.5 cm annually eg. Sahara; Arid, where the rainfall

is less than 5cm/yr eg. Mexican deserts; and Semiarid, where the rainfall is below 10cm/yr eg. Aizona,Kalahari etc.Desertification characterizes mainly:

Reduced plant coverReduced top soil coverReduced soil moisture reserveThe present global rate of desertification is estimatedto be at 200,000 sq. km per year.


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Causes:Natural

1. Topography: If a land is located in themiddle of a continent away from the oceans itis most likely to become a desert. E.g. Gobi

[China], Kalahari [Africa], Arabian deserts.2. Dust storms: Periodic storms may causewind erosion by removing valuable top soil E.gGobi, Mexican deserts.3. Climatic conditions: The climate of a placewhere the rainfall is below 50cm/yr and theaverage temperature is above 30C eventually

becomes a desert.


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Anthropogenic1. Deforestation: About 1,70,000 sq.kms. of forest are disappearingannually. Population growth, expansion of agriculture etc. are responsiblefor deforestation. Denuded land will soon become a desert. E.g. Forests of Madagascar, Great Plains of North America 2. Urbanization: Land use shift from agricultural to industrial, increaseddensity of population are the reasons for urbanization. Urbanizationresults in desertification literally or in concrete jungles.3. Overgrazing: Ranching activities eliminate tall tree cover in the area.Herding in ranch lands removes vegetative cover. With increased demandfor meat and other dairy products the carrying capacity of ranch lands isexceeded resulting in desertification. E.g. Sahel of Africa, South America,Australia.4. Over irrigation: Excessive irrigation raises the level of the watertable and thus makes the soil so saturated with salts that plants cannot

grow. E.g. Imperial valley USA5. Mining: Several mining operations all over the globe remove the topcover and dump huge masses of soil creating deserts. E.g. Kudemukh inMangalore, Duck town, Tennessee.6. Nuclear activity: The land used for nuclear explosions becomes adesert because radioactivity destroys biota in the area. E.g Pokhran


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Desertification


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Desertification by drought, overgrazing & erosion


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Desertification by over irrigation & salt deposition


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Control of desertification Planting more xerophytes thatcan withstand drought conditions.

Cutting down wind erosion byplanting rows of trees around aridlands. Reduce ranching andovergrazing activities.


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Land UseLand use depends on Bioclimatic conditions:

Wet tropical oxisol/ ultisol Desert - aridosol Grassland mollisol

Mid latitude forests alfisol Wetlands histosol Flood plains inceptisol

Tundra permafrost Cropland - solum


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Public policy on soilGovernment subsidy isgiven to the farmers to

increase the production.


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Due to this subsidy there are a fewproblems also:

The tax payer has to pay more formaintaining subsidy

Subsidies harm environment becausefarmers tend to use more fertilizers andpesticides to produce more.

Farmers not willing to try crop rotationThey draw more water from theunderground


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In 1985 Conservation ReserveProgramme CRP was started.

Under this 3, 35,000 farmers were givenpossession of about 40 million acres of erodible cropland.Their duty was to prevent soil erosionand preserve the top soil.

Again in 1985 a Food Security Act- FSAwas passed by which the farmers were toimplement soil conservation programmes

and get subsidy.


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In 1988 Sustainable Agricultural

research Education SARE wasstarted to encourage sustainablefarming by:

Maintaining productive top soilGrowing food safe and wholesomeReducing the use of fertilizers and

pesticidesKeeping farms economically viable


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In 1996 Wet land Reserve Programme

WRP , was organized to encouragefarmers to preserve wet lands.Again in 1996, Federal Agricultural

Improvement Reform Act FAIR waspassed through which much of thesubsidies were reduced or revoked.

The farmers had freedom to plant whatthey wanted to.It has not been very successful


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In 2002 a farm Bill was passed in the place of FAIR. This bill increases the incentives for CRP and WRP . Two newer programmes called Wildlife Habitat Incentive Programme WHIP and Environmental Quality Incentive Programme EQIP were

established to protect wildlife and reduce pollution. In developing countries the Consultative Group on International AgriculturalResearch CGIAR is helping individual subsistence farmers by variousprogrammes. One such programme is, Farmer centered Agricultural Research

Management FARM . It is a cooperative programme among 8 Asian countrieslike China, India, Indonesia, Nepal, Phillipines, Sri Lanka, Thailand andVietnam. It mainly promotes rural sustainable agriculture with inputs from recenttechnological advancements. FARM has also established Farmer Field Schools where farmers innovatefarm practices and compete with peers. Similarly, Kenya Agricultural Research Institute KARI has established 5farmer field schools. By 2002 around 475 farmers have taken part in these schools.

Strategic Themes:


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Strategic Themes: Sustainability: Top soil is lost all over the world due to expansion of agriculture,overgrazing, deforestation, desertification etc. In normal crop lands, FARM, WRP, WHIP, SARE etc. are taking initiatives. Farmer field school is an example. Inmountainous areas, like Hindu Kush Himalayas HKH , where landslides and

erosions are common, a new programme called Three Strata Forage System TSFShas been initiated. The three strata include, 1. Grasses & Legumes, 2. Shrubs, 3. Fodder trees. This system will provide food for livestock and humans, prevent soil erosion, enrichsoil, and yield income generating products also. For example a shrub called, SeaBuckthorn [Hippophae] has the following advantages:

o It is a nitrogen fixero Its roots hold soil very wello It is a good food for cattleo Yields vitamin rich berrieso Oil from berries is medicinalo Wood can be used as fuel

Stewardship: The farmers, shepherds etc. are the tenants of the soil. Their duty is tolive and protect the soil. If they fail in their duty they will lose their abode. Example isthe, Dust Bowl tragedy of 1930. Intensive farming and overgrazing in the SouthernGreat Plains of US lead to loss of top soil. Wind and drought worsened the situationforcing thousands of people to flee their home land. Sound science: Most data on soil health are collected by aerial surveys. Some timesthese surveys may not be factual as demonstrated by the GLASOD study. So actual

round stud is im ortant to assess the extent of de radation and erosion.


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• soil – 30% of earth surface

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