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Human population & it’s effect on soil

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  • 1. SOIL , FORESTS AND WATER GROUP-4
  • 2. THE SOIL SYSTEM     Soil is a composite environment which is the result of abiotic factors (independent of human actions), such as:alterations to the bedrock (which provides soil's mineral elements), atmospheric content (oxygen fixation, nitrogen cycle, water cycle). The composite environment of soil also consists of biotic factors such as :the content of vegetation cover and the decomposition of living things. The analysis of a section of soil shows a superimposition of layers made up of different colours, different chemical compositions and different sizes of material. Each superimposition of layers creates a
  • 3. TYPES OF DEGRADATION     By 2050, the world population will have reached 9 billion. Soil has therefore become a fundamental resource that must be protected as a matter of urgency. The degradation process can take different forms: hydraulic erosion, wind erosion, changes in the soil's composition physical degradation.
  • 4. Soil provides living things with food, fibres and fuel. It supports wildlife and rural and urban activities. From late 1940s to the early1990s, over 90% of the degradation of productive land was due to overgrazing, deforestation and inappropriate agricultural practices. These changes in the soil affect over 2 billion people, most of the 852 million people suffering from hunger in particular.
  • 5.    According to the ISRIC World Soil Information data:46.4% of soil is experiencing an important decrease in productivity and partially destroyed biological functions. A third of it is in Asia and a fifth is in Africa. 15.1% of soil can no longer be used for farming as its biological functions have been seriously destroyed and it would take large investments to restore them. About 9.3 million hectares (0.5%) of soil is irreparably damaged and no longer has any
  • 6. CAUSES OF SOIL DEGRADATION    Human activity is the main cause of soil degradation. Agriculture plays a large part in soil degradation, especially clearing, irrigation, the spreading of chemical fertilisers and pesticides, overgrazing and even the passage of heavy farming equipment. Irrigation and soil drainage can cause soil acidification and salination whilst the use of chemical fertilisers and pesticides contributes to reducing soil capillarity (runoff) as well as its consistency. Overgrazing by cattle threatens the productive capacity of soils thus making them more
  • 7. IMPACT OF URBANISATION ON SOIL A large percentage of the global population reside in urban areas. Thus cities are important driving forces in environmental trends.As the world continues to urbanize, however, humans have lost contact with soil and the services it provides to sustain life. The ability of urban activities to influence the physical conditions and pollution levels in soils at a distance is increasing. Cities and urban processes have had dramatic but varying impacts on soil physical and biochemical properties and pollutant loads, all of which affect the life-supporting services of soils. As developing countries continue to industrialize, soil pollutant contamination in their cities continue to increase to levels warranting immediate action. In urban areas, pollutants such as heavy metals which are dumped can affect soils, just as old industrial sites
  • 8. CONSEQUENCES  A third of all cultivated land is losing its arable layers faster than it is gaining them and this lessens its productivity.  Using pesticides and chemical fertilisers destroys soil fauna which is necessary for aerating soil. The well-known consequence of this phenomenon is soil runoff which causes floods and mudslides.  Wind erosion which has been worsened by overgrazing and tillage in some cases, causes dust storms like in the USSR in 1960 or in Africa where 2 to 3 billion tons of soil particles leave the continent every year, thus gradually wearing away the soil's fertility.  By changing the composition and structure of soils, agriculture makes it more difficult for CO2 to be stocked in soil. Indeed, the conversion of meadows, forests and peat bogs into crops significantly reduces the amount of pedological carbon storage in soil.  As well as the loss of biodiversity (climax vegetation and environmental habitats) which comes with soil degradation and regression, there are also effects on climate change, especially through changes in the albedo on a local level and greenhouse gas emissions (soil asphyxiation).

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