Presentation 5


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Presentation 5

  1. 1. An estimated 60% of cultivated land suffers from soil erosion , water logging and salinity. It is also estimated that between 4.7 and 12 billion tons of topsoil are lost due to annually from soil erosion. From 1947 to 2002 average annual per capita water availability declined by almost 70%. Over exploitation of ground water is problematic in states of Haryana , Punjab and UP. The Indian Agricultural Research Institute has estimated that a 3ᵒ C rise will result in 1520% loss in annual wheat yeilds. Forest covers an area of 18.34% of Indian geographic area. The Forest cover is declining because of harvesting of fuel wood and expansion of agricultural land. Nearly half of country’s forest cover is found in the state of M.P. (20.7%) and seven states of North East (25.7%) . There is net forest loss at rate of 0.2%. These trends combined with increasing industrial and motor vehicle pollution output have led to atmospheric temperature increases and shifting precipitation patterns.
  2. 2. SOIL DEGRADATION When plants (trees & shrubs) are cleared from a site, soil is exposed to sunlight and the eroding effects of wind and water. Soil aeration is increased and the rate of weathering increases. Apart from erosion, the proportion of organic matter in the soil gradually decreases, through the action of microbes in the soil which use it as a source of energy unless the new land use provides some replacement.
  3. 3. CAUSES OF SOIL DEGRADATION FORMS OF SOIL DEGRADATION IMPACTS • The main impact of soil erosion is the reduction in soil quality which results from the loss of the nutrient-rich and fertile upper layers of the soil, and the reduced water-holding capacity of many eroded soils. In other words, 'Erosion removes the cream of the soil' ( Therefore soil erosion is one of the most serious threats to soil fertility. Even low erosion rates which are almost invisible can over the years have a severe impact on soils. It is therefore of vital importance to protect the soil from erosion. Especially organic farming fully depends on maintaining the natural fertility of the soil. • Soil erodibility is an estimate of the ability of soils to resist erosion, based on the physical characteristics of each soil. Generally, soils with faster infiltration rates, higher levels of organic matter and improved soil structure have a greater resistance to erosion. Sand, sandy loam and loam textured soils tend to be less erodible than silt, very fine sand, and certain clay textured soils.
  4. 4. Soil conservation measures • Certain conservation measures can reduce soil erosion. Soil / land management practices such as tillage and cropping practices, directly affect the overall soil erosion problem and solutions on a farm. When crop rotations or changing tillage practices are not enough to control erosion on a field, a combination of measures might be necessary. For example, contour plowing, strip cropping, or terracing may be considered.
  5. 5. Types of conservation measures: • Agronomic: such as plant / soil cover, conservation farming methods, contour farming • Vegetative: such as planting barriers (vegetative strips), live fences, windbreaks • Structural: such as Fanya Juus, terraces, banks , bunds, cut off drains, barriers • Overall management: such as area closures, selective clearing