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Soil Erosion: At War with Nature’s Home Turf

Corroding our Foundations

Soil Erosion is the destruction and removal of the fertile top layer of soil at a rate faster than the rate of its natural formation. Soil is weathered rock. Topsoil is the upper, fertile layer that supports growth of plants – forests, pastures, farms, plantations etc. Subsoil is the lower layer that does not sustain plant growth.

Although a part of land degradation, soil erosion merits a more detailed treatment because soil is among the most valuable natural resources that fosters plant growth and, thereby, makes life possible. Plants provide food and fodder, absorb harmful gases, maintain natural balance, supply industrial raw materials, and deliver fuel.

 

Types

Water, wind, and tillage are the three main agents of soil erosion. High-speed winds such as cyclones and dust-storms carry away loosened soil particles. Tillage redistributes soil causing it to move down the slope and prepares ground for erosion by water.

Flowing Water destroys topsoil in three ways:

  • Sheet Erosion is the removal of loosened topsoil on relatively flat terrain as wafer-thin sheets
  • Gully Erosion results on terrains with gradient and some vegetative cover that slows water flow. Water then cuts minute and shallow channels called rills that expand and merge into broader gullies. Left unchecked, this can aggravate into ravines or badlands
  • Bank Erosion or the eating up of channel banks

 

The Depreciators 

Natural forces and human interference are both responsible for loosening and transportation of topsoil. Human activities wear away soil by themselves and intensify the effect of nature. Forces of nature that destroy and transport topsoil include:

  • Torrential Rains, Flash Floods, and Cyclones
  • Grazing and Burrowing Animals
  • Wildfires
  • Earthquakes

Anthropogenic activities that promote soil erosion include:

  • Deforestation means roots of trees and grasses are not able to hold soil particles together. Leaves and branches of trees can no longer slow down falling raindrops that are left free to corrode topsoil
  • Incorrect Agricultural Practices such as tilling in the direction of wind and water flow, excessive use of water, allowing fast flow of water through fields, and use of large doses of chemicals and fertilizers that harden topsoil
  • Overgrazing
  • Unsustainable Mining creates voids beneath soil causing collapse of the land above
  • Flawed Constructions on hill slopes, cleared forests and pastures, and farmlands

 

 

Fallouts

  • Loss of Soil Fertility has grave implications for the production and availability of food, fodder, fuel, and industrial raw materials
  • Barren-isation and Desertification of Land as it progressively loses its capacity to support life. Communities dependent on such lands are disintegrated and forced to migrate
  • Floods result from soil particles accumulating in river channels and decreasing its water holding capacity. Floods further erode soil and the vicious cycle continues
  • Decline in the Storage Capacity of Reservoirs such as dams, percolation tanks, and natural lakes can spell doom for those dependent on these waterholes

Soil Conservation

Conservation relies on prevention of loosening of soil particles and slowing down the agents that carry these down-slope or downwind. Green Cover reduces impact velocity of raindrops on soil and holds soil particles together against flowing water and blowing wind. Specifically:

  • Slowdown of Flowing Water by:

+      Contour Farming or planting trees / crops along the same level across the slope

+      Terraced Farming is farming on steps / terraces cut out of slopes

  • Wind Breaks through:

+      Shelter Belts or rows of high trees

+      Strip Farming is the planting of strips of grass between crops on large fields

  • Maintain Soil Cohesion by:

+      Crop Rotation and Fallow allow replenishment of soil nutrients and maintain soil compactness

+      Shallow Tillage with Minimum Tillage Passes

+      Check Overgrazing and Over-burrowing


 

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