What is soil erosion and soil degradation. Discuss the causes of soil erosion.

 Q:-  What is soil erosion and soil degradation.  Discuss the causes of soil erosion.

Answer :-    SOIL EROSION :- 

The process in which the light and unconsolidated soil particles on the surface of the soil are separated and moved far away on the surface of the soil under the influence of various natural forces and human activities is called soil erosion.

SOIL DEGRADATION :- 

When soil fertility is lost as a result of soil erosion, physical and chemical properties change and quality decreases, it is called soil degradation or soil degradation.

   Causes of soil erosion :-

(a) Natural causes :-  

(1) Rainfall and runoff :-  

Rainwater is the main means of soil erosion.  Through surface runoff, rainwater washes and transports soil minerals and organic matter.  Rapid infiltration of rainwater into the soil degrades soil quality by carrying surface minerals downward in the leaching process.  Heavy rains in torrential rains lead to soil erosion through drainage and erosion, leading to increased soil degradation.  Large raindrops hit soil grains directly and break them.

(2) Wind flow :-

In desert or semi-desert areas and on sea coasts, loose sand, dust and soil are carried away by strong wind currents and the soil erodes rapidly.  The seashore is broken by the continuous strong impact of the sea waves and the soil and stones are removed.  

(3) Sea waves :-

The tidal currents and destructive sea waves break the seashore and remove the soil and stones.

(4) Topography and land slope :-

  As the slopes of mountains and plateaus are steep, land erosion is accelerated due to rapid flow of water and landslides.  But in the plains the water flows slowly and the erosion is very less.

(5) Nature of rock and soil :-

Sedimentary rock soil is porous and soft as compared to igneous and metamorphic rock and is easily affected by erosion.  If the soil is coarse grained, rapid infiltration of water leads to degradation of soil quality.  If the soil is fine grained, surface runoff causes rapid soil erosion.  Soil erosion is more when soil particles are loosely attached.

(b) Human causes :- 

(1) Cutting of trees :- 

Vegetation cover prevents the sedimentation and transport of soil particles by resisting the direct impact of raindrops on the soil. Plant roots, trunks, fallen leaves prevent soil erosion by reducing the velocity of surface runoff of rainwater.  As the roots of plants and grasses cling to the soil particles, the particles are not easily dislodged by raindrops.  But with population growth, humans accelerate land degradation by destroying forests and grasslands.  

(2) Indiscriminate grazing :-

Unscientific grazing of limited pastures results in the elimination of grass and loosening of the soil.  Moreover, the foot pressure of animals damages the grasslands and accelerates soil erosion.

 (3) Unscientific Farming :-

Due to the indiscriminate use of tractors, harvesters, the soil is easily broken and loosened and subjected to erosion.  Uncontrolled use of pesticides, chemical fertilizers, irrigation destroys soil cohesion.  Soil erosion is very easy.  In hilly areas, shifting cultivation or jungle cultivation leads to loss of forests and erosion of topsoil.

 (4) Construction work :-

Nowadays , due to the construction of houses, roads, bridges, industries, dams, reservoirs, canals, ponds, trenches, sewers, mines by man, the soil surface becomes loose and weak.