Soil erosion (IGKV RAIPUR, C.G)

Soil erosion (IGKV RAIPUR, C.G)

1. INDIRA GANDHI KRISHI VISHWAVIDYALAYA, RAIPUR

2. SOIL EROSION Mining of soil erosion:- Soil erosion is the process of detachment of soil particles from the parent body and transportation of the detached soil particles by wind and water. The agents causing erosion are wind and water. The detaching agents are falling rain drops, channel flow and wind. The transporting agents are flowing water, rain splash and wind. Depending on the agents of erosion, it is called as water erosion or wind erosion or wave erosion.

3. Definition of soil erosion :- “Soil erosion is the wearing away of the land surface by physical forces such as rainfall, flowing water, wind, ice, temperature change, gravity or other natural or anthropogenic agents that abrade, detach and remove soil or geological material from one point on the earth’s surface to be deposited elsewhere.”

4. Extent of soil erosion;- Soil Erosion in India is amongst the leading areas of concern for the Government of India. It affects cultivation and farming in the country in adverse and unfavourable ways. Soil erosion leads to deprivation of physical characteristics of soil and damages plant and crops. In India almost 130 million hectares of land, that is, 45% of total geographical surface area, is affected by serious soil erosion through gorge and gully, sifting cultivation, cultivated wastelands, sandy areas, deserts and water logging.

5. Extent of soil erosion;- Soil erosion by rain and river that takes place in hilly areas causes severe landslides and floods, while cutting trees for agricultural implements, firewood and timber; Grazing by a large number of livestock over and above the carrying capacity of grass lands, traditional agricultural practices, construction of roads, indiscriminate quarrying and other activities, have all led to the opening of hill-faces to extreme soil erosion.

6. Extent of soil erosion;- A joint FAO/UNEP assessment of land degradation around the world has come up with the following findings; In Africa north of the equator, 11.6% of the total area is affected by water erosion and 22.4% by wind erosion. In the Near East, 17.1 % of the total area is affected by water erosion; 35.5 % by wind erosion, and 8 % by salinization.

7. TYPES OF SOIL EROSION Natural or Geologic Erosion Accelerated Soil Erosion Water Erosion:- Splash Erosion Sheet Erosion Rill Erosion Gully Erosion Stream-bank Erosion Wind Erosion:- 1) Deflation Surface creep Saltation Suspension 2) Abrasion

8. TYPES OF SOIL EROSION A) Natural or Geologic Erosion:- It is caused by nature. Normal or geologic erosion is a normal feature of any landscape. Geologic erosion takes place gradually but so slowly that ages are required for it to make any noticeable alteration in the major features of the earth’s surface. B) Accelerated Soil Erosion:- It is caused by human activities. This accelerated detachment that rapidly ravages the land and it is with this type of soil erosion that is considered of a serious concerned. Nature requires, on an average, about 1000 years building 2.5 cm’s of top soil but wrong farming methods may take only a few years to erode it from lands of average slope.

9. TYPES OF SOIL EROSION C) Water Erosion :- Water erosion causes severe soil erosion and this category of soil erosion can be defined, splash erosion, sheet erosion, rill erosion, gully erosion and stream-bank erosion. 1) Splash Erosion:- Splash erosion is the first stage of the erosion process. It occurs when raindrops hit bare soil. The explosive impact breaks up soil aggregates so that individual soil particles are ‘splashed’ onto the soil surface. The splash particles can rise as high 60cm above the ground and move up to 1.5 meters from the point of impact The particles block the spaces between soil aggregates, so that the soil forms a crust that reduces infiltration and increases runoff.

10. TYPES OF SOIL EROSION 2)Sheet Erosion:- In the initial stages of soil erosion, rain drops churn the top soil and along with runoff the muddy water moves away from the field. It is uniform removal of top soil in thin layer from the field. It is least conspicuous and is the first stage of erosion.

11. TYPES OF SOIL EROSION 3) Rill erosion:- When runoff starts, channelization begins and erosion is no longer uniform. Incisions are formed on the ground and erosion is more apparent than sheet erosion. This is the second stage of erosion.

12. TYPES OF SOIL EROSION 4) Gully Erosion:- Unchecked rills result in increased channelization of runoff. Gullies are formed when channelized runoff from vast sloping land is sufficient in volume and velocity to cut deep and wide channels. Gullies are the most spectacular symptoms of erosion. If unchecked cultivation becomes difficult.

13. TYPES OF SOIL EROSION 5) Stream-bank Erosion:- Small streams, rivulets, torrents (hill streams) are subjected to stream-bank erosion due to obstruction to their flow. Vegetation sprouts when the streams dry up and obstructs the flow causing cutting of bank or changing of the flow course.

14. TYPES OF SOIL EROSION D) Wind Erosion:- Wind erosion is the movement and deposition of soil particles by wind. Wind erosion is a serious problem in area where land is bare and devoid of vegetation. It is a natural phenomena in arid and semi-arid zones. When it’s velocity overcomes the gravitational and cohesive forces of the soil particles, wind will move soil and carry it away in suspension. Wind erosion is of two primary varieties: 1) Deflation:- Where the wind picks up and carries away loose particles. 2) Abrasion:- where surface are worn down as they are struck by airborne particles carried by wind. Deflation is divided into three categories: Surface creep Saltation Suspension

15. TYPES OF SOIL EROSION

16. TYPES OF SOIL EROSION 1) Surface creep:- (1) Rolling of coarse grains, larger than 0.5 to 3 mm in diameter and too heavy to be lifted, by wind along the surface of the ground is called surface creep. (2) The particles are pushed along the surface of the ground, rolling and not jumping. (3) Generally, 5 to 25 % weight of the soil lost by wind erosion is carried in surface creep. 2) Saltation :- (1) Saltation is the first stage of movement of soil particles in series of jumps. (2) The soil particles moved by saltation are between 0.1 to 0.5 mm in diameter(fine sand). (3) Sand sized particles rolling along the surface start this movement. (4) Due to the effect of wind, soil particles jump up vertically into air and rice to a height of 30 to 60 cm and fall through the air. (5) Generally 50 to 75 % of the weight of soil lost by wind erosion is carried in saltation .

17. TYPES OF SOIL EROSION 3) Suspension:- (1) Floating of fine dust particles through the air is known as suspension. (2) The particles are smaller then 0.1 mm in diameter. (3) The smaller particles are kicked into the air, they stay in suspension and carried very long distances, even several thousands of kilometres. (4) The dust comes down to earth only with rain or when wind velocity is decreased. (5) Generally 3 to 4 % of the weight of soil lost by wind erosion is carried in suspension.

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