Soil Erosion, Its Impacts and Conservation

Soil erosion refers to as the movement of soil particle form one place to another place. It is a natural process. It occurs at relatively slow rate and its magnitude is unnoticed. Wind and water are the major two agents of natural soil erosion. Due to the anthropogenic activities, quality of the soil is degraded. Thereby soil makes more vulnerable to soil erosion. Continuous removal of topsoil from agricultural lands affects the crop yield and environment quality.

·        Driven factors of soil erosion:

1)    Deforestation: Cut down and remove of vegetation from land left bare soil.  It makes the soil more vulnerable to both wind and water erosion. Removal of vegetation directly affects the organic matter content in the soil. Due to the low organic matter availability, soil particles are not aggregated together. Fine soil particles of topsoil are more easily wash away or blown from the surface. Due to the absence of vegetation wind has the opportunity to directly contact the soil surface.

2)    Overgrazing: Unregulated grazing of livestock reduces the thickness of the grass layer of pasture lands so it makes more vulnerable to erosion. Livestock press topsoil into the subsoil. It reduces the infiltration capacity of the soil. So it increases the runoff. Thereby it increases the amount of soil to move through the water.

3)    Tillage: Although tillage brings lots of advantages for agriculture, improper tillage practices cause negative consequences. Tillage buries topsoil and brings subsoil into the upper surface. It increases the surface area of soil exposed to wind and rain.

4)    Construction of roads and other infrastructure: Soils has to be removed in large scale in road and railways constructions.

5)    Mining: gem mining and coal mining processes dig and remove a large portion of topsoil and subsoil from the land.

Water erosion: runoff is able to dislodge the fine soil particles from the soil surface. It causes onsite effects and offsite effects.

1)    Gully erosion: As a result of the high flow of velocity, the deep channel is formed by the removal of soil and soft rocks. Riverbank is subjected to gully erosion due to the high velocity of river flow. After heavy rain, gully erosion also can be observed at the bottom of the sloppy area.

2)    Sheet erosion: It is the removal of the soil particles from the surface by a thin layer of water. It removes soil more uniformly over the surface. As it happens at a slow rate, it cannot be easily observed until a significant amount of topsoil is lost.

3)    Rill erosion: It forms well defined small channels over the surface as a result of strong surface runoff. It can be observed in steep land and lands with gradual sloping.

Wind erosion: It is abraded, transports, and deposes of soil by the action of wind.

Onsite effects of erosion:

1)    Reduce crop yields: topsoil is the most fertile layer of soil that directly affects plant growth. It contains organic matter, nutrients, and microorganisms in large quantities. It is continuously replenished by litterfall, organic matter decomposition, nutrients cycling, and mineral weathering. After the loss of topsoil, subsoil falls to fulfill all nutrient requirements of the plant which results in a reduction of crop yelled.

2)    Reduce land stability: Continuous removal of soil makes the land prepare for the landslides.it causes loss of people, ecosystem and properties.

Offsite effects:

1)    Siltation of aquatic bodies: Soils particles that are washed away from the land tend to deposit at the bottom of the lakes or streams. It reduces the water holding capacity of the aquatic body which increases the flood risk of the area. Soils deposit in the bottom vegetation. So it interferes with the breeding places and habitats.

2)    Eutrophication: Excess nutrients including phosphates and nitrates bound soil particles to accelerate the growth of algae in the aquatic ecosystem. The sudden increase of algal growth refers to as the algal bloom. Some algal species produce toxic substances that are toxic to animal and plant life.

3)    Aquatic pollution: The soil acts as itself pollution. Dissolved soil increases the turbidity which results in a reduction of light penetration through the aquatic bodies. Thereby the productivity of deep layers of aquatic bodies is reduced. In addition to nutrients, pesticides also attach to soil particles toxic to aquatic animals. They tend to accumulate through the food web and cause detrimental effects on the animals at the top levels.

·        Following actions are suggested to minimize the erosion by wind or water.

1)    Mulching: organic mulches including fiber woods and straw, plastic and rubber mulching and geotextile material is used for agriculture to minimize soil erosion. It prevents the direct exposure of soils to winds. In addition to erosion protection, organic mulch protects the moisture content in the soil and improves the soil structure.

2)    Avoid overgrazing: it is allowed livestock to feed on pasture land till a certain limit to recover the vegetation again.

3)    Add organic matter: Organic matter is able to glue small soil particles together to form large aggregates. So soils cannot be detached from the land. Compost can be added as the organic matter.

4)    Maintain vegetation cover: The root systems of the plant helps to hold the soil particles in the places. They secrete glues which are helped to bind fine soil particles into large aggregates. Thereby they protect soils against water erosion. Thick vegetation cover prevents reduces wind velocity and does not allow it to contact the soil. Thereby it protects the soil against wind erosion.

5)    No-tillage or conservation tillage: Conservation tillage means to increase crop yield while taking actions to protect the soil against wind erosion and water erosion. Here tillage is not used from sawing to harvest or use minimum tillage.