Soil Erosion and Conservation

SOIL EROSION AND CONSERVATION

Erosion

Erosion is the removal of soil particles by the motion of wind or water. Soil erosion is one of the major concerns of modern agriculture throughout the world.

The fallowing contributes to soil erosion:

п‚ў Misuse of land,

п‚ў Mismanagement of arable land,

п‚ў Indiscriminate felling of trees,

п‚ў Overgrazing,

п‚ў Poor soil and water management

Erosion causes or Results in a:

п‚ў Decline in soil fertility,

п‚ў Water supply,

п‚ў Crop yields.

п‚ў Thus it affects the productivity of the land,

п‚ў This decreases the production of food, feed, fiber, and fuel.

п‚ў This adversely affects the socio-economic conditions of the state.

п‚ў Erosion causes floods,

п‚ў Silting up of water reservoirs,

п‚ў Disruption of communication systems,

п‚ў Disturbance of the socio-economic setup of the farming community.

Erosion is of Two Types.

1. Normal or Geological Erosion:

Erosion effects are not visible on the land surface nor are soil productivity adversely affected. In quantitative terms, the amount of soil lost through erosion is equal to the amount of soil formed.

2. Accelerated Erosion:

The effects of erosion are visible on the ground surface and the rate of soil loss is greater than the rate of soil formation.

Magnitude of the problem in Pakistan:

According to an estimate;

 Wind and water erosion affect over 76% of the country’s total area.

п‚ў Over 36% is being eroded by water and 40% by wind.

п‚ў Every year approximately one billion tonnes of soil is being lost, silting up precious dams and dumped into the Arabian Sea.

п‚ў Most erosion takes place during the summer because about 60-45% of the precipitation falls in that season in the form of heavy downpours.

Erosion is mainly caused by two agencies: Wind and Water.

п‚ў Erosion caused by wind is called -wind erosion

п‚ў And that caused by water is called water erosion.

п‚ў These two processes are active around the world all the time.

Water Erosion

п‚ў Erosion caused by water is called as - water erosion

Mechanics of water erosion:

The first impact of raindrops on the soil is the breaking up of soil clods. This can only occur if there is no vegetative cover.

п‚ў When raindrops fall on bare, unprotected soil, soil clods are broken into small particles which are suspended in the accumulated water.

п‚ў Some of muddy suspension flows down the slopes in the form of runoff, and part of it percolates downwards into the soil.

п‚ў When the muddy suspension enters the soil, suspended material is deposited in the soil pores, which affects the infiltration capacity of the soil.

п‚ў The continuous deposition of solids seals the soil pores and the further intake of water ceases.

п‚ў Consequently more and more water is lost as runoff.

Forms of water erosion

There are four stages of soil erosion by water:

(i) Raindrop or splash erosion

(ii) Sheet erosion,

(iii) Rill erosion, and

(iv) Gully erosion.

i. Raindrop or splash erosion is the first stage of water erosion.