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Soil Erosion

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Agricultural Processes
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Rain has eroded the soil, except where protected by small stones.
Soil erosion
is the removal, or loss, of soil due to water, wind, or excessive tillage. It results in the loss of topsoil and the loss of soil from farmland, which is reflected in reduced crop production potential, lower surface water quality, and damaged drainage networks.

Soil is naturally removed by the action of water or wind, this is known as geological erosion, which has been happening on the Earth for about 450 million years. Geological soil erosion removes soil at approximately the same rate as it is being formed.

Problems occur when erosion is accelerated, meaning soil is lost at a faster rate than it is formed. This is a result of human actions such as overgrazing and unsuitable cultivation practices, which leaves land unprotected and vulnerable. Accelerated soil erosion is the most widespread of today’s environmental problems; it affects both agricultural areas and the natural environment. The impact is both on-site (where the erosion happens) and off-site (where the soil ends up). More recently, the use of powerful agricultural implements has led to the damaging of soil; this is known as tillage erosion.

Soil erosion is only one form of soil degradation; other kinds include salinisation, nutrient loss, and compaction.

Contents

[edit] Effects of Water Erosion

The rate and magnitude of soil erosion by water is determined by rainfall intensity and runoff, soil erodability, slope gradient and length, vegetation, and conservation measures.

[edit] Sheet and Rill Erosion

Sheet erosion is soil movement from raindrop splash, which results in the breakdown of the soil surface structure and surface runoff. It occurs uniformly over the slope and may go unnoticed until most of the productive topsoil is lost.

Rill erosion results when surface runoff concentrates, forming small, but well defined channels. These channels are called rills when they’re small enough to not interfere with field machinery operation.

[edit] Gully Erosion

Surface runoff causes gull formation, or the enlarging of existing gullies, and is usually the result of improper outlet design for local surface and subsurface drainage systems. This creates soil instability, which, when associated with seepage of ground water, leads to the caving of bank slopes. This usually occurs during the spring, when soil water conditions are most conducive to the problem. Gully formations are difficult to control if the remedial measures are not properly designed.

[edit] Stream and Ditch Bank Erosion

This type of erosion is due to poor construction or inadequate maintenance of surface drainage systems, uncontrolled livestock access, and cropping too close to stream banks. Bank erosion can cause the loss of productive farmland, damage nearby structures such as bridges, and wash out lanes, roads, and fence rows. Some on-site effects include the loss of natural crop nutrients, seeds and plants being disturbed or removed along with organic matter from soil and pesticides. Off-site effects can include damaged roads due to deposited sediment, and contamination or pollution can result in water sources and recreational areas.

[edit] Effects of Wind Erosion

The rate and magnitude of wind erosion is controlled by climate, erodability of soil, soil surface roughness, unsheltered distance, and vegetative cover. Wind erosion can completely ruin crops, cause soil drifting, or the loss of organic particles.

[edit] References