The Soil Erosion

Soil is one of our most precious resources in this world. Soil erosion is a natural process and has occurred throughout geological history. The loss of this resource, though land degradation processes such as wind and water erosion, is one of the most serious environmental problems.

Types of Soil Erosion

In general, there are several types of soil erosion which are rain drop or splash erosion, sheet erosion, rill erosion, gully erosion and stream bank erosion. The rain drop or splash erosion is the erosion which preceded by the destruction of the crumb structure due to the impact of falling raindrop on the surface of soil is termed as splash erosion. The sheet erosion is the fairly uniform removal of soil in thin layers from the land surface, often scarcely perceptible, especially when caused by wind. The areas where loose, shallow topsoil overlies compact soil are most susceptible to sheet erosion. The rill erosion is a form of water erosion in which numerous very small and more or less straight channels are produced; the channels get obliterated by ordinary use. It can be removed by normal tillage operations. Apart from that, the gully erosion is a form of water erosion in which gullies are produced by combination of unattended rills. The stream bank erosion is stream banks are eroded by water either flowing over the sides of a stream or scouring at the base.

Cause of Soil Erosion

The main cause of the soil erosion is due to the human activities. The human activities such as agriculture activities bring lots of damage to soil and dirt. Many farmers attempt to restore soil fertility by adding fertilisers or artificial nutrients but some countries do not have this opportunity due to poverty or lack of education.  In South America soya is a quick-growing and valuable crop. Despite some artificial fertilisers being added the soil is not allowed enough time to recover its fertility or structure and is ultimately being eroded by this human activity. Deforestation also a kind of activities which caused soil erosion. The removal of trees without sufficient reforestation has resulted in damage to habitat, biodiversity loss and aridity (drying of soil).  This human activity quickly accelerates natural erosion in two ways.  Firstly the removal of trees is a removal of nutrients and minerals from the soil as the source of humus is greatly reduced.  The natural dead organic material that supplies the soil with its humus is generally leaves that have fallen from the trees, animal droppings, tree fruit or decaying trees in the soil.  Secondly, deforestation accelerates soil erosion by leaving large areas exposed to heavy rainfall (which can cause leaching or flash floods) or wind erosion.   Without the roots of the trees to keep the soil structure in place the soil is loose and easier to erode.  The tropical rain forests of Brazil are seeing huge areas of forest being cut down each day.  Each year about 13 million hectares of the world’s forests are lost due to deforestation.   

Figure 1: Deforestation in Brazil 2002 to 2008

Effect of Soil Erosion

            The soil erosion will cause the reduction in water quality. The eroded soil which contain the nutrients, fertilities and herbicides can be deposited. At the same time it can cause the reduction in the slope of land. In general, the heavier soil particles will be deposited during the soil erosion, while finer colloidal clay remain in suspension. The soil removed by gully erosion may be transported directly to rivers.

Solution of Soil Erosion

            However, there’s some ways to avoid or prevent soil erosion. One of the ways to avoid the erosion of soil is to reforestation. Reforestation is the deliberate planting of trees. This may occur in areas of deforestation, mountain slopes or as a general practise to plant a seedling for each tree cut down. EU legislation now controls the minimum height and age of tree that can be cut and also offers incentives to farmers to turn part of their land over for forestry. In areas like the Apennines in Italy or the mountainous terrain of the West of Ireland this is seen as a valuable alternative to crop or animal farming. The EU forestry grant aid is the initiative to attract farmers to grow and maintain areas of forestry. In the 1900’s only half of one percent of Ireland was classified as under forests but due to a change in laws and funds this has risen to over twelve percent. The policy of ‘cut one, plant two’ is hoping to see an increase in this figure and, in turn, the slowing down of the rate of soil erosion.