5 Facts you need to know about the soil erosion

  ^{5 facts you need to know about the soil erosion}

   

    1.      Why top soil layer of the planet is important?

Generally, five layers are found in the soil profile of the earth. Besides, top soil layer is considered as the most important layer of the soil. It functions as the life sustaining layer of the earth as its contain lots of nutrients results from the degradation of plant materials, dead bodies of animal, and  animal’s fecal matter. Moreover, the most parts of the nutrients cycles also process in the top soil layer. Thereby, its nutrient supply and microclimatic conditions like high moisture content and optimal temperature together provides ideal growing medium for the Earth’s plants.

    2.      What is soil erosion?

The soil erosion is defined as the dislodgement of the soil particles from the top soil layer. Soils in the surface soil layer is too light and are easily displaced by natural agents like wind and water.

Although it is a natural phenomenon and it happens occasionally at a slow rate, uncontrolled anthropogenic activities have intensified the rate and frequency of the soil erosion.

3.      What are the causes of soil erosion?

Soil erosion is caused and enhanced by both natural agents as well as man induced factors.

Natural agents

1) Wind

Strong winds blowing across the uncovered areas of the Earth like deserts are able to carry away the soil particles and organic matter in the top soil layer.

2) Water

Rains along the mountains or over the slope areas causes dislodging and washing away the top soil layers.  Extreme rainfall events are enough to loss of significant area of the land mass by the massive forms of soil erosions like gully or rill erosion.

Human induced activities

1) Intensified agriculture

Conversion of a forest ecosystem into large farm areas results in the loss of its valuable top soil layer. Generally, forest ecosystem is comprised of a large number of trees with deep roots, grasses, and shrubs with shallow roots system. The deep root system of trees help to hold the soil particles in the region. In addition, organic matters results from decaying plants and animals and dead root improve the soil structure by increasing the formation of the soil aggregations. In addition, plant materials in the forest floor acts as natural mulch that prevent the direct contact of rain droplets with soil particles. Tress have extensive canopy that spread over a large area. The branches and leaves of large trees reduce the speed of rain droplets coming towards the floor. Thereby, the natural ecosystem are built up in a way that minimize the soil erosion even by the natural agents.

Crops are grown in a certain distance in order to optimize their growth and management. And also, they have relatively shallow root system. This conditions cannot support to hold the soil particles together. As the crops does not produce extent canopy, they cannot slow down the water flow through them.  Since a significant fraction of mulch lost during the land preparation for the farming and these crops does not produce much organic matter, most of the land area expose directly to wind and rain.

Furthermore, the conventional farming practices like tillage also intensify the soil erosion by disturbing and exposing land areas. Crop cultivation in unsuitable environments like along steep areas also leads to displacement of a large amount of soil particles in those areas.

2) Deforestation

Deforestation is a side effect associated with many human activities like construction and expanding of roads, buildings and power plants, establishment of human settlements, and intensive crop cultivation.

Cutting down larges forests and human activities without appropriate measures to control the soil erosion leads to loss of a large amount of Earths valuable soils.

3) Overgrazing

Long-term uncontrolled grazing over a same grassland also increase the magnitude of the soil erosion of the area. It removes the surface plant cover and lead to formation of bear land. The hooves of animals are also capable of uprooting the grasses.

                4.  What effects of soil erosion?

1) Reduce productivity of agricultural lands

During past few decades, nearly half of planet’s surface soil layers have been lost. Nutrients attach to the positive and negative ion exchange sites of soil particles. Loss of soil particles also causes the loss of nutrients bound to them. Consequently, soil of arable lands become less fertile and no longer support for the growth of plants. Because, after washing away of the top soil layers, sub soil layers expose to the environment. These sub surface soil layers are often poor in nutrients and unable to attain optimize plant growth.

2) Frequent floods

The loss of top soil alone with its organic matter reduces the soil aggregations. It decreases the infiltration capacity of the degraded soils. Consequently, it increases the surface runoff and increases local flooding incidents.

3) Pollution of water ways

Accumulation of the soil particles coming from the soil erosion in the uplands negatively effects adjacent water bodies. Settling down in the light soil particles within the water column decreases the light penetration and increases the turbidly. Deposition of soil particles on aquatic animals like shellfishes, destroying their habitats and breeding ground threats the life of aquatic life. The capacity of reservoirs also decrease due to accumulation of sediments at the bottom of water body. Consequently, frequency and intensity of flooding in the area increases.

The nutrients like nitrogen, and phosphorous also reach into the water body alone with the soil particles. It increases the availability of nutrients for aquatic plants and algae. The excess nutrients enhance the growth of these plants and algae and results in the development of algal blooms. With time algal blooms alone are responsible for the transforming the living aquatic ecosystem into a dead ecosystem by killing all living beings.

5.      What are preventive and controlling measures of soil erosion?

1)      Crop rotation

Fellow time of a land is referred to as the time between harvesting and uprooting existing crops and starting next cropping. During this period, crops are not grown in the land and allow the natural vegetation regrow and sustain the lands.  It help to increases the organic matter content in the soil and improve the soil structure. Thereby, plants in the fellow period reduce the soil erosion of the land.

2)      Agroforestry system

Rather than growing mono culture, agroforestry system can be established to overcome the most of the problems associated with the conventional farming system. Because, the agroforestry involve the planting crops with tree species alternatively. It allows for the establishment of deep root system in the farming lands.

3)      Use of mulch

The surface of agricultural areas should be covered by using appropriate type of mulch. A thick layer of mulch should be spread over the surface of the land to form a mat. It prevents the direct contacts of soil particles by the rain. When soil become too dry, soil particles are easily detached away by the winds. So application of mulch helps to keeps the moisture in the soil and minimize the transpiration. Saw dusts, straws and leaves are used as the natural mulch. In addition to protecting soil moisture content, natural mulch also provides nutrients for the growing plants. Artificial mulch made of synthesized materials are used for the farming.

4)      Wind barriers

A belt of trees should be grown around or existing trees around the cultivation land should not be removed. It can break the speed of the strong wind prevailing across the land. As a results, weak winds cannot dislodge soil particles as much as the strong winds do.

5)      Trace farming

Instead of cultivation along the slopes, plants are grown in the steps cutting down along the slope. It help to slow down the water flow across the land and minimize the carrying soil particles through runoff by retaining soil particles in the steps.