Soil Erosion Causes, Types, Soil Conservation Methods

Soil Erosion and Soil Conservation:

Today, we are discussing Soil Erosion Causes, Types, Soil Conservation Methods.

Introduction to Soil Erosion:

Soil Erosion is the main problem in Agriculture. Tonnes of soil are gone from the fields every year. This not only reduces crop cultivation, but the soil also acts as a pollutant to rivers, lakes, and other water systems. Soil Erosion controlled with the proper techniques.

Soil Erosion is the displacement of the upper layer of soil, one type of soil degradation. This natural method is caused by the dynamic activity of erosive agents, that is, water, ice, snow, air (wind), plants, animals, & humans. In accordance with these agents, erosion is sometimes separated into water erosion, glacial erosion, snow erosion, wind erosion, zoogenic erosion, and anthropogenic erosion. Soil erosion may be a slow procedure that continues relatively unnoticed, or it may happen at an alarming rate causing a serious loss of topsoil. Prevention of soil Erosion is also known as conservation of soil.

Soil Erosion factors:

Soil Erosion is dependent on many factors:

• The climatic environment of the area
• The proportion of sand, silt, and clay-sized particles in an exacting soil
• The organic matter stage
• Water permeability of the soil
• The length & slope of the field
• The amount of crop rotation
• The direction of cultivation

Causes of Soil Erosion:

Various agents, like wind, water, deforestation, overgrazing by cattle, and etc., cause soil erosion. The different factors of Soil Erosion are:

Wind:

When strong winds blow, the topsoil along with the organic substance is carried away by the wind. These occur more often when the land is not covered with grass or plants. Such conditions are extremely common in desert and semi-desert regions where strong winds blow very frequently.

Water:

When it rains in the hilly areas, the soil gets cleaned away towards the plains. The running water deposits the mineral-rich soil in the riverbed & over the years, this deposition of soil can change the course of the river. This can lead to floods which cause the destruction of life & property.

Overgrazing:

When cattle are allowed to graze on the similar field repeatedly, all the available grass, including the roots is eaten by them. This makes the topsoil vulnerable to wind & flowing water, leading to Soil Erosion.

Deforestation:

Humans have taken land from the forest to cultivate in order to feed the ever-increasing population & to build houses, industries, etc. Cutting down of trees on a big scale for these purposes is deforestation. The roots of trees hold the soil jointly, thus preventing the soil from getting uprooted. When large areas of the forest are cleared, the topsoil gets eroded by wind & flowing water.

Geographic Location:

The severity of Soil Erosion varies from place to place. Wind and water are the major causes of soil Erosion. The faster either moves or the amount of plant cover available for protection are two main factors associated with erosion. Wind erosion is a more general problem in dry, windy regions, with a smooth, flat terrain.

Types of Soil Erosion:

1. Water Erosion: It is caused by the action of water, which removes the soil from falling on as raindrops as well as by its surface flow action. Depending upon the type of the lost soil, it may be:

      (a) Sheet Erosion: The removed soil is similar to a thin covering from a large area. This sheet is lost more or less regularly.   

(b) Gully erosion: This results due to the convergence of some rills towards the steep slope, which form together wider channels of water, known as gullies.

2. Wind erosion: It is ordinary in dry regions where the soil is chiefly sandy & the vegetation is very poor or even absent. Once the topsoil is laid bare to the fury of strong winds, it gets blown off in the form of dust storm & sand storm. Wind erosion may be of the below three types:

(a) Saltation: In the arid regions of low rainfall, drainage is poor & high temperatures prevail. Water evaporates speedily leaving behind the salts. Salt accumulation occurs mostly in the lowlands around the oceans. The salts are mostly chlorides, sulphates, carbonates, and nitrates of potassium, magnesium and sodium, and chlorides & nitrates of calcium.

(b) Suspension: The winds throw away the smallest soil particles in the air, which moves like a fine clust with the wind. By this way, soils are transported to moderately long distances.

(c) Surface creep: the heavier particles of soil that are not simply thrown up by wind are basically pushed or spread along the surface by wind.

3. Landslides or slip erosion:

The hydraulic pressure caused by heavy rains increases the weight of rocks at cliffs which come under the gravitational force and finally slip or fall off.

4. Streambank erosion:

The rivers during floods splash their water against the banks & thus cut through them. Mostly at meanders. This type of erosion is called riparian erosion.

5. Deforestation and over-grazing:

Deforestation makes soil cover vulnerable to wind & water erosion. Overgrazing is the main hazard affecting pastures, forests, and mountains. Grazing destroys the little cover & enhances wind and water erosion.

Methods of controlling Soil Erosion:

Biological methods: It includes the make use of a plant of vegetation cover.

(i) Agronomic practices: It includes natural protection of growing vegetation in a   mode that reduces soil loss. These are:

        (a) Contour farming: In which preparation of fields with alternate furrows & ridges to reduce water flow. Ridges at the same level are called as a contour. On slopes, however, this kind of farming is coupled with terracing.

(b) Mulching: It is effective against the wind as well as water erosion. Some, such plants as maize stalks, cotton stalks and etc., are used as a ‘mulch’. Mulches reduce soil moisture evaporation & increase amount of soil moisture by addition of organic matter to the soil.

      (c) Crop rotation: It decreases soil loss & preserves the productivity of the land.

(d) Strip cropping: It involves the planting of the crop in rows or strips to verify the flow of water.

    (ii) Agrostological methods: Grasses such as Cynodon dactylon are used as erosion resisting stabilizer plants. They are developed in strips between the crops. Such methods contain:

(a) Hay farming: This aims to grow grass in rotation with the field crops, which helps in building up the structure of soil, preventing soil erosion and improving its fertility.

(b) Retiring lands to grass: It involves growing grass on such lands where a major proportion of the topsoil has been eroded. Normally grasses are allowed to graze under suitable climate conditions.

Mechanical methods: These mechanical methods are used as supplements to biological methods.

• Basin listing: To construct a small basin along the slope to intercept & divert the runoff water.

(ii) Contour terracing: To construct a channel along the slope to intercept & divert the runoff water. This may be:

(a) Channel terrace: To dig channels at suitable intervals & the excavated soil deposited as a wide, low, ridge along, the lower edge of the channel.

(b) Broad-based ridge terrace: To make ridge along both the sides of the channel.

(c) Bench terrace: To create a number of platforms along contours or suitable graded lines across the slope.

Other methods:

(i) Streambank protection: To develop vegetation alongside the river bank, to construct drains, concrete or stone Pitching, etc. for checking, cutting and carving ‘of riverbanks.

(ii) Afforestation: Trees as windbreaks are planted at 90° to the prevailing wind in the deserts which verify the velocity of the wind. They confirm the spread of sand dunes or desert conditions or blowing away from the fertile topsoil. Windbreaks may be planted in a number of rows.

Prevention of soil loss:

There are a number of other conservation practices which can be utilized by farmers. Any single conservation practice can considerably decrease soil erosion rates. Combining a number of soil conservation practices is often more efficient. The ideal goal would be to reach a soil loss rate of 6.7 tonnes/ha/year. This is around the rate at which soil can rejuvenate itself. Making sure there are always plants rising on the soil and that the soil is rich in organic matter are two key methods of prevention. Organic matter binds to soil particles together, which reduces Soil erosion. Organic matter in soil increased with crop rotation or by incorporating organic fertilizers. Crop rotation is effective at enhancing soil structure. There are also several methods used by farmers to reduce soil erosion. Mulching is one example. It involves spreading hay or straw over a field as an alternate for a cover crop.

Read: Soil Types and Suitable Crops.

Soil Conservation:

Soil Conservation is the process of protecting the soil against erosion or deterioration. It involves the activities that can be undertaken to make sure our soils are at their optimum quality and health. Soil Conservation is the avoidance of soil loss from erosion or reduced fertility caused by over usage, acidification, salinization or other chemical soil contamination.

Soil Conservation farming:

Soil Conservation farming occupies no-till farming, “green manures” & other soil-enhancing practices. Such farming methods effort to mimic the biology of barren lands. The result is less labor & lower costs that increase farmers’ profits. No-till farming and cover crops act as sinks for nitrogen & other nutrients. This increases the quantity of soil organic matter. Prevention of soil erosion is also known as conservation of soil.

Many different methods have been invented throughout the years with the aim of preserving the nutrient level of the soil and preventing erosion.

1. Contour Plowing – Originating in ancient Phoenicia, Contour Plowing occupy plowing grooves into the desired farmland, then planting the crop furrows in the grooves & following the contours. It’s very effective ways for farmland on slopes to prevent runoff improves crop yields.
2. Terrace Farming – Terracing is a process of carving multiple, flat leveled areas in the hills. Steps are formed by the terraces which are surrounded by a mud wall to prevent runoff & hold the soil nutrients in the beds. More usually found in lesser developed nations due to the difficulty of using mechanized farming equipment in the terraces.
3. Keyline Design – A more enhanced version of Contour Plowing, maximum water retention is achieved by attractive into account all the watershed properties when making the contour lines. The Keyline refers to a topographic element linked to water flow. This allows the water runoff to run straight into an existing water channel, and prevent soil erosion caused by the water.
4. Perimeter Runoff Control – This is the perform of planting trees, shrubs & ground cover around the perimeter of farmland which impedes surface flows and keeps nutrients in the farmed soil. Using the grass way is a specialized way of handling perimeter runoff that uses surface friction to channel & dissipates runoff.
5. Windbreaks – Rows of tall trees are used in dense patterns around the farmland & prevents wind erosion. Evergreen trees can give year-round protection, but deciduous trees can be adequate as long as the foliage is apparent during the seasons when the soil is bare.
6. Cover Crops/ Crop Rotation – Cover crops such as turnips & radishes are rotated with cash crops in order to blanket the soil all year round & produces green manure the replenishes nitrogen and other critical nutrients. Using cover crops also suppress weeds.
7. Soil Conservation Farming –These practices can be used to prevent erosion & even restore damaged soil and encourage plant growth. Eliminating the use of nitrogen fertilizer and fungicides can increase yields and protect crops from drought & flooding.

Various Ways to Conserve Soil:

The technique to conserve soil is very simple and requires implementation so as to decrease the dire environmental impacts.

1. Agricultural Soil Conservation:

Agricultural soil conservation involves the practices that can be used by farmers to support the health and quality of soils.

2. Refraining from the practice of till farming:

Without till farming, crops have the possibility to remain on the soil instead of being plowed under at the end of the cropping season. The advantage of this practice is that it keeps the soil anchored rather than leaving it naked and open to erosion because of the exposure to the physical forces of wind & water.

3. The practice of contour plowing:

Contour plowing engages planting crops following the contour of the landscape rather than planting crops in straight vertical rows. This orients crop furrows to follow the contour lines, thus dropping water runoff during rainstorms.

4. Practicing organic farming:

Organic farming is totally reliant on green manure, compost, biological pest control, and crop rotation to produce crops, livestock, and poultry.

Home Soil Conservation Methods:

Home soil conservation methods are techniques that can be utilized at home to preserve & improve soil quality.

1. Planting a rain garden:

Rain garden refers to a small and shallow depression in your yard that you can use to gather stormwater in order for you to grow some wetland crops. Rain gardens can prevent soil erosion and provides with an opportunity to grow your own plants.

2. Reduce impervious surfaces:

Impervious surfaces limit infiltration of water into the soil & promote the free flow of water. For this reason, surface runoff can gain higher speeds leading to erosion of lakeshores & stream banks. Use of paving stones is a good alternative to concrete slab as it allows the water to pass into the soil.

3. Contour Bunding and Bench Terracing:

Contour bunding & bench terracing are effective soil conservation techniques. Bunding protects land from water runoff, & bench terracing recycles organic matter from one terrace to the next.

Read: Agriculture Soil Testing, Garden Soil Testing Guide.

Four Methods that must be adopted for Conserving Soil:

1. Afforestation 2. Checking Overgrazing 3. Constructing Dams 4. Changing Agricultural Practices
2. Afforestation:

The best method to conserve soil is to increase the area under forests. Indiscriminate felling of trees should be stopped & efforts should be made to plant trees in new areas. A minimum area of forest land for the whole country that is considered healthy for soil & water conservation is between 20 to 25 percent, but it was raised to 33 percent in the second five-year plan; the proportion is 20 percent for the plains & 60 percent for hilly and mountainous regions.

2. Checking Overgrazing:

Overgrazing of forests and grasslands by animals, especially by goats & sheep, should be properly checked. Separate grazing grounds should be earmarked & fodder crops should be grown in larger quantities. Animals freely move about in the fields for grazing & spoil the soil by their hoof which leads to soil erosion. This must be avoided.

3. Constructing Dams:

Much of the soil erosion by river floods avoided by constructing dams across the rivers. This checks the speed of water & saves soil from erosion.

4. Changing Agricultural Practices:

We can save a lot of our expansive soil by bringing about certain changes in our agricultural practices. Some of the excellent changes suggested in this context are as under:

(i) Crop Rotation:

In many parts of India, a particular crop is sown in the similar field year after year. This practice takes away certain elements from the soil, making it infertile & exhausted rendering it unsuitable for that crop. Rotation of crops is the system in which a special crop is cultivated on a piece of land each year. This helps to conserve soil fertility as different crops make dissimilar demands on the soil. For example, potatoes need much potash, but wheat requires nitrate.

(ii) Strip Cropping:

Crops may be cultivated in exchange strips, parallel to one another. Some strips may be allowed to lie fallow while in others dissimilar crops may be sown example, grains, legumes, small tree crops, grass, etc. Various crops ripen at different times of the year & are harvested at intervals. This ensures that at no time of the year the entire area is left bare and exposed.

(iii) Use of Early Maturing Varieties:

Early maturing varieties of crops take less time to mature & thus put lesser pressure on the soil. In this way, it helps in reducing soil erosion.

(iv) Contour Ploughing:

If ploughing in done at right angles to the hill slope, following the natural contours of the hill, the ridges & furrows broke the flow of water down the hill This prevents too much soil loss as gullies are less likely to develop and also reduce run-off so that the plants receive more water.

Read: Turmeric Cultivation Information.

Last Updated: February 12, 2019