SOIL EROSION

Erosion degrades soil quality and is one of the main reasons for the loss of agricultural land in the world. Understanding the causes that lead to soil erosion and its mechanisms will stop the destruction of the fields. The effects of erosion can be very serious, but prevention and reduction measures, as well as early detection of the problem, mitigate the risks. Satellite technology for remote crop monitoring can help in this regard, as soil erosion correlates with the level of vegetation in a fiel

What is Soil Erosion?

The concept of soil erosion refers to the deterioration of the land due to the elimination of its particles. The basic stages of soil erosion are 3:  detachment, transport and sedimentation . Its speed depends on the  type of soil , the aggregation, the infiltration and the ground cover. For example, well-aggregated fields are less vulnerable, and bare fields are the easiest to destroy. Slopes require additional protection against water erosion during rain, which can be addressed with cover crops, perennial grasses, or terracing.

Factors Causing Soil Erosion

There are natural and anthropogenic erosion factors. The soil in the fields is blown by the wind or rapid water runoff during heavy rains. But there is also soil erosion caused by agriculture itself when poorly managed.

Natural Soil Erosion Factors

• Strong gusts of wind . Strong winds stir up tiny particles of dry land, which is a typical problem in semi-arid regions and leads to desertification.
• Climate change . Abnormally intense rains or temperature jumps destroy the surface of the field. Another effect of climate change on soil erosion is the retardation of vegetation growth, which reduces field cover and exposes it to rain and wind.
• Rains and floods . Heavy rains wash away the topsoil particles, while large raindrops hit the surface of the field, deforming it. Air currents during floods are another cause of soil erosion.
• Forest fires.  Trees and shrubs slow down water runoff. When forests or buffer zones are destroyed by forest fires, streams find no obstacles in their path.

Soil Erosion Caused By Man

Apart from natural factors, there is also man-made soil erosion, due to irresponsible farm management or deforestation for urban expansion, tourism development, road construction, etc.

Agricultural Practices That Cause Soil Erosion

Natural vegetation protects much better than crops, because farmland is more vulnerable to rain and wind. In addition, agricultural practices can lead to soil erosion due to reduced biodiversity, both in the variety of vegetation and in soil microorganisms. In turn, the lack of organic matter and beneficial biota has a negative impact on the fertility of the fields because it  not only takes away the soil particles, but also the nutrients from the bare fields.

The main causes of soil erosion due to poor farm management are excessive fertilization or irrigation, conventional tillage, monoculture, overgrazing, etc. Let’s see the impact of the different agricultural practices in the erosive processes.

Does monoculture cause soil erosion?  Monoculture involves growing the same plant for several seasons. Since each crop requires certain nutrients, this practice causes the depletion of the fields. Consequently, it can lead to land degradation and increased soil erosion.

Can conventional tillage cause soil erosion?  Yes. Specifically, the moldboard plow loosens the soil, contributing to the erosion of agricultural soil by water and wind. By contrast,  no-till agriculture  avoids these processes.

Do fertilizers cause soil erosion?  It can happen. Excessive use of mineral fertilizers under insufficient organic fertilization causes dehumidification and destruction of its structure, which in turn makes it more vulnerable to erosive processes.

Does irrigation cause soil erosion?  Sometimes yes. Artificial irrigation is the only way to grow crops when there is no natural water supply, but over-irrigation can cause topsoil erosion. It is mainly about surface irrigation, when nutrients and particles of the upper layer of the soil are detached in the irregular fields due to the effect of gravity.

Does overgrazing cause soil erosion?  Yes. Overgrazing is a clear example of mismanagement  of pastures , it destroys the vegetation cover and favors erosive processes. Rotational grazing and cover crops can solve this problem.

Does terraced farming cause soil erosion?  No. On the contrary,  terraced farming  prevents erosion by slowing down water currents on smooth platforms.

Soil Erosion Caused By Logging And Deforestation

Any felling of trees can speed up the erosion process, be it harvesting wood or expanding agricultural land for oil palm cultivation. The practice of clear felling, when all or most of the trees are removed, is the practice that most exposes forest land, thus causing soil erosion through desertification.

Types of Soil Erosion

The classification is based on the speed of the erosion process or its cause (agent). Thus, there are different types of soil erosion. The main agents of soil erosion naturally are water currents and wind storms, although the situation can also be aggravated by human activities.

water erosion

As its name suggests, this type of soil erosion is caused by water and involves the removal of the top layer of soil after rains, snowmelt, floods, or poorly managed irrigation. Therefore, it can be produced by both extreme weather events and agricultural activities. On bare land and in the event of heavy rain or snowmelt, destruction by water occurs more quickly.

The most common forms of soil erosion by water are banks, sheets, gullies, and splashes. Consult its detailed description in our section “ Water erosion: Types, causes, effects and prevention ”.

Wind Erosion

Another factor that causes soil erosion is dust storms that destroy the top layer of soil. Dust storms have been a frequent phenomenon in recent decades, especially in arid places. The erodibility increases if the soil is uniform, fine and dry. On the contrary, the ridges reduce the energy of the wind and the heavy and rough particles are more difficult to remove.

temperature erosion

This variant occurs with situations that depend on temperature and climate, such as cold, heat or sunlight. A higher temperature causes the rocks to expand, while with the cold the rocks contract and freeze. These temperature changes cause cracks, leading to potential erosion of soil and rock.

Gravity Erosion

It happens because of gravity. Rocks, stones, and loose soil tend to accumulate in low areas, such as valleys.

anthropogenic erosion

Anthropogenic soil erosion occurs due to anthropogenic factors and human activities that can affect soil erosion directly and indirectly. For example, a direct impact comes from mining and quarrying. The indirect consequences derive from unsustainable management, which disturbs the upper layer of the soil and increases the erodibility of fields and forest masses.

Consequences Of Soil Erosion

The erosion process affects agricultural productivity, worsening the standard of living and well-being of rural communities (both individual farmers and  agricultural cooperatives ). Over time, eroded farmland loses  soil fertility , degrades, and becomes unsuitable for agricultural activity.

In addition, erosive processes drastically damage nature, reducing biodiversity and causing an imbalance in the ecosystem. Soil erosion problems do not end there. Often it goes unnoticed and the deterioration becomes irreparable.

Effects Of Soil Erosion On Agriculture

Erosion progresses differently in each field and the time it takes is also different. Erosive processes on farms can proceed slowly, but they can be accelerated due to weather phenomena or field treatment. In particular, salinization of fields or compaction due to the movement of heavy machinery or overgrazing worsens water infiltration and accelerates the rate of erosion.

Over time, eroded fields degrade and become unsuitable for agricultural activities. This occurs due to the negative effects of soil erosion, such as depletion of the topsoil, planting material, water pollution, field acidification, etc.

Topsoil Loss

The top layer is the richest in organic matter and nutrients, so its removal by water or wind essentially worsens the fertility of the field, which is a critical effect of agricultural soil erosion. In addition, hollows and ravines considerably complicate cultivation of eroded land.

Soil Acidification

Lack of organic matter can increase field acidity, slowing crop development and exposing farmland to water and wind.

Loss of planting material

Flowing water or dust storms wash seeds from fields and destroy seedlings, causing crop losses and diminishing farmers’ profits.

Water contamination

Other consequences of soil erosion are sedimentation and contamination of water bodies with chemical substances from the fields, which, in turn, deteriorates the quality of irrigation water.

Environmental Impact of Soil Erosion

The negative consequences of soil erosion do not only affect agriculture. Some examples of the damage caused by soil erosion are the deterioration of aquatic fauna and flora, the loss of biodiversity, sedimentation and frequent flooding.

Frequent floods

When forests are converted to pasture or fields, there is always a risk of frequent flooding because tree roots fix the ground. As these zones lose their infiltration properties, this also contributes to flooding and waterlogging.

Clogged Waterways And Contaminated Waters

Long-term effects of soil erosion include clogging of waterways and sedimentation. In addition, the eroded particles not only cause sedimentation in the most affected areas, but also clog water courses with grass, dams and water pumps. Runoff from the fields often contains chemicals that are dangerous to people and animals and poison drinking water.

Biodiversity loss

Eroded lands have sparse vegetation and become completely bare over time. This means not only the decline of the local flora, but also of the fauna, since many organisms are deprived of their natural habitats. The loss of biodiversity causes an imbalance in the ecosystem.

Greenhouse Gas Sequestration Reduction

Vegetation and trees are great carbon dioxide storers, but eroded land can barely support their growth. In addition, soils can also act as  CO2 sinks on their own . According to Professor Peter Smith of the University of Aberdeen, the earth can retain about 5% of anthropogenic greenhouse gases per year. Sustainable management could improve the situation and stop the loss of vegetation that stores carbon on our planet.

Soil Erosion Solutions

Decision-making in the control of soil erosion depends on factors such as the type of soil, topography or climatic characteristics, as well as the agricultural practices applied, such as the tillage system or crop rotation. It is important to analyze the effectiveness of the applied methods and adjust them to each field.

Success begins with early detection of the problem and choosing the appropriate methods based on its severity. For example, replanting,  cover crops  , or mulching can be good ways to reduce soil erosion in the early stages, as vegetation protects fields from runoff, raindrops, and wind. In severe cases, the impact of soil erosion can be mitigated with terracing or check dikes.

Other soil erosion control measures include contour cropping and planting perennials with strong root systems to fix the soil and stem runoff.

How Can Soil Erosion Be Prevented?

It is not so easy to reduce erosive processes and even more difficult to stop them, which is why prevention is by far the best control method.

Farm On Suitable Land

Some land is extremely prone to erosion, so it cannot be used for agriculture without certain preventive measures to mitigate the risks. In addition, each type of terrain requires specific management to protect the soil from erosion.

Practice Terrace And Contour Cultivation

Since erosion develops rapidly due to runoff, terrace farming is the only effective way to farm on steep hills. Contour farming decreases soil erosion because plants absorb water and furrows prevent it from flowing, mitigating the risk of destruction. Plants with strong roots also anchor the soil and prevent water from flowing down the slope.

Don’t Leave The Ground Bare

Covering the ground not only helps to reduce, but to prevent the destruction of the land. More than 30%  soil cover in erosion control helps mitigate risks. Full cover can be practiced in most grazing and crop production systems.

plant vegetation

Planting crops helps prevent soil erosion by ensuring continuous soil coverage, while leaving the field bare favors erosive processes. Provide a hedge between growing seasons with crop rotation practices and cover crops. In addition, crop rotation favors a reduction in soil erosion by fixing the soil with alternately planted deep-rooted crops. In addition, the sequences of tall vegetation protect the fields from the wind.

Use Mulch

Straw, dry grass or textile mulches not only protect the field from rain and wind, but also retain soil moisture, which protects the soil from cracking. In addition, decomposed mulches of biological origin add nutrients and organic matter to the field, boosting fertility and improving its structure.

Switch To No Till Or Minimum Till

Plowing is a common practice in conventional agriculture, but studies show that reducing  disturbance to farmland  with a no-till approach can help reduce soil erosion as well. When the soil aggregates and the vegetation cover remain almost intact, the erosive processes develop more slowly.

Add Organic Matter

A healthy topsoil should contain organic matter from rotted animal and plant manure. Organic matter prevents soil erosion in several ways:

• supplies vital nutrients to crops, making the ground cover more vigorous;
• improves water retention properties and reduces runoff;
• It compacts soil particles to help it resist currents and winds.

Embrace Rotational Grazing

When cattle graze in the same place for a long time, almost all the vegetation is eaten. In turn, the loss of vegetation cover often causes erosion. That is why it is important to let the grazed areas regenerate by moving the cattle to other pastures.

Switch to Drip Irrigation

Since dripping excludes excessive water flows and splashing, it is the best irrigation method to prevent soil erosion. Drip systems deliver tiny droplets of water to plant roots above or below ground without risk of destruction.

There are different ways to reduce soil erosion, depending on its type and the characteristics of the field. It is normally recommended to use conservation agriculture techniques and sustainable agricultural practices. Through the application of modern technology, farmers can enhance the effect of less invasive tillage. As for soil erosion, remote sensing tools are excellent for monitoring large agricultural areas and can be used by both the “big guys” in the agricultural sector and small farmers.

Variable Rate Fertilizer Application

As previously explained, the inappropriate use of certain agrochemical products can facilitate wind and/or water erosion. Soil erosion on farmland often occurs due to excessive mineral fertilization in the absence of adequate amounts of organic fertilizers. This approach leads to the dehumidification of the field and the destruction of its structure. Fields with low humus content are more susceptible to soil erosion, as small, unattached soil particles are more easily washed away by water or blown by wind. However, these negative consequences can be avoided with a rational distribution of mineral and organic fertilizers, facilitated by variable rate application technology.

Excessive use of mineral fertilizers causes leaching of nutrients from the soil profile, chemical contamination, crop poisoning, and decreased field productivity. On the other hand, rational application will not only save farmers costs by reducing the amounts of resources needed, but will positively affect the environment, also helping to control soil erosion.

Crop Rotation Planning And Monitoring

Crop rotation is one of the key agricultural practices to reduce soil erosion. Depending on the steepness of the slope and other existing manifestations of erosion, one or another type of crop rotation is applied, including vegetative control of soil erosion with perennial grasses. Furthermore, crop rotation is considered an important factor in maintaining high field productivity, since constant cultivation of the same monoculture depletes the field, leading to disease and soil toxicity.

By comparing productivity maps from different periods, farmers can also  track changes in vegetation level across the entire field or in their individual zones.  Soil erosion mechanisms are one of the reasons for the decrease in the level of vegetation. Once a change is detected, it makes sense to inspect the field and perform soil tests, to understand the cause of the deterioration and to confirm or exclude soil degradation by erosion as part of the crop productivity problem.

The Importance of Soil Erosion Control

Eroded fields decrease the productivity of the entire agricultural sector in the US and the rest of the world, and it is important to know areas of soil erosion early before the damage is serious. Most producers have managed to slow down the destructive processes of the soil on their farms, but the problem remains one of the main reasons for the loss of arable land on our planet. Therefore, farmers need to know what causes soil erosion and how to stop it in time.