Soil erosion is a problem that is seen on every continent, in every country and on any type of soil and environment. Erosion is natural process but with our activities changing natural dynamics and removing vegetation cover, soil erosion has been steadily accelerating over the last decades.
For example, when forests are clear cut and land is transformed into croplands, the rate of soil loss increases by 52 percent . The Food and Agriculture Organization (FAO) estimates that arable lands worldwide lose every year 75 billion tons of soil due to erosion . Such a high rate of soil loss renders croplands infertile, in need of constant fertilization with synthetic substances, or even results in a complete land abandonment due to the severe degradation. Scientists estimate that, globally, 10 million hectares of arable land are abandoned every year for this reason .
This not only undermines our ability to produce enough food in the future, but also destroys biodiversity and ecosystem services that were once in place but cannot be supported by the lifeless ‘dirt’ which remained behind.
Soil erosion causes other problems as well. For example, sedimentation and nutrient loading in waterways, and an increased risk of flooding and landslides as result of soil removal.
So how can we prevent erosion from happening in your yard, on agricultural or public lands? The following are methods that have proven to dramatically reduce and prevent erosion from occurring in the first place, regardless whether you are focused on preventing erosion in your yard or on a larger piece of land that is used to grow crops. These measures are effective in many situations.
Factors responsible for soil erosion
When erosion takes place, soil particles get loosen by the impact of water, ice, wind or gravitational pull and can be easily carried away by the repeated action of these forces. The vulnerability of soils to be damaged differs, but in general is affected by the combination of factors that are responsible for erosion.
These factors are linked to local :
Long-term weather patterns in an area affect soil stability. Heavy spring rains, strong winds, turbulent storms, or long summer droughts that destroy vegetation and are followed by floods disturb uncovered soils and may initiate the process of erosion.
The duration and intensity of rainfall in an area create erosive forces of water on land surface. More it rains and heavier the rain is, more surface runoff happens, triggering water erosion. Runoff causes usually the biggest problems on agricultural lands, carrying nutrients and organic matter away from croplands, making it harder to maintain soil fertility to grow crops. How heavy surface runoff can get is also determined by the slope of the land and the drainage characteristics of soils (e.g. how well does water infiltrate into the soil).
- Soil characteristics
Some soil types are more likely to subdue to erosion than other. Soil texture depends on the size and distribution of soil particles. Many soils are a combination of sand, clay and silt, so their erodibility depends on the most prevalent particle type.
Sandy soils contain larger particles that do not stick well together and get easily detached from each other by water or wind. Clay, on the other hand, consists of fine particles that stick together closely. Clay soils are not so porous and are resistant to wind erosion, but because of their structure that doesn’t allow water to easily infiltrate, water tends to sit on the top, drowning vegetation and creating muddy flow that washes soils off.
High organic matter content in soils is excellent in preventing soil damage. It absorbs rainwater nicely and has the capacity to control water saturation of soils. When it rains, soil organic matter stores just enough water to maintain moisture for plants until the next rain, while letting all excessive water pass through. Organic material is also a vital part of healthy soil structure—encouraging the formation of aggregates that bind particles together and support porosity—factors that help prevent soil degradation by erosion .
Different natural or man-made features in the landscape influence where erosion takes place with greater intensity. For example, on exposed slopes that have been deforested the rate of erosion increases when compared to a flat grassy area just a couple miles away. Some slopes are naturally too steep to support vegetation and are prone to erosion at any time. They may pose a constant risk to human infrastructure nearby.
In other cases, our land use management exacerbates the problem of unstable soils. For example, maize rows oriented down the sloping field only encourage creation of rills when it rains, as water rushes downhill unobstructed. If rows were oriented along the contour, maize plants would help to slow down and disperse the running water. Thus, protect soils better.
River banks and coastlines are extremely prone areas to erosive forces of moving water. In fact, they are being constantly eroded by the impact of water. The rate of erosion depends on the force of water and the type of soil or rock that creates the boundaries between water and land.
Rock types and their mineral composition are closely linked with the soil texture and the size of soil particles in an area. In hilly regions or along coastlines, geology of cliffs and rocks affects their erosion rate over the time. Hard rocks like granite get worn down by weather much slower than soft sandstone which keeps changing relatively fast.
- Vegetation cover
Vegetation cover, its thickness and biodiversity of plant species, is extremely important in protecting soils. Plant roots hold soil particles in place, leaves and plant bodies slow down rain and wind impact. Plants also encourage water uptake by soils, therefore reducing runoff. Plants create a protective shield even during winter when snow lies on the ground. Their roots prevent damage to upper soil layers when snow melts and runs into the nearest streams. It is a common occurrence that erosion accelerates when natural perennial vegetation gets stripped away to make space for agriculture or development projects.
- Socio-economic development
The management of natural resources depends on the socio-economic situation and development trends in an area. In some countries, intensive agriculture may be the main cause of erosion. In other regions, it could be overgrazing, deforestation (especially illegal logging), urbanization or mining.
Land use management affects soil health and our ability of protecting soils from degradation, but the way we manage land differ greatly across the regions and throughout the world. It is possible to see positive soil conservation practices in one area and then harmful activities right across the road.
Simple ways how you can prevent and control soil erosion
Whether it is in your backyard, on agricultural land or in a distant corner of your garden, soil erosion can turn to a serious problem if left to progress beyond control. Besides that, fixing severely eroded land and repairing the damage done by displaced soil costs significant amount of money.
You should consider that eroded lands lose their value as well. According to calculations of the Iowa State University, the value of eroded lands drops by three to seven percent for the whole land, even when erosion affects only a relatively small part. This means that you may be losing on your long-term investment if you let erosion progress, because you will not be able to sell the land for the full price.
It is in your best interest to try to prevent the development of soil erosion and reduce existing soil loss as soon as possible. Your land, your wallet and future generations will certainly benefit from your early action.
Here are some effective measures that will help you to control soil erosion on your land.
#1 Planting permanent vegetation
One of the best ways that we can prevent erosion is to plant vegetation with deep roots that help to hold the soil in place. This is especially important in areas that are more vulnerable to erosion, such as along rivers, streams, and on hillsides. According to data from the Iowa State University, permanent vegetation cover reduces soil loss by more than 50 percent (in some cases the success rate is 100 percent) and surface runoff by 30 percent on average .
The best plants for erosion control are native plants with deep roots, such as native prairie grasses like blue wildrye or purple needle grass, wildflowers, and woody perennials, like trees and shrubs. Typical lawn grasses tend to have very short roots, and therefore do not protect slopes from erosion nearly as well as native and woody perennial plants.
When deciding which plants are the best to control erosion on your property, make sure you base your selection according to the specific characteristics of your site. If the location is dry, select drought resistant species because you do not want to have to water the plants—pouring water over soil would not help in tackling erosion. For slopes, look for trees and shrubs with strong root system that do not grow very tall. If you are aiming to reduce surface runoff and water accumulation in some low-lying spots, think of grasses and trees that do well in wet conditions. They will absorb excessive soil moisture and release it into the atmosphere through their leaves, decreasing oversaturation of soils.
One great tree species for this purpose are willows. Willow trees grow fast, and their roots create a strong binding network underneath the soil. These trees like humid conditions and tolerate even soils with higher salt concentration. Furthermore, willows are known for being effective in phytoremediation of soils, removing pollutants from soils and incorporating them into their biomass. These trees can perform many great functions for creating a healthy environment if you plant them in the right location.
Permanent vegetation doesn’t have to be planted across your whole land if you are planning on leaving some parts for gardening or crop cultivation. Planting stripes of permanent cover with native grasses or creating shrub and tree barriers helps prevent erosion as well . You can create nicely diverse landscape that will yield you more produce, will mitigate erosion and will be interesting to look at. You can get inspired from sustainable agroforestry practices. For example, agroforestry farmers achieve great results when planting trees along contours.
#2 No-till farming and gardening
By using no-till farming methods and the minimum disturbance, the delicate structure of the soil can be protected and erosion is significantly reduced compared to tillage cultivation. According to FAO, the rate of erosion on soils that are not tilled is 90 percent lower than on the conventionally tilled soils.
When soils are tilled, soil aggregates are broken down and healthy soil structure is disrupted. Crop residues and any other vegetation are removed from the surface, leaving detached soil particles fully exposed to rain and wind. Disturbed soil structure results in loss of porosity, which is crucial for water infiltration. This results in increased surface runoff that only encourages further erosion. Other negative effect is the loss of nutrients and organic matter when soils are turn and the land is left barren and exposed to the elements for prolonged time period between planting.
If you choose to leave your soils undisturbed, you will protect the soil structure and preserve protective vegetation layer. You will also maximize their biological activity by allowing soil microorganisms flourish and feed on organic residues that you left in the soil. This will enhance healthy nutrient cycles and improve soil health. These are the key processes that ensure optimum capacity of soils to absorb water, minimize runoff and withstand extreme events without getting damaged.
#3 Protecting soils with cover crops
As the name suggests, cover crops provide a protective cover for soils in between the main plantings. Their function is the same as the function of permanent vegetation. They protect soils from rain and wind, slow down runoff and encourage water infiltration.
It is recommended to plant cover crops after the harvest of the main crop. Take for example corn. Once you harvest corn, the land will most likely remain barren over the winter. This means that the soil will lack the protective layer of growing vegetation in the season when it rains or snows a lot and the land is subjected to cycles of freezing and unfreezing. This easily damages soil structure and increases the risk of soil loss.
That is when cover crops, such as rye, barley, lentil, mustard or clover, come with numerous benefits. Studies have shown that cover crops reduce soil loss by 30 to 100 percent when compared to fields without any cover . Erosion on lands with mustard cover crops reaches, for example, maximum 20 percent throughout the season . However, you should know that most of the commonly used cover crops have shallower roots that do not stabilize soils on slopes as effectively as native grasses would .
Cover crops not only hold soils in place when crops are not grown, they also prevent weed growth in planting beds outside the growing season and help enrich the soil with nitrogen (through the use of leguminous plants such as clovers).
If none of the options listed above suits your needs, you have another alternative that doesn’t require planting of other plants or crops on your land and allows you to create a clean look to your property. You can protect the soil by covering exposed spots around the plants with a mulching material. By putting down mulch, you are keeping bare soil from being washed and eroded away, as well as helping to retain soil moisture and eliminate weed growth around your carefully selected plants. Mulching layer stabilizes soil temperature, protecting plants and soil from the effects of fluctuating temperature in winter.
Commonly used wood chip or wood bark mulch is often applied in landscapes and gardens, around trees or bushes. This type of mulch is popular for the nice, clean look it provides. Organic mulches, that keep decomposing faster, like shredded leaves and straw, are mainly applied to protect and nourish your garden soil of organic material in the fall and in the spring.
You can use mulch even on mild slopes. However, on steeper slopes, loose wood chips or straw mulch may be carried down by runoff too fast. In such a scenario, you may want to try erosion control blankets made from straw, where straw is bound by a synthetic plastic or natural jute netting into a blanket that is evenly laid on the ground. These blankets still perform the protective function, but do not get easily washed or blown off. The next point lists more about them.
#5 Soil erosion control blankets and fiber rolls
If you have been wondering how to stop erosion on a steep hill, soil erosion blankets could be the best solution. They are designed to slow down surface water and prevent erosion on barren slopes after construction activities or during landscape rehabilitation. By providing a stable layer of soil protection, erosion control matting is efficient even on steeper slopes .
These erosion prevention agents are made with synthetic materials, such as polypropylene, or with natural materials, such as straw, coconut fiber, wood fibers, or jute that are bound together by a natural or synthetic UV-degradable netting.
Many erosion control blankets are made from permeable, biodegradable materials that do not harm wildlife and allow for water infiltration and growth of vegetation. However, this also means that they last for a limited amount of time and their use is a temporary solution. For example, straw blankets last around three months and are often used to stabilize slope before permanent vegetation grows strong enough to substitute for their function. Jute mats last slightly longer–on average half a year.
For longer term solutions, you can find slow degrading options made of synthetic and natural fibers. These blankets should last up to three years .
As a substitute for soil erosion control blankets are in some cases used other temporary erosion control measures like fiber rolls (rolls made from straw, rice wattle, coconut fibers, etc.), hay bales, logs, and silt fences. Their function is to trap sediments and slow down water from moving downhill by creating horizontal barriers across the slope. This helps reduce the amount of soil carried away and improves water retention, which in turn creates favorable conditions for emerging vegetation. Once the slope is stabilized through the establishment of permanent vegetation, these barriers are removed.
#6 Terracing with retaining walls & edging
Imagine all those beautiful terracing rice fields that are so characteristic for the rural landscapes of Asia. Terraces have been effectively used to cultivate crops in hilly areas for the last 5,000 years . Farmers have been building terraces to grow crop in easily erodible terrain. Instead of farming on a slope from where nutrients and water easily disappear, they have been breaking down the slope into a series of horizontal plots for cultivation.
The purpose of retaining walls with terraces is to create a barrier that holds the soil in place and prevents water runoff that would otherwise carry sediments down the slope after every rain. Terraces are efficient in retaining water, giving it time to infiltrate into the soil. They improve water drainage on your land as well. According to your design, retaining walls may channel excessive water where it’s needed.
Whether on a large scale, like rice fields, or on a smaller scale in your backyard, terracing allows cultivation and erosion control of many difficult slopes that would otherwise be unsuitable for any activity. With the structural support of retaining walls, terraces can create a nice decorative element on your property, giving it a new look. They can be useful for the creation of raised garden beds that are for many gardeners more comfortable to maintain.
One permaculture farmer named Sepp Holzer has had a very successful ecologically-based farm for many years in the mountainous region of Austria through the use of terraces on steep slopes.
Watch this educational video about Holzer’s farm:
On less steep slopes, extensive measure like building a retaining wall is not necessary. Subtle edging may be enough in performing the same function as retaining walls. You can select natural edging materials such as bricks or small stones to prevent erosion of soil from a garden bed or within a landscape, or you can just create a little edge with a spade and keep maintaining it whenever is needed.
#7 Riprap, stabilizing soil with stones and boulders
Riprap is a permanent placement of larger rocks on less steep slopes, banks of rivers and lakes in an area of strong runoff. The main purpose of creating a rocky surface is to cover the soil and stabilize it, while slowing down water velocity. That is why you can see this solution often employed in places where water constantly keeps eroding soil away–like along waterfronts. Large rocks have also proven useful for stabilizing storm drainage ways.
The main advantage of ripraps is their durability. Once in place, rocks perform their protective function for a long time without the need of much maintenance–if installed properly. It is only important to realize that riprap is not the best solution for steeper slopes, as rocks could get easily displaced over the time and cause bigger damage to the soil and infrastructure below. Additional risk comes when the size of rocks is not chosen accordingly. Too small rocks for the slope angle and pressure of water are also unstable in the long term.
#8 Controlling water flow across your land
If you have a persistent problem of soil erosion in some parts of your property, you should consider adopting measures that would divert rainwater and control its flow across your land. You have a few possibilities.
You can create neatly looking dry creeks that direct water away from your land or channel runoff to your designated area from where you can reuse it (e.g. for irrigation). Dry creeks look like a small version of a rocky river bed and even imitate its function. You also have an option to plant vegetated filter strips or simply install drainage pipes to gather water and carry it away from critical areas. Some people choose to protect land around their houses by implementing so called French drains. French drains are trenches along outer house walls that contain drainage pipes covered by permeable gravel.
If you have a problem with strong water runoff flushing over your backyard but cannot control the area from where the runoff originates, like for example having a hill owned by someone else right behind your property, you could also build a berm to minimize water damage across your land. Berm is a little artificially created hill where you can plant decorative plants or native grasses and shrubs. By raising the ground, you change the natural channel of water. Water will have to pass around rather than making its way directly through the middle of your backyard.
On agricultural lands, especially in hilly regions, farmers get good results by building series of contour trenches and swales that help to catch and accumulate runoff water. This ensures that water remains longer available for crops as it is gradually taken up by soil. Trenches and swales greatly help to stop erosive processes on cultivated lands.
As a farmer you can make the most of water passing through your property by creating a retaining pond for rainwater harvesting or imitating natural wetland habitat in place where water tends to accumulate. If you have such possibility and your land has a spot like that, this measure may help prevent erosion in surrounding areas because you will intentionally direct water flow to one place and prevent it from running across other parts. Accumulated rainwater can be used later when droughts hit the area for crop irrigation .
#9 Contour farming and gardening & strip cropping
Growing crops on slopes can be particularly challenging and plowing on slopes can easily lead to soil erosion. However, there are several techniques for cultivating crops on slopes that prevent erosion. These include contour farming, where farmers plow and plant across a slope along its contour lines as opposed to planting in downhill facing lines.
By following the natural contour lines, we can prevent erosion by up to 50 percent . And not only that. This practice greatly reduces the loss of nutrients from cultivated soils. In drier areas where farmers are dependent upon rainfed agriculture, contour cropping delivers higher yields because it retains rainwater more effectively .
Strip cropping is a practice that boosts these positive effects of contour farming in hilly regions even more. It is especially effective on steeper slopes where improved water retention is the key to addressing soil erosion. Strip cropping is usually done by planting different crops in alternating strips, which are regularly rotated to allow soil regeneration and nutrient replenishment.
For example, farmers grow rows of leguminous cover crops like clover in between corn strips. In more extreme conditions where maintenance of soil fertility may be difficult due to the climate and steepness, crops are grown among permanent vegetation strips, like trees or hedgerows. Permanent vegetation stabilizes soil better and creates positive microclimate for crops in between.
#10 Preventing soil disturbance by livestock
Overgrazing and land disturbance caused by keeping too many animals in one area for too long period of time is one of the most common causes of soil erosion, eventually leading even to severe land degradation.
Land that is used for livestock grazing is often hilly or is located in marginal areas that are unsuitable for crop cultivation. Unsustainable livestock management on such lands leads to overgrazing and decreases the protective groundcover. When more than 60 percent of vegetation gets removed, the rate of erosion accelerates, and topsoil is more likely to be washed off with every rainfall event .
Other negative effect of livestock overgrazing is soil compaction in areas where animals gather, which further disables vegetation emergence and maintenance of soil structure. When these factors add up, they significantly contribute to soil erosion by wind and rain. According to a study on the impacts of overgrazing on soil erosion in Mediterranean, erosion increases by 5 to 41 times in overgrazed areas .
The key to preserving soils on grazed lands is to respect the natural capacity of the land and vegetation to support the number of animals we intend to keep on the property. Vegetation should have enough time to recover. Areas exposed to more stress, such as creeks, drinking and feeding areas, shelters, need to be managed accordingly. For example, moving feeders or waterers couple feet away while fencing off previous location and seeding a new grass mix to recover vegetation during the rest period.
The use of sustainable grazing and pasture management techniques like for example rotational grazing that allows enough time for vegetation regeneration and soil rest, reduces the risk of exhausting pastures. In fact, science-based sustainable grazing practices are even being used to restore various degraded landscapes in some parts of the world.
#11 Afforestation and sustainable management of marginal areas
When talking about soil erosion control measures, we should not neglect the areas that have already been damaged but have a potential for great improvement when managed properly. Restoration of degraded ecosystems and protection of marginal areas to ensure that we will place sufficient soil erosion prevention methods in place is crucial.
Afforestation is one of the most effective long-term solutions. Planting trees goes a long way in preserving soil and ecosystem health. Besides stabilizing soils with their root network, trees are especially helpful in mitigating erosion caused by water runoff. This is thanks to their ability to control water regime in an area.
Tree foliage slows down rain drops before they even reach the ground. Through their canopy, trees also reduce the amount of rainwater that reaches the ground. When it rains, tree canopy captures approximately 30 percent of rainwater and another 30 percent are soon after the rain drawn from the soil by tree roots .
But that’s not all. Trees go even further in protecting soils. You may have noticed this yourself. Forest floor usually contains a rich layer of decaying leaves and needles. This layer is a natural mulch with a great capacity of absorbing water. According to scientists, water holding capacity of tree litter is up to five times its weight . This means that afforestation can be a great and cheap solution that can help with oversaturation and drainage problems on some lands—especially lands that are prone to flooding.
Trees can perform truly impressive functions when it comes to creating a stable environment that promotes healthy soils and balanced water cycle. We should remember that they are our best allies in tackling soil erosion in many places around the world.