What is Soil Erosion?
Soil erosion is the wearing away of topsoil by natural forces such as wind and water and is applied through farming activities such as tillage. Soil erosion typically is caused by the lack of cover on the soil, which leads it being susceptible to erosional forces. The best way to minimize soil erosion is to have plenty of vegetation cover. The roots within the vegetation hold the soil in place preventing a majority of erosion from occurring.
What are the types of Erosion?
Wind erosion occurs by the movement of the wind across the surface of the soil creating detachment, movement, and removal of the soil. Soils that are particularly susceptible to wind erosion are dry sandy soils, while clay and loamy soils are not as prone to erosion. The lack of vegetation and crop residue is the main culprit behind areas that suffer from wind erosion.
Water erosion occurs by the movement of water across the surface of the soil creating detachment, movement, and removal of the soils. Water erosion happens during spring runoff and through the season during high precipitation events. Soils that are particularly susceptible to water erosion are soils that are clay and loamy. Soil that is on a steep incline magnifies erosion due to the higher velocity of the runoff water. As with wind erosion, a lack of vegetation to hold soil in place can greatly increase erosion rates in water flow paths. Examples of soil erosion caused by water are gully erosion, sheet erosion, and rill erosion.
Erosion caused by activities like tillage occurs with the movement of soil’s downslope causing soils to accumulate at the bottom of the slope. These areas are found in areas such as hills and ridges but could also occur where there is a steep gradient such as sides of ditches and drains or along field edges. The greater the gradient the more the soils are at risk for erosion.
Why is it important to reduce erosion?
Reducing soil erosion is important at both an environmental level and an infrastructure level. Environmentally soil erosion leads to excess nitrogen and phosphorus being introduced to our waterways degrading downstream water quality. High levels of phosphorus and nitrogen in the sediment have been linked to eutrophication in water bodies causing significant growth of algae and other aquatic plants. Eutrophication leads to lower oxygen levels causing harm to aquatic plants and animals. Sedimentation causes several problems for the watershed.
- Murky water prevents natural vegetation from growing
- Causes disruptions in the natural food chain
- Impacts on fish populations by clogging first gills reducing their ability growth and fertility
- Sediment in waterways can affect and alter the flow of water and reducing water depth negatively affecting fish and aquatic vegetation habitat.
One main reason to reduce erosion is the time it takes to replace soil that is a loss. “In a balanced ecosystem, where plants above and root below ground protect soil year-round, soil erodes at roughly the same rate as it is formed.” (Delonge and Stillerman 2020) With the loss of organic material and nutrients from the topsoil, there is also a loss of productivity, which creates the need for further inputs into the soil.
The impact on local infrastructure is a major problem. In areas with a lot of sedimentation, there is a strain on the drainage system. Sedimentation increase the need for a drain cleaner as a result puts strains on municipal and provincial resources needed to complete drain maintenance. Decreased drain efficiency means water sits long on the land increasing the likelihood of crop or yield loss with producers.
What Can We Do To Prevent Soil Erosion?
The single biggest action to prevent soil erosion is to have erodible soils be covered with vegetation. The root structures of plants help to keep the soil in place even in high winds and fast-moving water. An example of this is to plant cover crops. Cover crops increase infiltration of water into the soil, slows the velocity of runoff, and increases soil organic matter improving soil structure.
Grassed ways are another great way to prevent erosion that happens in drains and ditches that experience high flows. Grass prevents soil from being lost in the channel but also can filter out sediment from the catchment area. Grassed waters are easy to maintain, still can handle large flows of water, and allow farm machinery to cross.
Installing side inlets at the end of ditches that connect to the main municipal or provincial drains is an effective way to reduce sediment from reaching waterways and preventing gully erosion along the drain. Side inlets effectively slow down the water flow leaving the drain ditch by restricting the amount of water that can flow out the ditch while still allowing the drain to empty.
Changes in tillage practices also help in reducing soil erosion. Going to no-till or low till allows for the root structure within the plant to remain in the ground decrease the chances for erosion. Keeping grass around the edge of the field along the municipal/provincial drains makes sure that cultivation does not take place into a ditch. When cultivation takes place in ditches sides it leaves them open to slumping and erosion.
What We Are Doing At SRRWD To Address Soil Erosion?
SRRWD is implementing a field erosion control program. The objective of the program is to sustainably manage surface water to enhance water quality and water quantity by reducing downstream flooding and reducing erosion. The goal is to create erosion control areas through designing and implementing innovative, site-specific techniques to reduce the loss of topsoil from cultivated fields and prevent sediment deposits in waterways.
Examples of projects that would qualify in this program would be grassed waterways, grass field edge buffers, and the installation of side inlets.
These projects would also qualify under the Alternative Land Use Services Program where there would be an annual payment up to a maximum of $100 per acre for the planting of perennial grasses in erosion control projects.
Jeremie Lussier Grassed Waterway Project
In 2020 Jeremie Lussier who farms along the Marsh River in the RM of De Salaberry signed up to participate in the SRRWD Alternative Land Use Services. One of the project sites was located on a drain that flows into the Marsh River. Jeremie planted perennial grasses all along the drain. This quarter-mile stretch will now reduce soil erosion and siltation along this waterway. Jeremie says participating in a program like this is great for his operation as it minimizes the risk of planting crops in an area that is prone to flooding in high flow events. While at the same time, he can contribute back to the community at large through the environmental benefits of the project such as nutrient and sediment reduction in our waterways.
Delonge and Stillerman, 2020. Eroding the Future: How Soil Loss Threatens Farming and Our Food Supply. (https://www.ucsusa.org/resources/eroding-future)
Interested in participating in the Erosion Control Program click here to: Apply Now