Water and Wind Erosion

The impact of soil erosion on water quality becomes significant, particularly as soil surface runoff. Sediment production and soil erosion are closely related. Therefore, the most effective way to minimize sediment production is the stabilization of the sediment source by controlling erosion. Several conservation practices can be used to control erosion but first, you need to understand the factors affecting soil erosion. Soil erosion is the detachment and movement of soil particles from the point of origination through the action of water or wind. Thus, minimizing the impact of water or wind forces is the main objective of erosion control.

Soil erosion by water occurs when bare-sloped soil surface is exposed to rainfall, and the rainfall intensity exceeds the rate of soil intake, or infiltration rate, leading to soil-surface runoff. Soil erosion can occur in two stages:

1. Detachment of soil particles by raindrop impact, splash, or flowing water; and
2. Transport of detached particles by splash or flowing water. Therefore, soil erosion is a physical process requiring energy, and its control requires certain measures to dissipate this energy.

Sheet erosion – Soil detachment by the impact of raindrops, transported by shallow sheet flow, and delivery to rill channels.

Rill erosion – Removal of soil by concentrated water running through little streamlets. Rills are less that 4 inches deep, are obliterated by tillage, and typically form in different locations from year to year.

Ephemeral erosion - occurs in natural depressions. It differs from gully erosion in that the area can be crossed by farm equipment.

Gully erosion - makes gullies, some of them huge, impossible to cross with farm machinery.

Soil Conservation became an important concern in the early 1930s, as wind erosion problems became more severe. High-velocity winds swept across the province creating “black blizzards” hence the name “dirty thirties.” The risk of soil erosion by wind is extensive in the Prairie Provinces when the climate is dry and large expanses of open fields are unprotected.

To address the problems and costs associated with soil erosion at a municipal level, the Soil Conservation Act provides municipalities with the authority to take action and/or impose penalties if soil is deteriorating through wind and water erosion or other means. We strongly recommend, however, that efforts first be made to work with the person farming the land and/or the landowner before action is taken under the Act.

The hydrologic processes of rainfall and runoff play an essential role in water erosion. The amount and rate of surface runoff can affect erosion and sediment transport. Thus, soil conservation practices are important in reducing soil erosion. Improving the soil infiltration rate, resulting in less surface runoff, can lead to a reduction in soil erosion. Some situations may require management changes.

The most effective way to control erosion is to maintain a permanent surface cover on the soil surface, such as pasture, hay, or grassed waterways. Areas that are highly susceptible to water or wind erosion need to be considered for soil conservation programs. Soil losses due to water erosion and surface runoff can contribute a great deal to surface water quality concerns.

Plant residue management is another way of controlling soil erosion by intercepting raindrops, thereby reducing surface runoff and protecting soil surface particle detachment by raindrop impact. Crop residue can provide an excellent soil cover after harvest and enhance snow harvesting during the off-season, improve soil water intake by preventing soil surface sealing due to raindrop impact, and consequently, reduce surface runoff. Equally important in minimizing soil erosion is the adoption of a cropping system along with conservation tillage practices such as no-till, strip-till, and reduced till. The degree of effectiveness of different tillage practices depends on the degree of soil manipulation.

Follow other best management practices:

• Wetland Conservation and water retention management
• Zero Tillage, Reduced Tillage
• Crop Rotations
• Grassed areas
• Shelterbelt establishment for wind break development