Three Types of Erosion Threatening Ontario Farms
Erosion is not a single problem — it's three distinct processes, each with different causes, indicators, and management solutions. The Farmland Health Check-Up evaluates all three forms on each of your assessed fields, because understanding which type is active determines which Best Management Practices will be effective. This is a key component of the 3-field comparison approach.
Water Erosion
Water erosion is the detachment and transport of soil particles by rainfall impact and surface runoff. Steeply sloping fields with converging slopes and loamy soils are among the soil conditions at most risk. Look for finger-like and slightly larger channels (rills) on upper-slope positions as well as fan-shaped areas of soil deposition downslope as evidence of previous water erosion.
The FHCU evaluates water erosion risk using slope class, slope length, soil erodibility factor (K-factor), crop rotation, and residue management. Fields with slopes exceeding 5% (C-class) on erosion-susceptible soils require active erosion management — including contour farming, buffer strips, grassed waterways, or terracing — to prevent ongoing productivity loss.
The Hidden Input Cost
The economic impact extends beyond topsoil loss. Water erosion carries applied nutrients, crop protection products, and organic matter off the field — representing a direct loss of purchased inputs as well as inherent soil fertility. On a field losing 5 tonnes of soil per acre annually, the nutrient value of that lost material can exceed $20–30/acre/year.
Wind Erosion
Open and unprotected croplands with sandy soils are most prone to wind erosion. If you can see soil material moving across your field surface, it is estimated that up to 5 tons per acre may be lost. Wind erosion is most active on sand plains (such as Norfolk, Brant, and Simcoe counties) during spring when fields are bare, soils are dry, and wind speeds are highest.
Common Problems We See
The FHCU assesses wind erosion vulnerability based on soil texture, field length in the prevailing wind direction, surface roughness from residue or cover crops, and the presence of windbreaks. Sandy soils with less than 30% residue cover and no windbreak protection are at highest risk.
Tillage Erosion
Tillage erosion is the most underestimated form of soil degradation on Ontario farms. It occurs through the systematic, gravity-assisted movement of soil downslope during tillage operations. Every pass of a plow, cultivator, or disc moves soil a short distance — always net downhill. Over decades, this process strips topsoil from upper slope and knoll positions and deposits it in lower landscape positions.
Key Takeaway: On fields with complex slopes and a history of downslope tillage, tillage erosion can remove more soil than water erosion — the relocation of topsoil results in extreme productivity loss on knolls and shoulder slope positions. See how this connects to yield plateaus across Ontario.
The result is the characteristic "whitecaps" or eroded knolls visible in many Ontario fields — lighter-coloured hilltop areas where subsoil or parent material has been exposed at the surface. These areas represent the loss of the entire A-horizon (topsoil) and often part of the B-horizon.
The FHCU evaluates tillage erosion through slope complexity analysis, tillage direction assessment, and visual identification of subsoil exposure on upper landscape positions.
Eroded Knolls: The Hidden Yield Drain
Severe Productivity Loss
Eroded knolls are areas where almost a metre of soil has been lost from upper slope positions, exposing the parent material at the surface. Crops growing on eroded knolls may yield 50–70% less than the same crop on adjacent protected landscape positions.
Ontario soils developed on glacial deposits over 12,000 years. The full soil profile — from topsoil through the B-horizon to parent material — typically extends only 60–120 cm. When tillage erosion removes this shallow profile from knoll positions, the remaining "soil" is unweathered, low in organic matter, poorly structured, and hostile to root growth.
