Soil Management: Erosion

Putting It All Together: Erosion

Almost every farm in Ontario is affected by some type of erosion. It is a naturally occurring process. Farming practices have accelerated the rates of erosion, to the point that we are losing topsoil faster than we are creating it.

There are three main types of erosion: water, wind, and to a lesser extent, tillage. They will each be discussed below.

Addressing Erosion Problems

Water Erosion

Water erosion is the movement of soil by water to a new location. When the soil is saturated with water, or when rain is coming down faster than the soil can absorb it, water (such as rainfall) will run off the surface.

Many horticultural field crops, like these grapes, are grown in rows. Spring is the most dangerous time for erosion in row crops, as the inter-row soil is bare - unprotected by crop foliage.

Field Symptoms

• rills or cuts are formed on the soil surface after a rain or snowmelt
• ditchbank grass cover is buried with soil
• gullies formed in the field and tillage equipment can't fill them in
• soil has accumulated at the bottom of slopes or in depressional areas
• soil on knolls is lighter in colour, and stones may be visible on the hilltop and sides
• in the spring, fall-tilled soil seems to flow together
• crops buried with soil.

Crop Symptoms

• varied crop development and yields across a field, with knolls having lower populations and shorter plants
• in drought conditions, crops on knolls stressed before rest of field
• seed exposed in seed trench following an intense rain.

Best Management Practices

• use reduced tillage systems - no-till, minimum tillage, or ridge tillage
• use residue management - aim to leave at least 30% crop residue on the soil surface after planting
• use crop rotations that alternate row crops with solid-seeded crops
• drain wet fields
• construct erosion control structures where needed
• use strip cropping and buffer strips
• till and plant crops across the slope where possible or use a system of contour cropping.

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Wind Erosion

Wind erosion is the process of moving soil by air currents or wind.

Field Symptoms

• soil surface appears smooth or rippled like beach sand
• knolls are lighter in colour
• during winter, the snow has a brown colour
• soil has accumulated on the leeward side of any barriers, e.g. buildings, equipment, trees, ditches, roads.

Crop Symptoms

• seeds or seedlings have been exposed, moved, or buried by soil
• plant may appear wilted or burnt
• stems and leaves have small pits or abrasions
• stems may be stripped of leaves
• crop growth slow, stunted, uneven
• plant population may be uneven.

These newly planted onion sets have been exposed by the action of the wind.

Best Management Practices

• use crop rotations
  • alternate row crops with solid-seeded crops
• maintain and build organic matter levels
  • include forages and cereals in the rotation
  • apply manure (manure management) or other organic materials
• plant green manure crops after short-season crops
• keep the soil covered with cover crops
  • plant as early as possible
• keep the soil surface rough
  • use reduced tillage systems that leave residue and a rough surface
  • aim for 30% surface residue after planting
• plant windbreaks and use other wind abatement systems such as winter rye strips
• use strip cropping to break the sweep of wind.

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Tillage Erosion

Field Symptoms

• soil on knolls/hillsides is lighter in colour and bare
• water erosion is worse than expected on hilltops eroded by tillage
• large amount of soil accumulated on lower slopes
• calcareous subsoil may overlay organic rich soil on lower slope positions.

When you plow or work soil up and down the slope, gravity helps to move more soil downhill than uphill.

Crop Symptoms

• crop growth may be stunted
• crop growth and development are highly variable across the field
• crops may not grow on knolls
• yield losses on eroded areas of 30-50%.

Best Management Practices

• where possible, till across slopes, not up and down slopes
• use reduced tillage systems such as minimum or no-till on hilly land
• keep eroded knolls and hilltops covered in vegetation as long as possible to reduce water erosion
• reduce the speed and depth of tillage operations (see owner's manual for recom-mendations)
• grow cover crops and/or add other organic matter sources such as manure to rehabilitate eroded soils
• if hillsides and knolls are severely eroded or extremely steep, consider retiring the land or planting the area to permanent forages.

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Available in Published Version of Soil Management

• Erosion Overview
• Water Erosion
  • Soil Types
  • Past Management
  • What's Happening in the Soil
• Wind Erosion
  • Soil Types
  • Past Management
  • What's Happening in the Soil
  • Emergency Treatments
• Tillage Erosion
• Soil Types
• Past Management
• What's Happening in the Soil
  

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