Friday, July 20, 2012

Your Backyard Woods - Avoiding Soil Compaction

Soil compaction reduces water infiltration by reducing the number and size of soil spaces. Driving vehicles in your woods compacts the soil. Compaction can occur by driving one pickup truck of firewood over the ground under your trees. As the number of pickup passes increase, over the same area, the compaction becomes severe and can take many years to recover. Wet soils are more susceptible to compaction than dry soils, and clay and loam soils are more susceptible than sandy soils.

Uncontrolled livestock access can cause more serious compaction than periodic vehicle use because it covers a greater portion of your woods and for a longer period of time. Water infiltration rate is lowered in compacted areas and surface runoff will occur. The distance the water travels overland depends on the extent of the compacted area. If the overland flow reaches an area with no compaction, the water will infiltrate. Soil erosion is scattered across the grazed area, but normally does not leave your land except when livestock trails end at gullies and streams.

Uncontrolled livestock access can cause serious impact to some woods, altering water movement. Compacted soils hinder root growth and reduce tree health. The majority of tree root systems are within 3 feet of the soil surface and most of the fine roots are within 8 inches of the surface. Long-term uncontrolled livestock access damages these roots, killing young trees first, but eventually killing all the trees, converting your woods to an open pasture. Infiltration rates are reduced and overland flow rates increase in the overgrazed pasture.

Roads and trails that cross a stream or even a channel that only contains water periodically are primary entry points for soil into streams. The bare compacted soil in the road, trail, or road ditch is like a channel carrying water and its load of soil into a stream. The solution for this problem is to remove the water from the road or trail before it layer where it can slow down, spread out, and sink into the ground, depositing its soil onto the litter layer.

Many states have developed practices that will help you control road and trail overland flow, and build a gully or stream crossing. They are called Best Management Practices(BMPs)  for Water Quality, and information on how to install them can be found at our Soil and Water Conservation District office.
Controlled livestock access is the best way to solve compaction and litter layer problems caused by livestock. Methods vary by location and tree type. In some tree types, it is best to eliminate access. In other tree types, trees and grass can be produced on the same area in a managed system.

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