Soil Compaction in Turf

Daniel Gill, Koske, Thomas J.

Core aerifier gang.

Core tines.

Deep tine core aerifier.

Areas that receive a lot of traffic usually become compacted. The traffic may be foot, hoof or tire, but results are still the same. Soil particles are packed closer together creating a root zone where there is little air, poor percolation of water and a tough medium for roots to grow in. Roots respond to compacted soil with less growth and development, creating a thin and shallow root system. We can generally say, "as is the root, so is the shoot." Stands of turf on compacted soils are generally thin, exhibit stress symptoms more readily and have poor regrowth and recovery from wear.

Soils in gardens and beds can be deeply tilled to break up this compaction. Turf stands are rarely torn up this much, so other means are in order for lawns and sports turf. The most effective form of relief for a compacted lawn is core aerification. In this process, a machine with hollow tines pulls soil cores from the turf to soften the soil and allow roots, air and water to penetrate deeper. These holes are generally 3 to 4 inches deep and the diameter of your finger. To keep these holes open for more than a month, a top dressing of about ¼ to ½ inch of sand is often applied and brushed or dragged into the sod and core holes.

If fertilizer or water salts of sodium are destroying your soil structure and accelerating the compaction, then calcium is often added as gypsum or lime (lime only if pH is low) to help remove the sodium salts and make soils more friable. Core cultivation along with calcium and sand is advised because the calcium is slow to migrate down into the soil by natural movement.

Other forms of turf cultivation that would help compaction removal include spiking (in sands only), slicing and shattercoring. All of these methods require special equipment that is rarely available at tool rentals. Some soil wetting agents can improve moisture penetration, and there are organic materials that might stabilize soil structures, but only the physical disruption of a compacted soil will soften the soil and allow grasses to deepen their root systems and aggressively fill in a thin lawn in hard soil.

If soil compaction is thinning your turf, consider the following. Select a variety of Bermuda grass for your full sun lawn or sports field. Control traffic and provide paths for traffic. Increase the available turf use area to spread the wear. Provide proper fertility and irrigation. Avoid turf traffic when soils are moist. Blend in about 80% coarse sand into the growing medium during a complete renovation.

Where compaction is a problem, turf cultivation can produce obvious effects in a short time. Use turf cultivation monthly as necessary during the growing season. Cultivation is usually done in the spring or summer season for warm-season grasses.

4/21/2005 9:03:54 PM
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