Compacted Soil and Grasses

About Soil Compaction

• All soils are composed of soil particles and the pores between them. Soils with a large amount of space between soil particles are fast-draining, whereas smaller pores create slower drainage. In compacted soils, the particles are compressed, resulting in decreased drainage and aeration. Soil compaction is common in areas of the lawn that receive heavy traffic, since the particles become pressed together.

Effects

• In compacted soils, grass roots do not receive enough aeration since they cannot press through the compressed soil. Essentially, grass roots will drown when watered, since they have no space to breathe. This will result in nutrient deficiencies and increased susceptibility to pests and diseases. Soil compaction also causes water to run off the surface of the lawn, since it cannot penetrate the soil, which causes soil erosion. According to Clemson Cooperative Extension, soil compaction also contributes to thatch, since organisms that usually decompose thatch are not supplied with enough oxygen.

Symptoms

• If you are unsure whether your soil is compacted, you can look for a few tell-tale signs. Compacted lawns tend to accumulate large pools of water, since the soil is too tightly packed to absorb the water. The soil will also be very hard to penetrate with your hands or a shovel. To identify compacted soil, remove a one square-foot sample of grass from your lawn. If the grass roots only extend one or two inches into the soil, you should consider aerating your lawn.

Aerating Your Lawn

• Compacted lawns can be remedied by soil aeration practices. If a small portion of your lawn is compacted, you can probably aerate by hand using a spading fork. Insert the spading fork into the soil and make a large hole about four inches deep in the soil. Make more holes about every two to six inches throughout the compacted area. For large-scale compaction, use a core aerator to make holes in the soil. Be sure that you water the lawn two days before aerating, and aerate when the soil is moist but not wet.