How Does Soil Become Compacted?

Organic Matter Content

• Soils that contain low amounts of organic matter are more likely to become compacted. Organic matter soil amendments, such as manure, compost and peat moss, can help prevent soil compaction by either increasing the amount of space between soil particles, as in the case of heavy clay soils, or filling in large, empty spaces, such as are found in sandy soils. Always select well-composted materials incorporate them into the top one or two layers of the soil.

Wet Soil

• Working your soil when it is wet may cause soil compaction. According to the University of Delaware Cooperative Extension, fine-textured soils, such as clay soil, are particularly susceptible to compaction when they are worked in wet conditions. Clay soil particles tend to stick together when wet, which significantly reduces pore space and soil oxygen levels. For best results, never work your soil when it is completely saturated, regardless of the type of soil you have in your garden or landscape.

Traffic and Tilling

• Soil compaction is commonly found at construction sites, where heavy equipment places stress on the soil and forces particles to press together. Use of lawn mowers and commercial vehicles may also cause compaction. Regular pedestrian use of soils may also result in compaction, which is often indicated by natural pathways in gardens and lawns where there is frequent foot traffic. Finally, although good tilling practices may reduce compaction, excessive tilling can damage structure and increase the likelihood of compacted conditions. This is particularly common in farmland and agricultural settings.

Signs and Symptoms

• If you recognize any signs or symptoms of soil compaction, you can prevent further problems by treating your soil before planting. According to the University of Delaware Cooperative Extension, symptoms of soil compaction include weak plant root systems, standing water, dense soil that is hard to penetrate and nutrient deficiencies in plants, which result from inadequate aeration. You can treat soil compaction in a variety of ways, including soil replacement, burying soils, soil amendment, or installation of a French drain or other drainage system.