Soil compaction is the result of soil particles being pressed together, reducing the spaces, or pores, between them. Water has a more difficult time wetting the soil, and once it is wet, there is a reduced ability to drain. It is difficult for gases to infiltrate compacted soil, which means the roots get no aeration. A compacted soil also means that roots must exert greater force to spread and grow.

What Causes Soil Compaction?

In agriculture, soil compaction results from the weight of the machinery used to work the field. In home gardens, machinery such as lawnmowers and rototillers can also cause compaction. However, it's most often the result of impatient gardeners walking on or trying to work soil too early in the spring.

To prevent compacting your soil, keep the area small enough so that you can work from the side without stepping in the garden itself. If this isn't possible, place a board on the soil to distribute your weight more evenly. If your soil is already compacted, there are a few things you can do to improve it.

Loosening the soil with a spading fork before planting is an excellent idea. Plunge it into the ground and rock it back and forth to create openings for air and water. Each fall, add a light layer of compost, shredded leaves, peat moss or any organic matter, then cover with two to three inches of organic mulch, such as shredded bark. As the organic matter breaks down, it will loosen the compacted soil.