Soil Compaction

Most terrestrial plants are highly dependent on the soil for their well-being. A very favorable soil contains 50% open “pore” space, 45% minerals, and 5% organic material. The pore spaces in the soil are very important to store water, air, and other gasses and provide open spaces for root growth and development. A condition that dramatically impacts the productivity of the soils is soil compaction, which occurs when heavy objects run over the soil and compress it to the point that pore spaces are reduced. Repeated compression of soil results in a compacted soil with very small pore spaces. Some of the more common compaction occurs with heavy equipment, large animals, people, and heavy watering. This loss of pore space limits root penetration, so that trees have superficial roots or an abundance of surface roots. Roots are important because they collect water and nutrients, and secure the tree to the ground.

Compacted soil also inhibits water absorption so much more runoff occurs and the soil is less able to retain water. Soil compaction affects aeration; and the reduced air flow affects root growth, causes buildup of toxic substances, and results in higher soil temperatures which can destroy tree roots and other microscopic and macroscopic plants and animals.

If soil compaction is so damaging, how can we prevent or repair compacted soil? Limiting access to the forest and landscape is the best preventative measure we can take. Using mulch around trees or designating walkways is another good idea. Ways to correct compacted soils include tillage, incorporating organic matter into the soil, cultivating plants and flowers, encouraging earthworms with mulch and organic material, and fertilizing trees.

Article by Mike Kay, FCFCDB member

Nature Note for 5/28/22