University of Florida

Home > Health and maintenance > Solve problems > Top of canopy dying > Compacting the soil

Compacting the soil under the canopy

tractor compacting soil around treesMowing can cause decline.
Despite the imposing nature of a large mature shade tree, tree roots are in a delicate balance with soil. A few passes with a large heavy machine under the canopy can dramatically change the ability of soil to support root growth.

Compacting soil under the tree canopy reduces the air space between soil particles. This slows down air and water exchange with the atmosphere. Tree roots grow very poorly in compacted soil; this can quickly lead to a sharp decline in health.

There are several methods of preventing soil compaction on a construction site. 1) Hire a consulting arborist; 2) Construct a fence at the edge of the tree canopy to prevent ALL vehicles from operating there and establish fines for violations; 3) A 12-inch thick layer of coarse bark mulch can be spread under the canopy and mulch can be covered with steel plates. Vehicles drive on the plates. This system has been successfully used on many sites to preserve mature trees;4) Do not use the area under the canopy as a parking zone or materials storage area; 5) Restrict ALL vehicles to fenced-off transportation corridors and materials storage areas.

An Airspade or Supersonic Air Knife can be used to loosen compacted soil. Roots should grow very well in this loosened soil.