Radial Trenching

Radial trenching is a treatment performed to trees growing in compacted or poor soils. It is a way to get oxygen to roots, replace soil, and to alleviate compaction.

Radial trenching is performed using an air-spade® to remove soil radially from the trunk out to the roots. Narrow trenches are created using high air pressure in a radial pattern throughout the root zone. These trenches appear similar to the spokes of a wagon wheel. Trenches will be 8-12 inches deep 3-4 inches wide. Using high pressure air tools causes minimal root damage.

Radial Trenching Diagram
Narrow trenches are dug in a spoke pattern around the tree, then backfilled with topsoil or compost. Root growth in the trenches will exceed root growth in the surrounding soil. A 2- to 4-inch layer of wood chips may also be added over the top of the backfilled trenches.

The narrow trenches can be backfilled with the topsoil or compost. Root growth will be greater in the trenched area than in the surrounding soil. This can give the tree the added boost it needs to adapt to the compacted soil or new grade. (photo courtesy of the ISA International Society of Arboriculture).