UCFS ANSI A300
Representative Update
Notes Related to Clause 6: Soil Management
By Gordon Mann
Consulting Arborist
Mann Made Resources
16 CityTREES
S
oil management is the most essential hidden consider-
ation for tree growth. No soil treatment should be made
without sampling to see what is needed. The typical NPK
soil sampling/test shows the nutrients in the soil and the
pH, but it does not give a reasonable picture of the complex
soil microbiomes in play. Through soil genomics testing,
genomics helps us identify what's missing or dysfunctional
in the soil. Once the available and missing fungi or bac-
teria are shown, natural elements and humates can assist
the soil in returning to its natural form, using mulch and
organic matter to support the soil profiles. Once sampling
is completed, adjacent similar soils can be treated similarly.
(Re-test occasionally to ensure conditions remain in place.)
Wood chip mulch from chippers with sharp blades is the least
expensive—and best—treatment for most soils. Mulch decom-
poses, providing organic matter, nutrients, and minerals in
the soil to support root growth. It reduces evaporation and
cools soils in direct sunlight. Bare soil is like a sponge left
on the sink for three days. Both become dry materials with
empty pore space. Water is not readily absorbed by a dry
soil or sponge; it runs off. Integration of organic matter into
soil and use of wood chip mulch allows water to infiltrate
and permeate through the soil profile. In sun-baked exposed
soils, heat and dryness will kill most of the bacteria and fungi
in the soil. This is why direct sunlight is a simple treatment
for soil-borne Oak Root Fungus or Phytophthora infections—
as long as the decay has not spread too dramatically.
Typical soil compaction during construction.
