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Soil Management For Trees

Introduction to speaker:

• Kent Honl, Arborologist at Rainbow

Companies

• ISA Board Certified Master Arborist

MN 0158B

• Adjunct Faculty in Arboriculture at

Hennepin Technical College,

Brooklyn Park, Minnesota

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Intended Outcomes

• Understanding the soil compaction and soil oxygen relationship

• How to recognize symptoms in a tree that are soil related

problems

• Root enhancements to improve tree health

• The tools available to help improve soil conditions

• How to improve root growth in a changed soil environment

• How to sell soil management services to your client

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• Structural support

• Nutrients

• Water

• Oxygen

What do trees get from soils?

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Thin Air

What are trees made of?

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PHOTOSYNTHESIS RESPIRATION

THE MEANING OF LIFE:

Energy Capture -- Energy Release 6

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Where Roots Really Are:

2-4X the width of the dripline

Top 10-12”

of the soil -

where the

oxygen is!

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https://www.studyblue.com/notes/note/n/chapter-12-part-2-/deck/861365

http://courses.soil.ncsu.edu/resources/physics/composition/compo3b.png

Ideal soil for trees:

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Urban Soils: A Far Different Story

Greatly reduced conditions

for root function and health

Soil compaction, low organic matter

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Urban Soils: Departure From Ideal

Compaction Low Organic Matter

Compaction reduces the pore

space in between particles • Reduces water infiltration

• Reduces soil oxygen

• Reduces root penetration

Forest soils have

defined O horizon:

Urban soils almost always

have this removed

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The Main Properties of Soils

•Chemical

•Physical

•Biological

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Chemical Properties of Soils

17 Nutrients

Used in large amounts, usually applied as

supplemental fertilizer

Used in large amounts, but commonly available

Needed in only small amounts (but still important)

http://www.ext.colostate.edu/mg/gardennotes/231.html 12

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ree & Soils

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Physical Properties of Soils Soil Texture

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Soil Structure

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Biological Properties of Soils

http://www2.mcdaniel.edu/Biology/eco/soil/xsoilcritters.htm

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How many arborists

deal with these?

• New homes, new landscapes

• Trees lacking vigor

• Trees with root issues: girdling, etc

• Mature trees in limited root area

• Nutrient deficiencies

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Symptoms of Soil Related Tree Problems • Tip dieback

• Early fall color

• Chlorosis

• General decline

• „Telephone pole‟

Most tree problems ARE soil related! 18

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Host

Disease Triangle

Environment Pathogen

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Change or modify

the HOST

Control the

PATHOGEN

How can we intervene?

Change or modify

the ENVIRONMENT

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Prescription Fertilization Soil injected fertilizer

Standard formula set for

predominant soil tests

in your area

Add custom

amendments as needed

(pH adjusment, etc)

21 Modifying the chemistry of soil environment

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Benefits of Mulch

• Regulates soil moisture and

temperature

• Removes competition with turf grass

• Keeps mowers and weed whips at bay

• Recycles urban wood waste

Pic: G. Watson

Over the long term, mulch tends to

replicate forest soil:

• Less compacted

• More acidic

• Better for tree roots 22

How to introduce organic matter?

New addition to our RES service

Organic matter

improves soil

properties in all

3 areas:

• Chemical

• Physical

• Biological

Root Enhancement Service

• Loosen a large

volume of soil

around the base of a

tree with the

AirSpade®

• Incorporate organic

matter

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25 Starting point: estimate root flare depth

Root Enhancement Service

Stage 1: Root Collar Excavation • Many species are prone to Stem

Girdling Roots – Maples – Lindens

• 90% of trees planted too deep

– Deep planting leads to SGR formation

– Root removal is critical to enhance survival

Primary reason Rainbow began using AirSpade® 26

Root Collar Excavation:

Time to decide what to do

• Cut off ALL girdling roots?

• Cut off a given percentage?

• Walk away?

Some trees tilt or topple after SGR removal… 27

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Cross section area -SGRs removed

“Girdling roots can be removed until cross sectional area is 25% of trunk cross sectional area at 4.5 feet…”

How many roots can we remove? Here is what it looks like

Table of cross sectional areas Diameter Cross section area 25% of cross section area

1 inch 0.785 sq inch NA (Root)

2 inches 3.14 sq inches NA (Root)

3 inches 7 sq inches NA (Root)

4 inches 12.5 sq inches NA (Root)

10 inches 78.5 sq inches 19.6 sq inches

12 inches 113 sq inches 28 sq inches

15 inches 177 sq inches 44 sq inches

20 inches 314 sq inches 71 sq inches

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Stage 2: Root Enhancement (if tree is deemed viable after root collar exam/girdling root removal)

Remove sod within a

3, 5 or 7 ft. radius

Decompact soil with

AirSpade®

Use AirSpade® to mix in composted OM, other amendments: (pH adjustments etc)

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One gram = surface

area larger than a

football field;

>100m2/g

Biochar

Root Enhancement Stir in Prescription Organic Matter and Amendments

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Finishing Up:

Thorough watering eases stress of desiccation from forced air 33

Top Dress with Mulch & Water

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Managing client expectations is important

Clearly describing aftercare is critical as well: WATER YOUR TREE! WATER YOUR TREE!

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RES does not always save the tree

The tree will not “bounce back” in a day or two

Recovery is a process, often taking years to complete

Additional Uses of AirSpade® “Daylighting” Cleanly exposes root flares for injections

Expose utilities so they are visible before stump grinding, etc.

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Plant Growth Managers

Increases Absicic acid:

Plant protection hormone

Stimulates Root Growth

Triggers closing of stomata to keep up with transpiration

Protects cells from

dehydration

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Red Oak, 3 years after treatment

Treated trees have darker green leaves and produce more chlorophyll

Untreated

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Photos Taken 1 Year After Trees Were Planted Study Done At Morton Arboretum – Dr. Gary Watson

Using Cambistat™ to increase a tree‟s root mass Newly Transplanted Sugar Maple

Untreated

(Apply Cambistat™ AFTER using the AirSpade®, not before!) 38

• Xytect (imidacloprid)

• Transtect (dinotefuron)

• Lepitect (acephate)

Soil-Applied Insecticides Each has its own rate of absorption, duration of effectiveness, and list of insects it can control

Apply AFTER AirSpade™ work is complete!

HTI soil inject or soil drench

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In Review: • The Meaning of Life: Energy Capture, Energy Release

• What makes a good environment for root function

• Most tree problems are soil problems

• Organic matter improves all soil properties:

– chemical, physical, biological

• Tools are available to help improve soil conditions

• Importance of expectation management with clients