Soil and Compost For Trees

Soil and Compost For Trees

• Soil Formation, horizons and ecosystem

• Organic Matter

• Mulch, Compost and Humus

• Compost – the basics

• About trees and soil

Why Worry About Soil?

• It’s the foundation for tree growth and

health

• It cycles most nutrients and is a huge C sink

• It can be degraded or lost easily

• For every pound of food we produce we

loose 22 pounds of soil

• It takes hundreds to thousands of years to

make an inch of soil

Formation of Soil

• Climate

• Parent Material (rock)

• Topography

• Time

• Living organisms

• People can help

“Nature and Properties of Soil”

•

What is Soil?

• Soil is the end product of the influence of

the climate, relief (slope), organisms, parent

materials (original minerals), and time.

• In horticulture, the term 'soil' is defined as

the layer that contains organic material that

influences and has been influenced by plant

roots, and may range in depth from inches

to many feet.Wikipedia

Soil Horizons or Layers

• O – Organic Matter

• A – Mixture of mineral and humus

• B – More minerals, less organic material

• C – Broken parent material

• Parent material or regolith

Soil Depth

• Defined by depth to restrictive layer – rock,

heavy clay, etc

• Shallow – 10 to 20 inches deep

• Deep – 36 to 60 inches

Per Arizona Extension

Soil Building Blocks

• Sand – largest particle, lots of pore space

• Silt – small particles, moderates effects of

sand and clay

• Clay – very small particles, sticky, doesn’t

breath well

How much water will my soil

hold?

Soil Type In 2 Feet In 3 Feet

Sand 1.25” 1.75”

Silt Loam 2.2” 3.4”

Clay Loam 2.0” 3.0”

Clay 1.9” 2.8”

SURFACE AREA IN 2 TABLESPOONS

OF SOIL EQUALS ONE CITY BLOCK

The Micro Living Room

It’s Alive!!!!!

Soil Ecosystem

Number and Biomass of Soil Organisms

Number/ Number/ Biomass

Organisms yd3 oz (Lbs/Acre-6”)

Bacteria Trillions Millions + 400 – 4.000

Actinomycetes Trillions Millions 400 – 4.000

Fungi Billions Thousands + 500 – 5,000

Algae Billions Thousands 20 - 500

Protozoa Billions Thousands 15 – 150

Nematodes Millions Tens + 10 – 100

Earthworms 30 – 300 100 – 1,000

4% organic matter is 80,000 lbs per acre

Decrease to 1% means loss of 60,000 lbs per acre

Symbiosis

• The idea of evolution driven by competition may be incomplete and is instead based on cooperation, interaction, and mutual dependence among organisms

Ecosystem

Cycles

•N cycle - protein

• C cycle – plant material

• Water cycle

• Short circuiting cycles

• Recycling?

The Nitrogen Cycle

Dung Beetles

Burrowing creatures can greatly enhance

fertility, air and water infiltration

Collembola - Springtails

Nematode trapping fungi

Mycorrhizae fungi

Mulch, Compost and Humus

Mulch

• Organic or inorganic covering over the soil

• Can be compost, bark, leaves, gravel,

plastic, etc

Benefits of Mulch

• Moderate soil temperature

• Improve water penetration

• Reduce soil compaction

• Retain soil moisture

• Reduce weed problems

• Can be used to keep produce off the ground

Compost

• Decomposition of organic materials with

cycling of nutrients

Benefits of Compost

• Recycles organic materials

• Builds soil structure and improves aeration

and moisture properties

• Cycles and releases nutrients for plant use

• Foundation for life in the soil

Humus

• Dark colored semi-stable organic material

• Composed of material resistant to

decomposition such as lignin, fats

Compost Methods

Composting

• Air

• Moisture

• Food source

What Are My Goals?

• What materials do I want/need to compost?

• Do I need to get my pile hot? (Over 130

degrees kills weed seeds and diseases)

Slow Composting

• Layers

• Ensure adequate moisture

• Leaves can form a “roof”

• Mix of nutrients

Fast Composting

• Right mix of materials

• Moisture

• Air flow

• Turn and mix

What Can I Compost?

• Theoretically anything organic

• Avoid fecal material of humans or pets

Decide on pile or bin

• Bins help retain moisture and can exclude

animals

• Large bins or piles may be required for

large amounts of material but can be hard to

manage

• At least three feet on each side to retain

moisture, heat

Mix Materials

Water

• Compost should feel like a damp sponge

Turn Every Week or Two

How will a tree’s roots grow?

• Type of tree

• Soil type and depth

• Watering/drying cycle

• Nutrients

• And…

Trees with fibrous roots

• Maple

• Ash

• Cottonwood

• Cypress

Trees with taproots

• Oaks

• Walnut

• Pines

• Pecans

• Mesquites

How to use Compost and Mulch?

• Never mix compost with the tree planting

soil – this creates a “pot” effect

• Place a layer of compost on the surface

• Cover compost with a layer of mulch 2’ –

6”

• Try to keep the soil covered

Mesquite roots

can be 100 feet deep

Questions?