Organic Soil Management
Organic Soil Management
Using organic principals to maintain
healthy soils and healthy plants
© Helen Tuton Horticultural Services 2014
With Thanks To
© Helen Tuton Horticultural Services 2014
Getting Started?
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It is easy to create a beautiful
garden that will have low
impact on our natural
environment.
This workshop will help you
understand your soil and how
to improve it.
There will be plenty of
opportunity for Q&A through
the session and at the end of
the presentation.
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
1
Organic Soil Management
The Importance of Soils
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Soil is vital to healthy plant growth as it:
 Supports the plant’s roots.
 Supplies the majority of nutrients needed
by the plant.
 Provides the water needed to carry
nutrients throughout the plant.
 Provides oxygen to the
plant.
 Is home to countless
symbiotic organisms that
the plant depends on for
survival such as worms,
fungi and bacteria.
© Helen Tuton Horticultural Services 2014
Ideal Soils
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Should be:
 Be high in organic
matter.
 Have good drainage.
 Have good aeration.
 Hold nutrients.
 Have healthy soil flora
and fauna – fungi,
bacteria, and worms.
 Be friable.
© Helen Tuton Horticultural Services 2014
Soil Types – Sand
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Poor water holding
ability.
Excellent drainage.
May be hydrophobic.
Leaches nutrients.
Easy to cultivate.
Small pockets of Hobsons Bay and surrounds
has sandy topsoil.
Sandy soils can be improved
with organic matter
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
2
Organic Soil Management
Soil Types - Loam
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A combination of fine and coarse particles.
Good water holding ability.
Good drainage.
Easy to cultivate.
Good nutrient holding
ability.
Loam soils can be maintained
with organic matter
© Helen Tuton Horticultural Services 2014
Soil Types - Clay
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Good water holding
ability.
Good nutrient
retention.
May have poor drainage.
May have low aeration.
May be difficult
Clay soils can be improved
cultivate.
with organic matter
Many areas of Hobsons Bay have clay layers
close to the surface, mostly basalt clay soil
from lava flows.
© Helen Tuton Horticultural Services 2014
Other Soil Characteristics
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A duplex soil is a combination of soil types.
Duplex soils may be prone to water logging due
to different percolation rates of soil.
Shallow soils (depth of less than 50cm) are
typically found in areas of low rainfall.
Deep soils (depth greater than 1 metre) are
typically found in areas of high
rain fall.
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
3
Organic Soil Management
Where to Start – Clay Soils
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Poor drainage and hydrophobic soils are the
most common issues faced on clay soils.
For heavy sodic clay soils apply a dressing of
gypsum and lightly dig it in.
Gypsum:
 is a naturally derived mineral product.
 breaks up clay & improves drainage without
altering the pH.
Follow application with a good layer of mulch
and keep it topped up as it decomposes.
© Helen Tuton Horticultural Services 2014
Poor Drainage – Mounding?
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You might consider building mounds if:
 Your soil is dreadful, adding garden loam
on top seems the easiest way.
 Your soil drains badly and you need to
build it up.
 You need to create a sound or visual
barrier around your block or add aesthetic
appeal.
But consider that mounds:
 dry out faster than un-mounded beds.
 can be difficult to water as water runs off
the sides.
Careful cultivation and preparation eliminates
the need to mound
© Helen Tuton Horticultural Services 2014
Hydrophobic Soils – What to
do.
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All types of soils can become hydrophobic.
Soils have to be “reminded” how to take up
water again by the adding organic matter.
Use aged composts and manures, and
organically derived mulches
Consider the application of a “granular soil
wetter” to improve water penetration but:
 Be aware that some soil wetters can harm
frogs and small reptiles.
 What about water
crystals??
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
4
Organic Soil Management
Improve your soil
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Compost can be made at home or
is readily available commercially.
Aged animal manures and worm
Compost
compost are rich in nutrients.
Mulch layers will also
break down over time to
add nutrients to the soil.
Compost teas make
Aged Cow Manure
excellent garden fertilisers.
Pea Straw
© Helen Tuton Horticultural Services 2014
How does Compost help?
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Compost (organic matter) is
added to the soil to improve
its:
 Structure and texture.
 Ability to hold water.
 Ability to hold nutrients.
 Ability to regenerate
naturally.
© Helen Tuton Horticultural Services 2014
Organic Mulches
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Mulch keeps the soil temperature
cool in hot conditions assisting
root development and growth.
Prevents weeds from
germinating by blocking light
from dormant seed.
Bark chips, leaf litter,
shredded paper, lucerne
and straw are all examples
of organic mulches.
Organic mulches are broken down
by soil microbes adding valuable nutrients to
the soil.
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
5
Organic Soil Management
Soil Fauna - Microorganisms
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Millions of microorganisms (e.g. fungi and
bacteria) make up the living component of soil.
Microorganisms thrive in clay soils and soils
rich in organic matter.
Three quarters of all soil
microorganisms live in the
top 50mm of the soil.
Microorganisms break
down organic matter and
release nutrients back into the soil.
© Helen Tuton Horticultural Services 2014
Soil Fauna - Worms
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Worms aerate the soil and
can increase its water
holding capacity by up to 10
per cent.
Worms physically break
down organic materials
after they have first been
decomposed by soil
microorganisms.
Worms mix organic
materials and nutrients
through the soil.
Worms improve soil
crumbing/structure
(friability).
© Helen Tuton Horticultural Services 2014
Healthy Soil Fauna
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To maintain healthy populations of soil fauna:
 Reduce unnecessary soil cultivation.
 Continually top up organic matter on the
soil surface.
 Improve drainage in heavy clay soils or
where the soil is compacted.
 Protect the soil from harsh temperatures
and moisture loss.
 Reduce or stop the use of garden chemicals
e.g. herbicides, fungicides, insecticides and
miticides.
 Stop the use of artificial garden fertilisers.
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
6
Organic Soil Management
Soil Conditioners
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Seaweed Solutions stimulate root
growth.
Aged animal manures & other
organic matter boost
microorganism populations.
Green Manure crops add
nitrogen to the soil.
Straws act as a mulch but
breaks down rapidly to provide
nutrients to the soil.
Vermicompost, both the
castings and liquid, are excellent
stimulants for microbial activity
in the soil.
© Helen Tuton Horticultural Services 2014
Your Soils History
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In many areas of Melbourne, the history of the
soil can be critical
There are pockets of contaminated soils through
Melbourne, and Hobsons Bay
Research the history of your block, and
investigate further if your block is
 Ex-industrial land
 Ex-Gasworks/railway/chemical
 Ex military
 Ex landfill
Use ONLY NATA accredited testing agencies
© Helen Tuton Horticultural Services 2014
Ok…..relax
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More often than not, our “urbic” soils are
“dead”, not contaminated
Many soils through Hobsons Bay have been
overworked, stripped of nutrient and unloved
Just because you have issues with plants
growing, doesn’t mean your soil is
contaminated!
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
7
Organic Soil Management
Soil pH
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pH is the measure of acidity
or alkalinity of the soil.
pH affects the ability
of the
plant to access available nutrients.
The preferred pH range for most garden plants
is between 6.0 and 7.5.
Soil pH is easily tested by the home gardener
with a pH testing kit.
If the pH is too low (acid), it can be raised with
Dolomite of Lime.
If the pH is too high (alkaline), it can be
lowered with sawdust from untreated timbers.
© Helen Tuton Horticultural Services 2014
Soil pH for Natives
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The origin of your native plants will determine
their preferred pH range:
 Eg: Western Australian natives prefer
slightly alkaline, sandy soils.
 Plants locally native to the Manningham
region generally prefer a neutral to slightly
acidic clay based soil.
© Helen Tuton Horticultural Services 2014
Soil Ph for Vegetables
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Some vegetables and herbs have
specific ph range that they
prefer. Eg:
 Cucumbers ph of 6.0 to 7.0
 Pumpkin ph of 5.5 to 7.0
 Beans ph of 6.5 to 7.5
 Corn ph of 6.0
to 7.0
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
8
Organic Soil Management
Nutrient Requirements
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Australian soils are traditionally low in
nutrients and native plants have lower
nutrient requirements than exotic plants.
Fertilisers should be used at half strength or
use a purpose formulated native plant
fertiliser.
Australian native plants
in the Proteaceae family
e.g. Grevilleas and
Banksias are highly
intolerant
of phosphorus.
© Helen Tuton Horticultural Services 2014
Nutrients for Vegetables
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Most food producing plants will benefit from
supplementary fertilisers applied fortnightly
during the growing period.
Choose an organic liquid fertiliser such as
worm wee, seaweed solution or fish emulsions.
You can also make your
own compost teas from
some homemade compost or
dried animal manures.
Add aged manures ready for
spring planting.
© Helen Tuton Horticultural Services 2014
Summary
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Healthy plants begin with healthy soil.
Hobsons Bay and surrounding soils tend to be
clay which can be hydrophobic or poorly
drained.
The addition of soil conditioners like Gypsum
can help overcoming heavy soils.
Adding organic matter is beneficial for all soils
types and aids in overcoming poor drainage
and hydrophobic soil.
Plants have specific PH and
soil requirements.
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
9
Organic Soil Management
Further Information
For extensive information on a wide range
of sustainable gardening practices and to sign
up for their free monthly newsletter, visit
www.sgaonline.org.au
And check out the Hobsons Bay
and My Smart Garden websites
for many more resources!
© Helen Tuton Horticultural Services 2014
© Helen Tuton Horticultural Services
2014
10