Brisbane Organic Growers
Healthy soil, strong plants, healthy people
Soil Types around Brisbane
Brisbane has four main soil types:
• dark alluvial soils
• deep red loamy soils
• gravelly red and yellow loamy top soils over
• shallow gravelly soils
Dark alluvial soils
Dark alluvial soils
Deep red loamy soils
Deep red loamy soils
Gravelly red and yellow loamy top soils over clay
Bald Hills, Brookfield, Eagle Farm, Fig Tree Pocket, Hamilton and Hendra
Bulimba, Fairfield, Hawthorne, Jindalee, Runcorn, Tennyson
Boondall, Bracken Ridge, Bridgeman Downs, Carseldine, Clayfield, Moggill,
Chelmer, Corinda, Eight Mile Plains, Graceville, Kuraby, Lota, Macgregor, Manly,
Manly West, Oxley, Robertson, Rochedale, Sherwood Sunnybank, Sunnybank
Hills, Wynnum
Alderley, Anstead, Aspley, Auchenflower, Banks Creek, Banyo, Bardon,
Bellbowrie, Brighton, Chapel Hill, Chermside, Deagon, England Creek, Enoggera,
Enoggera Reserve, Everton Park, Ferny Grove, Fitzgibbon, Gaythorne, Geebung,
Gordon Park, Grange, Grovely, Herston, Indooroopilly, Karana Downs, Kedron,
Kelvin Grove, Kenmore, Kenmore Hills, Keperra, Kholo, Lake Manchester,
McDowall, Milton, Mitchelton, Mt Crosby, Newmarket, Northgate, Nudgee
Beach, Nundah, Paddington, Pinjarra Hills, Pinkenba, Pullenvale, Red Hill,
Sandgate, Shorncliffe, Spring Hill, St Lucia, Stafford, Stafford Heights, Taigum,
Taringa, Toowong, Upper Brookfield, Upper Kedron, Virginia, Wavell Heights,
Wilston, Wooloowin, Zillmere
Gravelly red and yellow loamy top soils over clay
Acacia Ridge, Algester, Annerley, Archerfield, Balmoral, Belmont, Berrinba,
Burbank, Calamvale, Carindale, Chandler, Coopers Plains, Coorparoo, Darra,
Doolandella, Drewvale, Durack, East Brisbane, Ellen Grove, Forest Lake,
Greenslopes, Gumdale, Heathwood, Hemmant, Highgate Hill, Holland Park,
Holland Park West, Inala, Jamboree Heights, Karawatha, Larapinta, Lytton,
Mackenzie, Mansfield, Middle Park, Moorooka, Morningside, Mt Gravatt East,
Mt Ommaney, Murarrie, Norman Park, Pallara, Parkinson, Ransome, Richlands,
Riverhills, Rocklea, Salisbury, Seventeen Mile Rocks, Sinnamon Park, South
Brisbane, Stretton, Sumner, Tarragindi, Tingalpa, Upper Mt Gravatt, Wacol,
Wakerley, West End, Westlake, Willawong, Wishart, Woolloongabba, Wynnum
West, Yeerongpilly and Yeronga
Shallow gravelly soils
Albion, Ascot, Ashgrove, Bowen Hills, Chermside West, Fortitude Valley,
Lutwyche, Mt Coot-tha, New Farm, Newstead, The Gap, Windsor
Shallow gravelly soils
Camp Hill, Cannon Hill, Carina, Carina Heights, Dutton Park, Kangaroo Point, Mt
Gravatt, Nathan and Seven Hills
Types of soil
Soil profiles explained
• O) Organic matter: Litter layer of plant
• A) Surface soil/Top Soil: Layer of mineral
soil with most organic matter
accumulation and soil life.
• B) Subsoil: This layer accumulates iron,
clay, aluminium and organic
compounds, a process referred
to as illuviation.
• C) Parent rock: Layer of large unbroken rocks.
This layer may accumulate the more
soluble compounds .
• R) Bedrock: R horizons denote the layer of
partially weathered bedrock at the
base of the soil profile. Unlike the
above layers, R horizons largely
comprise continuous masses (as
opposed to boulders) of hard rock that
cannot be excavated by hand. Soils
formed in situ will exhibit strong
similarities to this bedrock layer.
How to self-test your soil
Texture vs Structure
• #1 The Squeeze Test-take a handful of moist
soil, squeeze and open your hand
– Holds, but crumble with a light poke, yippee you have luxurious loam
– Holds, but sits in a lump when poked, you have a
clay soil
– Falls apart when you open your hand, you have a
sandy soil
How to self-test your soil
• #2 The Percolation Test- to test your drainage
– Dig a hole 30x30x30cm
– Fill with water a allow to drain completely
– Fill the hole again with water
– Keep track of how long to drain
• > 4hrs = poor drainage
How to self-test your soil
• #3 The Worm Test
– Dig a hole 30x30x30
– Place the soil on cardboard
– Sift through and count the worms
• > 10 worms = pretty good + heaps of microbes and
• Less worms = not enough organic matter and/or pH is
too high or low
How to self-test your soil
• #4 pH Test
– Pick up a pH test kit from your garden centre
– Do the simple test from various areas in the
• pH 6-7.5
• pH < 5
• pH > 8
neutral, suits most plants, maximise
nutrient availability
acidic, most plants will not grow well and
limited nutrient availability
alkaline, most plants will not grow well
and limited nutrient availability
Why is pH important?
Where did it all go wrong?
• Natural recycling of nutrients in the topsoil –
• Farmers and gardeners had always worked on
these principles
• Justus von Liebig -19th century- NH3
– Led to chemical fertilisers-NPK
– Later developed Law of Minimum – all nutrients and
minerals need to be present
• Chemical companies made NPK-how they
changed their habits, easy to use
A Soil Comparison
Healthy Soil
In balance - nutrients
Earthy sweet smell
Full of earthworms
Full of minerals
Good structure
– Dig with your hands
• Plenty of organic matter
• Healthy pH
• Biologically active
‘Dead’ Soil
Overuse of chemicals
Depleted in organic matter
Sandy soils dry and lifeless
Clay soils like rock
No earthworms
Dig with a mattock– if your lucky
• Often acidic
• Biologically dead
• If a good soil could be achieved by buying
bags from the garden centre, we would all
have great soils
– Sample
• The basis for a healthy soil is organic matter
and the recycling nutrients and minerals
– More about this later
The Good and The Bad News
You can have a healthy soil
Good news - no matter what type of soil
you have, you can make good soil
Bad news – may need a little know how,
some work and patience
Making Good from Bad, Better from Good
• Whether your soil is clayey, sandy, loamy, low
in nutrients, compacted or has poor drainage:
– Add organic matter
– Add organic matter
– Adding organic matter is the best way to improve
your soil
– Never throw away anything organic again
• Think of your soil as a living organism
• Feed your soil, if your soil is healthy and
in balance your plants will love you for it
• Ask yourself, will this be good or bad for
my soil
• Think about the Soil Food Web
• "The soil is like a farmer's bank. You've
got to keep making deposits into it all the
time. If you withdraw from it until it's
empty, you'll be out of business."
How to feed your soil
• Feed your soil
– Organic matter
– Minerals
– Nutrients
Organic Matter
1. Compost
Soil structure
– Layers of Carbon(C)
• Hay, leaves, grass, weeds, cardboard, paper, straw,
pruning's etc. – NEVER throw out anything organic
– Layers of Nitrogen(N)
• Manures, blood & bone, comfrey, seaweed, legumes,
organic fertiliser, kitchen scraps (poor chooks)
– Layers of Minerals
• Lime, dolomite, rock dust, soil and mature compost
Compost continued
2. Sheet compost
– For larger gardens
– Same layered ingredients directly on the garden
beds to form thick mulch layer
– Place vegie scraps under mulch onto soil –
earthworms will go crazy
– Similar to no dig garden
– Repeat annually
Compost continued
3. Green Manure
– Plant seeds and when fully grown either turn in
to the soil or cut down as a mulch layer
Or let the chooks in!
– Nitrogen fixing plants
Lupins, lucerne, fenugreek,
– Sorghum, wild bird mix
– Buckwheat
– Weeds (pre seed)
• Rock dusts
– Natural soil remineralization
• Si, Ca, Mg, P, S, K, Fe, Zn, Cu, Mn, Mo, C
– Lime, dolomite, natural gypsum, basalt, granite,
rock phosphate
– Work best the finer they are by increasing surface
– Minerals released slowly by weathering
– Sped up by organic (humic) acids and soil
microrganisms (malic and acetic acids)
Minerals continued
– These weak acids release the constituent
elements from rock dust into a usable soluble
– These elements are attached to soil colloids such
as humus and clay and accessed by the plant
through positive ion exchange with H+
– Work best when incorporated into compost
– Or incorporate into soil with the addition of
Minerals continued
• Natural Gypsum
– Often referred to as a clay breaker, much more in
the way of soil conditioner.
– Links on the website
37 advantages
5 key benfits
– These include: soluble source of Ca & S, improves acid
soils, improves soil structure, increased water infiltration,
increases stability of organic matter(sandy soil), helps
• Looking at commercial fertilisers one might
think the only nutrients are:
– Nitrogen(N), phosphorus(P) and potassium(K)
– These primary nutrients are important, but unless
we have a balance of all minor nutrients, trace
elements, carbon and other minerals, our soil
cannot be balanced and provide optimum growth
• The availability of the most abundant nutrient in the
soil is only as good as the availability of the least
abundant nutrient in the soil
Nutrients continued
Adding nutrients
• Well prepared composts will replenish humus,
minerals and nutrients and build a soil food
• The organisms involved in the soil food web
release nutrients to the soil and roots
• Use balanced organic fertilisers (like Organic
Xtra) as they contain a full range of nutrients
and are teeming with beneficial microbes.
Nitrogen (N)
• Nitrogen is largely responsible for healthy leaf and stem growth,
required to make protein in plants and is associated with
• Nitrate nitrogen (NO3) is the most readily available form of nitrogen
utilised by plants. It is also easily leached out of soils.
• Ammonia nitrogen (NH4) can be taken up by plants directly, but
since it is rapidly oxidized by bacteria to the nitrate form (the
nitrification process), it is usually in this nitrate form that it is taken
up by plants. Ammonia nitrogen does not leach from soils.
• Urea nitrogen (CH4N2O) has to be converted to ammonia nitrogen
(and on the nitrate nitrogen) by bacterial activity before it can be
utilised by the plant. There can be some losses in this process, e.g.
• Nitrite nitrogen (NO2) is toxic to plants. This is not normally a
problem because nitrite is quickly converted to nitrate by bacteria.
Phosphorus (P)
• Phosphorus is very important for root growth.
It also is crucial for producing flowers and in
the early stages of a plants life as it develops
roots and shoots
• Phosphorus is often present in soils in an
insoluble, unavailable form. Many factors
including temperature and pH affect the
availability of phosphorus to the plant.
Potassium (K)
• Potassium is needed for overall plant health. It keeps the
plants growing and aids their immune systems.
• Whilst nitrogen promotes soft lush growth, potassium
balances this effect to produce firm compact growth.
The two elements are needed in similar levels of
• Essential for the water regulation within the plant (turgor
pressure) as well as the movement of carbohydrates and
the creation of cellulose (Cell structure).
• Sufficient potassium is essential for flowering and assists
with creating sweet, firm fruit and helps ensure plants have
a good shelf life. Potassium is soluble in soils but moves
relatively slowly
By Tony de Vere
• Composted organic matter, or humus, will help give your soil structure. It
helps sandy soil by retaining water and it corrects clay soil by making it
looser. In all soils, it encourages beneficial microbial activity and it
provides some nutritional benefits. Humus is natures way of feeding the
circle of life.
• Adding organic matter will help replenish or "feed the soil".
• Organic fertilisers, made from plant, animal or mineral sources, release
their nutrients slowly, which means that plants can feed as they need to
and there is no sudden change in the makeup of the soil which might
harm the microbial activity.
• Adding rock dusts to create mineral rich soils and plants
By making healthy soil a focus at the start of making a garden, you will
have a head start on creating a sustainable organic garden.
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