Brisbane has four main soil types: dark alluvial soils deep red loamy soils gravelly red and yellow loamy top soils over clay shallow gravelly soils
Northside Dark alluvial soils Dark alluvial soils Bald Hills, Brookfield, Eagle Farm, Fig Tree Pocket, Hamilton and Hendra Southside Dark alluvial soils Dark alluvial soils Bulimba, Fairfield, Hawthorne, Jindalee, Runcorn, Tennyson Northside Deep red loamy soils Deep red loamy soils Boondall, Bracken Ridge, Bridgeman Downs, Carseldine, Clayfield, Moggill, Nudgee Southside Deep red loamy soils Deep red loamy soils Chelmer, Corinda, Eight Mile Plains, Graceville, Kuraby, Lota, Macgregor, Manly, Manly West, Oxley, Robertson, Rochedale, Sherwood Sunnybank, Sunnybank Hills, Wynnum Northside Gravelly red and yellow loamy top soils over clay Gravelly red and yellow loamy top soils over clay 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 Southside Gravelly red and yellow loamy top soils over clay 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 Northside Shallow gravelly soils Shallow gravelly soils Albion, Ascot, Ashgrove, Bowen Hills, Chermside West, Fortitude Valley, Lutwyche, Mt Coot-tha, New Farm, Newstead, The Gap, Windsor Southside Shallow gravelly soils 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 residues 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 #1The 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 #2The 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 bacteria 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 garden pH 6-7.5neutral, suits most plants, maximise nutrient availability pH < 5acidic, most plants will not grow well and limited nutrient availability pH > 8 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 – (rainforest) Farmers and gardeners had always worked on these principles Justus von Liebig -19 th 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 – 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 Humus 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)
Minerals 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 area – 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 form – 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 compost
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 agriculture-5-key-benefits-you-should-know agriculture-5-key-benefits-you-should-know – These include: soluble source of Ca & S, improves acid soils, improves soil structure, increased water infiltration, increases stability of organic matter(sandy soil), helps earthworms
Nutrients 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 “WEAKEST LINK IN A CHAIN”
Adding nutrients Well prepared composts will replenish humus, minerals and nutrients and build a soil food web 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 chlorophyll. Nitrate nitrogen (NO 3 ) is the most readily available form of nitrogen utilised by plants. It is also easily leached out of soils. Ammonia nitrogen (NH 4 ) 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 (CH 4 N 2 O) 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. volatilisation Nitrite nitrogen (NO 2 ) 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 concentration. 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
Summary 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.