The soil of your property has a large bearing on the types of trees you can successfully grow and on what you might need to add to your soil when gardening. In this article we will take some technical measurements of Indooroopilly’s and Taringa’s soil and try to put them in simple terms for their effect on your gardening.
The most important factor in Indooroopilly and Taringa is probably the shallowness of the soil. There simply isn’t much there. CSIRO maps suggest there is only 1-1.25m of soil in which tree roots can grow, and if your house is on a hilly site it’s likely to be even less.
What’s more, the soil that is there isn’t very fertile. It’s made up of about half sand which doesn’t hold soil nutrients very well and can’t hold water. In more built up areas and closer to the Brisbane River it’s up to 80% sand.
To increase fertility topsoil can be imported. Good quality garden soil from a landscape yard will have sufficient nutrients and have better properties than native Indooroopilly soils.
Also, you can add a thick (~100mm) layer of woodchip. Woodchip helps supply nutrients to the soil and also improves the environment for soil microorganisms. They in turn give your soil better structure.
Fertilising with Nitrogen is fraught with problems as it tends to acidify your soil. On the other hand, Indooroopilly soils really can do with other nutrients added. We tend to recommend a good general fertilizer low in Nitrogen as the mulch will add enough of it when it breaks down. It will also do wonders for the soil’s structure.
Soil structure refers to how well soil holds together in clumps. That’s important because the clumps allow spaces for air and water to seep into the ground, and trees and plants need both at their roots.
That brings us to compaction. Indooroopilly soils are often compacted. This may be because of acid sulfate soils in the lower lying parts of Taringa and Indooroopilly (on the eastern sides of both suburbs) or, more likely, from sodicity. Sodic soils are high in Sodium (not to be confused with saline soils which are high in sodium chloride). The best additives for sodic soils are Gypsum and mulch.
The best treatment for trees in compacted soils is vertical mulching. Vertical mulching is mixing grains of a large size into the soil in cores which we remove from your soil. If you think your ground is compacted we recommend you contact us for an assessment of your property’s soil.
The final issue with Indooroopilly’s soil is the acidity of the soil solution. It is quite acidic with a pH of around 4.9-5.5, except on the eastern side of Indooroopilly where it drops to around 4. Adding lime to your soil will greatly help increase the pH of your soil, but it does take time. Alternatively, you can grow acid-loving plants such as Azaleas or, even better, local Australian native plants and trees which are suited to the soil type.
Here is a list from Paten Park Nursery:
Small trees native to Indooroopilly and Taringa:
creek lilly pilly Acmena smithii Edible fruit, good drainage
foambark tree Jagera pseudorhus Pink flowers
native guava Rhodomyrtus psidioides Its small fruits attract birds
yellow boxwood Acronychia laevis rainforest tree of Mt Coot-tha foothills.
Larger trees
Pink bloodwood Corymbia intermedia Beautiful bark, closely related to the larger gums.
Blue quandong Eleocarpis grandis Attractive blue fruit, attracts parrots.
A final suggestion for selecting the trees you grow around Indooroopilly and Taringa is to get rid of those weeds. Chinese elms are particularly common in the area, and there are plenty of cocos palms that still need removing. Both are invading local bushland and end up effecting our beautiful native fauna.
Is anything in Garden Soils of Indooroopilly and Taringa wrong? We love correction. Please let us know here.
References
- Soil and Landscape grid of Australia
- BCC interactive mapping
- Paten Park Nursery