Common Soil Types In Australia And How To Manage Them

Knowing the difference between the soil types found in Australia – and how to work with them – could make or break your next crop this season.

While most believe that soil is an essential part of plant growth, look no further than the magic of hydroponics – if you are able to provide the required essential nutrients like nitrogen and phosphorus, then soil isn’t required.

The earth provides a solid anchorage point for our plants, but soil shouldn’t be viewed with a “one size fits all” approach. Most gardeners are more or less familiar with the terms of soil aeration, soil drainage, soil pH and soil types – but what do they all mean?

Soil Type – All soils that share a certain set of well-defined properties form a distinctive soil type. This usually refers to the types of particles and materials present.

Soil Aeration – This involves perforating the soil with small holes to allow air, water and nutrients to penetrate through, allowing roots to grow deeply for healthier plant systems.

Soil Drainage – The natural process by which water moves across, through and out of soil via gravity. Surface drainage can purposely divert this too to dictate how much water the soil gets.

Soil pH Level – Lower pH values correspond to solutions which are more acidic in nature, while higher values correspond to solutions which are more basic or alkaline. Most plants prefer a pH level ranging between 5.5 to 7 on the scale.

The Three Major Soil Types In Australia

One way or another, the type of soil available to you in your garden, paddock or pasture will affect the plants that you’re trying to grow. However, you may be up against more than one soil type – and this often directly relates to the climate and landscape of where you live.

Soil is made when rocks break down and mix with plant and animal matter. The properties of your soil are largely determined by the amount of organic material it contains, as well as the type of parent rock it comes from.

In Australia, the three major soil types found include:

Sand – When you touch a naturally sandy soil it feels gritty in your hand, and that’s because the sand particles are comparatively large. When they come together, there are plenty of air spaces between the particles. This is why sandy soils are hungry, as they drain freely with the valuable nutrients washing straight through it. Sandy soil can also be a problem in high rainfall areas, as both the soil and any shallow rooted plants can quite literally wash away.

Clay – In comparison, the particles found in clay soil are tiny, making it tightly compacted and quite heavy. There’s very little air space, so they can become easily waterlogged with poor drainage. If you can create drainage through cultivation or racking the area, that will help your plants uptake the moisture and nutrients available. The density of clay soils will also help plants stay rooted, as there is little wash away with rainfall.

Silt – Silt particles are between clay and sand in size, but they can be difficult to wet when they’re dry – and they can be difficult to drain when they’re wet. With the addition of organic matter, silty soils are quite workable, and are usually soft to touch with a soap like texture. It’s usually a popular choice for pastures and veggie gardens, as you’re getting the best of both worlds when compared to clay or sandy soils.

How To Improve The Quality Of Your Soil

With a large range of pH soil kits now available in Australia, determining the qualities of your soil is relatively easy. A handful of these include:

Water Test – A tried and true method is to simply pour water onto your soil directly. If it drains quickly, it is likely to be sandy or gravel soil, compared to clay which takes longer to absorb.

Squeeze Test – Softly compress a handful of soil in your fist. If it’s sticky and stick to touch while remaining relatively intact, it’s clay. Sandy soil will instead feel gritty and crumble easily. Silty soils will feel smooth and hold their shape for a short period of time.

Settle Test – Add a handful of soil to a clear container with water. Shake well, then leave to settle for 12 hours. When you return, clay and silty soils will leave the water cloudy, with a layer of particles at the bottom of the container. In comparison, sandy soils will leave the water mostly clear, with the exception of a small particle layer at the base.

Acid Test – A normal pH reading is between 4.0 to 8.5, with the optimum range being between 6.7 to 7 for plants to thrive. pH tests are available for purchase at Bunnings or most garden centres in order to test the levels of acidity and alkaline in the soil.

Soil Test Kit – If you really want to get into the nitty gritty, a soil test kit can assess both pH levels and primary nutrients present in the soil (nitrogen, phosphorus and potassium). You’ll then be able to determine the exact conditions for fertilizing and other additions to your garden.

While the above methods are relatively quick and easy ways to essentially ask your soil what it needs – what do you do once you have that data?

If you’re looking to plant in a sand based soil, the use of plant probiotics will provide invaluable microbes and nutrients that can assist in soil regulation. Ultimately, you’re trying to protect against drought, frost and wind conditions, regulate pH levels, plus give the soil the head start that it needs in order to be at it’s best before new plants are introduced.

When in doubt, it never hurts to speak to a professional soil doctor. Bioweed are proud to work with their very own team of in house agronomists, so please contact us if you would like to discuss using plant probiotics or the overall health of your garden or soil.