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Soil - 101

Updated: Nov 16, 2021

Healthy soil means healthy plants


And it’s important to get to know your soil before you start putting plants into the ground! Get to know it by looking, feeling and smelling.


LOOK - What can soil colour tell you?

Black soil

indicates organic material and fertility but can also signal poor drainage.

Dark brown, red and tan soils

colour comes from iron and aluminium oxides. They have organic material and provide good drainage.

Pale and whiteish soils

occur in areas of high rainfall and are low in nutrients

Yellow soils

​generally have a decent amount of organic material but become waterlogged easily and leach nutrients

Green, blue or blueish grey soils

worst, low in organic matter, poor drainage and are prone to compaction





SMELL - What can the smell of soil indicate?


Smell your soil to check its drainage. If it smells fresh, like walking through a rainforest, it means that it is draining well. If it wasn’t draining well, it would be anaerobic and smell bad, like rotten eggs.

FEEL - Get your hands dirty!

Best soils contain a mix of silt, clay and sand and are known as loam.

If you wet some of your soil in your hand, the sand feels gritty, the clay feels slippery and the silt feels like moist talcum. You can assess this with a simple ball and ribbon test:


  • Scrape back any mulch from your sample area, dig down about 4cm of soil then take a small sample (about a trowel full), removing any twigs and rocks. It can be good to sample various spots in your garden as soil can vary.

  • Put each sample in its own container.

  • Fill a bucket with some water.

  • Grab a handful of soil and moisten it by dripping some water over it.

  • Try to roll it up into a ball. Try rolling the ball into a ribbon.

  • Lastly, try ‘bending’ the ribbon.

Unable to form a ball? This is typical of sandy soil.

Rolls into a ball, forms a ribbon and bends easily? This is typical of soil with a lot of clay in it.


Rolls into a ribbon but breaks when bent? It’s a loam, with a good mix of clay, sand and organic matter. This is probably the best soil for growing a wide range of plants


Common soil problems + remediation tips


Too much sand

  • The soil will be well drained but won't hold a lot of nutrients

  • Add compost or aged manures to improve soil structure, water holding capacity and nutrient content

Too much clay

  • The soil will be poorly drainage and high in nutrients

  • Consider applying gypsum if you have clay soil to help with drainage

Too much silt

  • Soil will be hydrophobic (repel water) and prone to erosion

  • You may want to consider treating soil with a wetting agent from your local garden centre


Other useful tips


  • Water your garden with a spray nozzle to avoid compacting soil from any concentrated water streams

  • Organic matter needs to be replaced as plants absorb nutrients, especially in productive gardens. Spread compost and aged manure over your garden before mulching to encourage worms, important for breaking down organic matter and aerating the soil.

  • Mulch to help retain soil moisture and add valuable organic matter to your soil. Straw based mulches, such as pea straw, break down quickly and are ideal for vegetable gardens.


Information sourced and adapted from:

Gardening Australia

Sustainable Gardening Australia





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