Contaminated Soil

Have your soil tested by specialist engineers if you suspect heavy metals in the soil.

Testing Soil Before You Buy:

If you are in the fortunate position of being able to buy a property, you should test it before you buy. Make sure you test in several areas, especially boggy or low lying areas where contaminates may collect. The National Association for Sustainable Agriculture, PO Box 366, South Sydney, NSW 2000 or Organic Farming and Gardening Society of Australia, GPO Box 2605, Melbourne, Vic 3001 may be able to provide contacts for professional soil testing. Always try for free service and advise from Government bodies such as Department of Agriculture first. You contacting them helps ensure their funding, and keeps them available and accessible to a wide range of people.

What’s Toxic to Ecosystems?

Chemical tests on suspect soils will break down the chemistry into known compounds and elements. Chemical tests will reveal if there is arsenic, or heavy metals etc. But the detection of toxic elements by chemical methods

  • may not indicate whether the elements found are in a form that will be absorbed by plants and organisms or in a form that is harmful
  • will only reveal what they are designed to find – and other toxins may go undetected
  • won’t tell you when harmless elements are interacting to produce something hazardous nor
  • when two toxic compounds are neutralising each other.

At the CSIRO (Australia Government Science Research body) they are developing eco-toxicity tests as well as chemical tests. In eco-toxicity tests the soil is tested with algae, seed germination and worms.

Worms are a good indication of toxicity. “Worms share many metabolic pathways with humans. Thus the effect of soil pollution on earthworms can provide a good indication of potential harm to terrestrial ecosystems and to human health.” [ECOS Summer 1995-1996]

Identify the source of contamination.

Sources of contamination are most likely air, water, some sites may have been areas with chemical dumping (land fill).


Also consider the water that is coming onto the property, in normal rains and during flood. Identify potential contaminates upstream or uphill from your site, the chemicals which water can absorb are a threat to your plants as they too absorb water-soluble chemicals.


If you are living in area rich in red lichens then the air is quite clean. White lichen and conifers indicate fairly clean air. Some toxins that enter the site by air are not water soluble, they may be particles that are more a health hazard to people’s and animal’s lungs (by breathing the particles) than through eating the plants.

Imported materials

Sometimes the chemicals brought into the site are most hazardous, these include Round-up which is touted by many as not dangerous to the environment but contains a surfactant which kills aquatic animals and also contains potentially cancer-causing agents. Other imports are horse manure from horses that have been de-wormed. Mulching material such as coloured paper is usually safer to use as mulch than as compost. Remember that composting concentrates minerals and nutrients. If you are unsure, spread the material about and keep it covered so that any particles will not cause residents harm.

Will contamination recur?

Decide if the source of contamination is coming via the air and will be a long-term problem (a nearby orchard with toxic sprays, a lead smelter, etc.) or was it an accident some time ago (oil spill, mining disaster, fallout from old smelter).

If you are confident that contamination will not recur you should move to the next step to rehabilitate the soil.

Recycled Tarpauline Gardening