Our apartment complex was built 20 years ago on top of an old rail yard, so we decided last year that it would be a good idea to test the soil for heavy metal contamination. We wanted to make sure that we could grow our vegies and herbs without putting our health in danger.
Given that the Inner West of Sydney, where we live, generally has high rates of soil contamination, and our location was until recently surrounded by light industry, we didn’t have high hopes of good results – so imagine our surprise when the tests showed very low levels of all the metals tested for!
In fact the amounts of some metals, like copper and zinc, were so far below the acceptable maximum that we weren’t quite sure we were reading the table correctly. Could it really be true that we only had 80 milligrams per kilo (mg/kg) of zinc, when the acceptable level was as high as 7,400 mg/kg?
To be fair on us, we’re not total idiots; just slightly mathematically challenged (well, I am). Plus the table of guidelines for soil contamination that we compared our results to is confusing to us non-scientists. It includes guidelines from other countries, not just Australia, and in some cases they are radically different numbers.
It took us, well, almost a year to email the VegeSafe team at Macquarie Uni and make sure our take on the results was correct. It is. ‘Your soil is very clean’, they told us, with ‘very low concentrations across the board’. We told them it would have been nice if they’d said that when they originally emailed us the results, instead of just bamboozling us with tables. They said they’d take our feedback ‘on board’.
Anyway, over the past ten months between when we took the samples, and when we got off our bums to contact VegeSafe, we just gardened in the raised beds. Well, mostly. We couldn’t resist making pumpkin soup from this butternut that had self seeded from the worm compost. And now we know that we weren’t poisoned by it – phew 🙂
Soil testing from VegeSafe is a free service provided by the Faculty of Science at Macquarie University. They test soil from anywhere in Australia and provide links to advice on what to do if you have contaminated soil.
If you are concerned about what heavy metals could be lurking in your back yard, it’s easy to find out. You just sign a consent form, dig up some soil samples from 5 locations in your garden, post them off (they are a bit heavy, you need a ‘cricket ball size amount’ from each patch), and wait for the results. Hopefully, as for our community garden group, your fears will be laid to rest. Happy gardening.