Archive for Downsizer For an ethical approach to consumption
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Hairyloon
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Rubbishy soil.I've just cleared a section of my garden that I had been avoiding. It was variously full of rubble, litter, scrap metal, litter, twigs, rotten wood and litter. Also a couple of car batteries.
Underneath all that, the soil looks to be quite good, but I am wondering if I should be worried about growing food in it because of contamination... not that anything that I've mentioned gives me any real cause, except perhaps somethihng in the paint on some of the wood.
Any thoughts? Other than sending some off for testing, which is not something I am likely to do.
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vegplot
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Car batteries would give me cause for concern if you're planning on growing veg.
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Hairyloon
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Car batteries would give me cause for concern if you're planning on growing veg. |
Why? The lead or the sulphates?
The lead is contained and the sulphates are mostly soluble and will probably have been mostly washed away. The insoluble sulphates should still be in the battery with the lead.
That isn't meant to be dismissive of your point: it was largely the batteriess that led me to wonder, but as indicated, I've decided they're not a worry.
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onemanband
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Re timber and paint, not the batteries
I wouldn't be too concerned - or rather I wouldn't dwell on it. Most urban gardens are probably 'contaminated' with paint from fencing, garden furniture, the house, DIY projects, etc.
I'd top with a few inches of known good soil and you'll have forgotten in a few years (unless your hair starts falling out  )
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Hairyloon
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Re timber and paint, not the batteries
I wouldn't be too concerned... |
Mainly lead and sulphuric acid.
Some of the acid has leaked, but as i said: I think it should be sufficiently diluted by now to be nothing to worry about...
If somebody knows better, do speak up... 
H2SO4 (weak solution)
If it ain't strong enough to dissolve the carrots you are growing in it, by the time you've washed, peeled, cut and boiled those carrots - it ain't going to be strong enough to dissolve you !
Hairyloon
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Oh, hang on... there will have also been lead sulphate in the solution won't there?
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James
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lead is surprisingly hard to take up by plants. So even if it is there, it wont move from the roots into the aerial parts of the plant
The risk to you is from root crops: soil particulates taken into the outer layer of spuds, carrots, beets etc...so stick to above ground (fruiting) crops: legumes, curcubits, tomatoes.
I'd perhaps be more concerned by the wood: except for the wax based stuff you can buy now, wood preserver is one of 3 things: creosote (or equivalent tar product), tri-butile tin (TBT), or copper arsenide. All these work by killing microbes & fungi really effectively. Tin and copper are also phyto-toxic. So plants could have problems growing there (question: how was the plant growth? overgrown? or less than elsewhere? this is important).
If in doubt, I'd be tempted to do a sacrificial crop of something like annual rye grass. Then once you've harvested that and taken to a municipal green waste facility, work hard at improving the environment for the soil fungi & bacteria by adding heaps of compost. You'll soon know if there's a problem with lead, tin, copper or arsenic because organic matter wont rot down and worms wont thrive.
If this is the case, use it for ornamentals. If the organic matter rots and worms thrive, use it for food.
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dpack
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tbt is the one i would worry about ,a catch crop of leafy things (coriander and spinach perhaps) to dig up and dump in a quiet corner might be sufficient to clean most domestic contamination.
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Mistress Rose
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That sounds really sensible James. Useful to have a man like you on the forum.
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Hairyloon
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Put that way, I think I might see how the dandelions get on with it this year.
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Slim
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Some great advice going down in this thread.
My main concern with heavy metals in soil is dirty produce and dirty hands. You are at a greater risk of ingesting lead from the contaminated dirt on the food and on your hands than you are from the plant matter itself. As James said, the higher up the plant you go the less lead will make it through. Contamination will be highest in roots, then stems, then leaves, and finally lowest in fruits. So squash, etc, is fine, just wash it off well.
In terms of phytoremediation (fancy word for growing plants on contaminated soil and then removing them from the site to dispose of said contamination) it can take [i]years and years[\i] of doing that to actually remediate a site. It's very species specific and contaminant specific. With heavy metals the plant matter definitely has to be removed. With organic contaminants the plant and its associated microbes can sometimes do a few good tricks of breaking them down, but sometimes not (sometimes they even make the chemical more dangerous!). Sunflowers are often used.
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LynneA
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What about planting some comfrey?
Their roots will draw the minerals out from even deeper than the dandelions, then discard the foliage.
Know anyone working at a secondary school or uni who could run a chemistry test on the soil for suspect stuff?
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