Mouthful

What in the world are you eating?

The second winter garden

18 August 2010 | 14:41 - By Phil Lees

As I mentioned a little earlier, my backyard patch has been aseasonal this winter. Rather than the bleak harvest of cabbage from the previous year, this season promises a voluminous crop.

My tactic has to plant whatever worked last year alongside heirloom vegetables that are nigh on impossible to buy at a reasonable price. This somehow breaks a golden rule of backyard vegetable gardening: if you’re not doing this for survival, only plant what you like to eat.

To be sure, I have planted a full court press of brassicas but in a wider range of varieties than last year: frilly leaves of red Russian kale, purple cabbage, Chinese cabbage (wong bok), Calabrese broccoli, a commercial looking variety of cauliflower that was on sale at my local supermarket and ruby brussel sprouts.

I planted twice as much beetroot as the previous year and am being repaid handsomely. I’ve planted 'chioggia' that grows with alternating white and pink concentric rings, 'golden' that promises yellow flesh that does not bleed, and 'blankoma' that grows roots that are a shade of bright white. A few messy rows of the higher yielding 'globe' beetroot take up the rest of the patch, destined for more bottling.

Filled with an uncharacteristic bout of wintertime hubris, I’ve also decided to renovate the whole patch and build the sort of garden beds that grace the screens of many a garden show: four beds constructed from the old redgum stumps from beneath my house and thick slabs of redgum to replace the CCA-treated pine slabs that currently holds the dirt in place.

While there is much talk on the dangers of treated pine use in garden beds, my decision was based on price: each redgum sleeper was $2 a piece more than the equivalent pine, so I thought why not?

“CCA” stands for “copper chrome arsenate” and is shorthand to say that the pine planks were treated with the chemicals to retard fungal growth and deter termites. An untreated pine sleeper might last a few years in the ground; a treated one a few decades.

The research into the effects of CCA treated pine on garden beds shows that it is safe. In a review of the research, the CSIRO states:

A number of studies have shown that CCA is not absorbed into above-ground food crops such as grapes, tomatoes and cucumbers. There are, however, some reports of a slight increase in arsenic content in root crops such as carrots and beets grown against treated timber, although the arsenic is in a safe organic form and most of it is removed with peeling.

Any concern can be eliminated by growing these vegetables more than 100 mm from treated timber garden edgings or by lining the edgings with plastic. This has the additional useful effect of reducing soil contact with the wood, which could further extend the wood's life.

Further, if the arsenic is released from the timber, it is in a relatively safe form. At least for beagles and sheep:

Ingestion studies with animals have shown that this greatly reduces its mammalian toxicity. For example, no evidence of toxicity was found after beagle dogs were fed 10 grams of CCA-treated sawdust per day for five days in food. Seventy percent of the arsenic passed with wood through the faeces. The rest was expelled in urine, having been extracted from wood in the stomach. The bulk (85 per cent) of the urinary arsenic was detoxified to dimethylarsinic acid.

In another experiment, researchers in New Zealand found no abnormalities after sheep and calves were fed 454 grams of CCA-treated pine on one occasion, or 113 grams per day for 25 days.

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Comments (4)

21 Nov 2010 9:02 AEST

Pete

From:

Misleading comments on CCA safety

I think the authors comments on the safety of CCA are misleading. For a start, CCA treated timber has been banned for domestic use in Europe and is being phased out in the US. Do you really think these bans are for no reason? The grape industry in Australia is recommending the removal of CCA treated timber from vineyards because of soil contamination. Also, short term studies on animals are cited, but overlook increased cancer risk from arsenic exposure and long term effects of chromium toxicity

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10 Sep 2010 20:00 AEST

landscape architecture sydney

From:

landscape architecture sydney

If you need any assistance regarding landscape designing tips then we will be glad to serve you.

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20 Aug 2010 10:56 AEST

Ivy Hornibrook

From:

Vegie bed timber and pots

Hubby built our garden beds from retired railway sleepers. They'd been treated but not by CCA, and so we deemed these safer for growing our own food. We're also trying to do things as organically as possible, and although I haven't checked my facts, common sense tells me CCA pine may not conform to organic principles. We haven't been as rigorous however with some lovely barrel-shaped pots for our herb garden so it's good to know above-ground crops aren't affected.

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19 Aug 2010 11:17 AEST

Dave

From:

CCA

Yeah, I went through the same issues when building my garden, but opted for treated pine for price reasons. Also, I didn't want a permanent garden - something that'll last 5 or 10 years will be good, by then I'll probably want to change it or I will have moved somewhere else. Loving the blog, keep it up. D

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About this Blog

A blog about what the world eats, when and where it eats it, and why it matters to us all. Only much less ambitious than that sounds and with more excruciating puns.

Phil Lees grew up in rural Victoria, the first generation in his family to not have lived on the farm and thereby not slaughter their own meat.

In 2005 he moved to Cambodia and started the nation’s first food blog, Phnomenon.com, named after the best pun that he has ever made. It turns out that Cambodian food is delicious and unlike the warnings in most guidebooks, is not likely to kill you with any immediacy. Gridskipper called him a “national treasure”. Lonely Planet’s Greater Mekong guide called him “the unofficial pimp of Cambodian cuisine”. The New York Times laughed at a funny hotdog he saw.

Phil makes a mean sausage, a hoppy pale ale, a modest laksa. He owns three barbecues and is in the market for a fourth.

 
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