George Monbiot has a piece in the Guardian (UK) providing a look inside a troubling pattern observed by gardeners there: manure applied to their gardens appears to have been sickening their plants rather than nourishing them. The key suspect is a recently release herbicide called aminopyralid, used on pastures to kill broadleaf weeds while sparing desirable forage grasses, both for grazing and for cut and stored hay ('forage' or 'silage.')
The problem is that this synthetic plant hormone is very stable in the environment: it persists in soils and compost for two to three years (at least), and can pass unaltered through the digestive tract of grazing livestock to persist in their manure. It then becomes a problem for farmers to make use of all their stock's affected manure in ways that don't accidentally poison other non-grass plants they are trying to grow - vegetables, beans, clover, whatever. Each farmer applying this product has to learn and understand this persistence issue, then manage their animals movements (in both senses) to avoid collateral damage by friendly fire from the chemical weapons they paid for to help out their pasture grasses.
Now, a pinko greenie hippy radical ecofascist might point out that there are good, proven ways to maintain healthy pastures that don't involve using chemical weapons like these. If you've read Michael Pollan's book The Omnivore's Dilemma (also available in a kids' edition) then you know about William Salatin's Polyface Farms in Virginia. Salatin is a one-man organic green revolution and soil improvement guru. He rotates grazing cattle, then hens, then some growth time for each patch of pasture, all without any whiff of synthetic chemicals. But don't let me mangle his great ideas - read them for yourself.
Anyway, I found that aminopyralid is approved for sale in Canada under the Dow Agrosciences trademark "Milestone"(TM); this Ontario OMAFRA page on aminopyralid lists the precautions farmers need to take in its application, including managing where livestock goes after grazing on treated pastures.
Here's a June 2011 report from Alberta's organic farmer's association cautioning of this hazard for Canadians.
I know there are some organic farmers here in Ontario. Our local farmer's markets at The Brick Works and Withrow Park host a few, and The Big Carrot carries produce and meat from several. What's troubling about this latest chemical warfare friendly fire incident is not whether these compounds are harmful to human health - they aren't known to be -- but that they are so stable and persistent that animal manure can't be trusted for use on beds intended to grow anything other than grasses. This then becomes an issue for anyone buying manure for home gardens or for small scale vegetable farming.
We now need to check the provenance of every bag of manure, as well as every bale of hay to be fed to farm animals, as these chemicals can pass from treated fields via hay, through the animals' digestion, into their own manure. Whether they range around leaving manure on their farmer's own fields, or their manure is collected and later spread on the farm or sold outside, these persistent herbicides can just keep going along for the ride and attacking plants wherever the manure is finally applied.
Thus home gardeners now have to become vigilant about what may be in the manure they buy to mulch or amend their garden soil, whether for vegetables, flowers, shrubs or trees. All are prone to attack by these chemical warfare agents. They become collateral damage in the civil war on weeds, yet another case of friendly fire in our ongoing chemical warfare on our own fields.
But hey, at least these new weapons are a lot less worse than last generation's chemical weapons, where the Agent Orange organochloride compound 2,4,5-T was sold for widespread in Canada use to kill weeds in non-crop settings like fencerows, power line rights-of-way, CFB Gagetown, etc. Then it was shown to be a carcinogen and to commonly bear as a contaminant the highly toxic TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), leading to its withdrawal for crop use in the US in 1970 and general ban in 1985 in the US, Canada, and worldwide.
Canadians who believe they may have been exposed to 2,4,5-T (and likely thus to TCDD) via their work should contact the WSIB Occupational Disease Information line.
