The currently suspended herbicides based on Aminopyralid will be working their way through the food chain to end up on our allotments and gardens for years to come. Assuming the suspension becomes permanent and the farmers stop using their stocks, the problem of contaminated manure will still be around until 2012 or even later.
Testing for Aminopyralid Contaminated Manure
If you suspect your manure is contaminated, the way to test is to start a few tomato plants off and transplant them into a compost with 50% manure. Make sure the manure is chopped finely or shredded and well mixed.
If the plant shows the distorted leaves typical of hormonal weedkiller damage then you know you have the problem.
From what I gather people are being charged over a hundred pounds for a test that basically consists of growing a tomato in the manure and seeing what happens.
What to do if you have Aminopyralid Contaminated Manure
Having discovered you have a load of manure that’s contaminated with this persistent hormonal weedkiller, your next problem is what to do with it.
Legal Redress for Contaminated Manure
Now it has been suggested to me that you might have legal redress against the supplier of the manure and could return it to them. But the supplier of the manure most probably had no idea it was in there. It could have entered the manure directly through cattle or horses grazing on grass sprayed with Aminopyralid or via silage or in the hay or straw.
If people start suing farmers and stables for damages caused by manure, often sold at a price that covers the cost of delivering it, they are either going to stop supplying or put the price up to cover possible liabilities and insurance. Madness. And you’re probably just suing someone who is as much a victim as you are.
The problem with returning manure to the supplier is that you are just passing the buck back to someone probably blameless who has done you a favour. Handling the problem directly makes more ecological sense as well.
Decontaminating the Manure
We know the Aminopyralid is eventually broken down by microbial action in the soil and this is what we need to encourage.
If you have a manure pile and just leave it stacked, or even turn it over, the relative lack of the right microbes means it could be two or three years before it becomes safe to use.
The best way is to select a patch of ground and spread the manure a few inches thick on the surface and then rotovate it well into the soil. Don’t bother sowing anything in there because it could be counter productive as the chemical will be taken up and bound to the lignin in the crop. When composted, the problem cycle starts again as the Aminopyralid releases.
After a month, rotovate again. And again, and again and again. After six months or so it’s probably OK and worth testing with tomatoes or potatoes grown in the soil. Don’t just test soil from one place. Ideally test five points – imagine a number 5 on a dice.
What we are seeking to do is to ensure no lumps of contaminated manure remain and the microbes have had chance to do their job thoroughly. That’s why multiple rotovations will help. If you don’t have a rotovator and can’t borrow one, then chop up the manure with a spade and fork it into the top six inches. Turn it over with your fork each month, incorporating any weeds so they rot down as well.
We’ve won a battle against this, if not the war and we need to remain vigilant for at least the next 4 years. Now we know what the problem is and how to deal with it, at least we can keep on growing.