When I first heard about this little problem of pesticide residue in the compost, I thought it wouldn’t affect me since I don’t use pesticides anywhere in my garden. Oh boy was I wrong… Turns out that if you use manure in your compost (and I’ve gotten some from the local stables on occasion) you need to worry. If the horses (or cows) grazed on hay that was sprayed with one of these chemicals, they are in your compost.
Another thing to worry about! In the past two years farmers and gardeners in the UK and US have experienced the unintended effects of a powerful herbicide called aminopyralid, sold by Dow Chemical under the brand names Merit and Forefront. This herbicide is used to control weeds such as thistle, knapweed and yellow starthistle.
The problem is that aminopyralid survives the digestive systems of animals pastured on land sprayed with it, as well as compost piles made from their manure. Most other herbicides break down eventually, but this stuff sticks around.
An organic farmer using compost contaminated by aminopyralid could lose crops and organic certification for years. If that isn’t enough to worry about, two other nasty herbicides, picloram and clopyralid have also contaminated compost piles around the world.
But what about us backyard gardeners? How can aminopyralid effect us? I’m fond of using a bit of horse manure in my compost pile. It’s free for the taking and helps heat up the pile. But if the horses were fed hay grown on land sprayed with aminopyralid I could lose my veggies, particularly tomatoes, lettuce and legumes which are highly susceptible to this chemical.
There’s a lot more info over there, so go read and see how you can prevent this issue in your own garden.