A Warning to Gardeners: Your Manure or Compost May Be Contaminated with Aminopyralid Herbicide

If you are a gardener and you use any composted manures or compost from an outside source (whether you buy them or get them for free), thinking that it’s safe, organic and full of goodness, THINK AGAIN.

Farmers and other sources of manure and compost often treat their land with herbicides, some of which are designed to not break down in an animals digestive system.  One such herbicide is aminopyralid, which is a selective, hormone-based, broad-leaf herbicide.  Aminopyralid is marketed under many brand names throughout the world and is used on hay, grain corn and grass crops to suppress broad-leaf weeds.  If unknowingly introduced into your garden or farm, the affects can be devastating.

Many farms use aminopyralid because it doesn’t break-down in an animal’s digestive systems.  This means that the waste produced by the animal (who eats hay or grasses contaminated with aminopyralid) also contains active aminopyralid, so the waste itself is herbicidal.  As such, farmers save money in material and labor costs by not having to reapply aminopyralid as much as other herbicides since the contaminated animal waste continues to spread the herbicide!

But the problem for small vegetable & fruit gardeners is that there is a great chance that composted manure and even mushroom compost that they might “import” into their gardens may be contaminated with aminopyrali.   Aminopyralid does not break-down in an animal’s digestive system nor is broken down by water or by composting the affected materials.  This not only means that your organic farm or garden is not organic, but it also can result in certain crops not growing, not producing properly and poisoning you with the herbicide even if the crop does grow and produce!  And to make things worse, aminopyrali can stay in your soil for years.

Mushroom Compost Poses Another Problem

Mushroom compost is not a safe alternative.  Since it is made with hay, it could be be contaminated with aminopyralid, as well.  Also, mushroom compost manufacturers often treat their compost with chemical, non-organic fungicide to inhibit the growth of mushrooms!  One of the largest buyers of mushroom compost is landscapers who use it as a top dressing for newly-planted lawns.  Since more profit is made from landscapers than gardeners, mushroom compost manufacturers will cater to them and use the fungicide in their product making it potentially hazardous for edible gardening use.

So the only way to know if the manure or compost you are using is contaminated with aminopyralidor or fungicide is to ask the source if the manure or composted is made with waste or hay that is contaminated with aminopyralidor or fungicide.  But unless you’re dealing with a source that you know is trustworthy, there is not a sure-fire way of getting clean, uncontaminated compost and manure.  If the source is profiting from selling the manure or compost, they aren’t going to want to lose the sale by telling the truth and if they are giving it away for free they also may not tell the truth since they need to get rid of the manure (which is why they are giving it away in the first place).  And if you buy your manure or mushroom compost from a reseller (like most home gardeners do) you will never be able to get any information because resellers simply do not know if their stock is contaminated or not – they merely buy in large quantities at the best prices they can get and then resell it.

So What Can You Do?

Unfortunately,  there isn’t much you can do.  If you can get affordable, truly organic, uncontaminated compost from a trusted source, then you are lucky.  But for the rest of us, we simply have to stop using any manure or compost from outside sources and produce our own compost.  And this can be a challenge because, as you may already know, materials compost down to only a small fraction of what they used to be.  As such, in order to be able to produce the amount of compost you need every year you often need more material to compost than you can get your hands on.

It sure is becoming harder and more expensive for people to grow their own food and eat healthier these days, unfortunately.


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