Killer Compost

bewareComposters Beware !

I thought I knew composting pretty well, see my post ‘Here’s the Dirt on Composting’ at But I just read a post by Joe Lamp’l, who is the host and Executive Producer of the award-winning PBS television series Growing A Greener World, of about the dangers of using manures or hay from chemically sprayed fields. Who knew?!! But every gardener who grows edibles should be aware of this important wrinkle. It makes total sense, but it just goes to show you that we are poisoning ourselves slowly but surely. Go to Joe’s blog to read the results of doing all the right things – composting manures, amending the soil, mulching, etc., and see what happened to Joe’s vegetables when unknowingly he used tainted compost.  This is scary, as I live surrounded by farm fields and I know that the local farmers all use these herbicides.

Spray Residues

Used container of herbicide in farmer field ca...
Used container of herbicide in farmer field causes harzard (Photo credit: IITA Image Library)

Amazingly, spray residues from broad-leaved weeds can persist for a long time, from a couple of months, to longer than 3 years! The pathway goes like this; absorption of the herbicide  by the roots, the fodder or hay is fed to the animals, then is excreted as manure full of herbicide traces that is resistant to biological degradation when added to the compost pile.  The “cooking” of the manure in the decomposition process does not break the herbicides down, persisting into the compost that is carefully added as a soil amendment to nourish the soil. According to the US Composting Council, the molecular bonds joining these herbicide compounds can be resistant to the normal decomposition methods in composting.

Effects on Plants

Herbicide damage in wheat
Herbicide damage in wheat (Photo credit: CIMMYT)

Joe’s tomatoes were visibly affected with twisted and distorted leaves. Other effects – reduced fruit set, cupping of the leaves, and generally diseased looking plants.

Diseased tomato plant
Diseased tomato plant

The herbicide container should note in the directions that manures and fodder should not be used for composting, but who reads all the directions?? And does the farmer pass that information on to the hay buyer, or consumer?

What Can You Do?

So, how can you as a homeowner and compost maker and user, avoid these residues?

The traces can be present in hay, manures, leaf, and lawn debris. If an herbicide was used on your lawn to kill broad leaved weeds, then I would not be using any of the lawn clippings in my compost. In the future, I will be asking questions of the farmer that I buy my straw from, and will be checking out any leaf or manures that I put in my compost. A test to see if the herbicide residue is still present is very expensive to do, over $300 a sample, and the debris is not homogenous, so it is hard to test.

Composting Council

Weeds sprayed by a herbicide. Taken in Victori...
Weeds sprayed by a herbicide. Taken in Victoria, Australia in March 2008 (Photo credit: Wikipedia)

I wondered if these findings were new and again the composting council could answer my questions.

This is not new, scientists have been aware of this for a long time, and it is just percolating throughout the gardening world. Go to for a fascinating read on this topic. Multiple composting facilities have been affected and even had to close down because of tainted compost. A class action suit was filed against Dow, one of the big producers of these herbicides.

Well built composting unit
Well built composting unit

Chemicals are Everywhere

Nothing is simple anymore, even compost which I thought was pretty straight forward. We need to be more aware of the chemicals that are used around us, asking more questions, and contacting our local politicians about our concerns. Being a beekeeper has really brought this home to me with the increasing use of Neonicotinoids and the link to Colony Collapse Disorder. See my post on Colony Collapse Disorder

Swarm of bees in my apple tree
Swarm of bees in my apple tree

3 Replies to “Killer Compost”

  1. The persistence of herbicides in the environment long after their intended use has cause many problems. Both in the compost pile and in the landscape where they were originally used. It is just another reason to consider more organic solutions. When you look at the long term effects of herbicides – the chemical solution is neither easy or effective.

    1. I totally agree. Beekeepers in Maryland now want a central registry for all herbicide use to be established so bee deaths can be studied. The big chemical companies and agricultural entities are against this. I will be blogging about this issue also. We as consumers have to make our voices heard.

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