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Latest News on Killer Compost

Posted by okiedawn Z7 OK (My Page) on
Mon, Jan 28, 13 at 10:11

For 5 or 6 years now, I've periodically mentioned the issue of killer compost here on this forum, particularly at this time of year when we have new members who may be obtaining compost, manure and other organic matter (including hay or old stable bedding) to be used to enrich their soil. It is time to talk about it again.

For anyone not familiar with the issue of killer compost, the term applies not just to compost, but also to hay and manure. An issue since the very early 2000s, killer compost (which contains residues of certain herbicides that persist for years) can ruin a garden and make it impossible to grow much of anything in that garden soil for several years until the herbicide residues break down and go away.

You can bring these herbicide residues into your garden unwittingly by using hay, straw, compost, municipal compost, composted manure or even purchased compost or manure that contain these herbicide residues. To be clear, these residues persist in some cases for several years, and they survive going through the animal's digestive tract, and they survive being composted. They survive in high enough levels to ruin your garden by killing your plants or by stunting them so badly that they do not produce a crop.

Mother Earth News has long been a leader in the effort to educate farmers and gardeners about the risks involved in inadvertently contaminating your garden soil with these herbicide residues.

The latest issue of Mother Earth News has an outstanding article about Killer Compost. I have linked it below.

I protect my garden by never bringing in any outside material if I am not fully confident it is not or cannot be contaminated by herbicide residues. Based on this latest MEN article, maybe I'm not keeping it as safe as I think I have been because it appears that animal feed even can be contaminated with these residues.

I encourage you all to read the article and then we can talk together about questions it brings up.

I am headed outside in just a minute to work on New Garden Area #2, north of the barn-style garage, where I will be using a large number of three-year-old bales of hay to build new beds. I have watched them slowly decompose in place for several years and have observed that broad-leaved weeds grow right beside them so I am pretty confident this hay does not contain those pesky herbicide residues, but after reading this article I feel like I may not use old hay any more after this last batch is all gone because the risk of getting some that was sprayed with a herbicide is too great.

FYI---it still is safe to use alfalfa hay in your garden because it is a legume and cannot be sprayed with the type of herbicide that causes the problems because those herbicides are used only on grasses. If you sprayed alfalfa with them, you'd kill the alfalfa.

One of our neighbors here told me last year she felt like she had inadvertently contaminated her garden with these herbicide residues and was going to have to start a new garden in a new spot on her property. I feel terrible for her, and hope that the rest of us can avoid having the same thing happen to us.


Here is a link that might be useful: MEN Article on Killer Compost

Follow-Up Postings:

RE: Latest News on Killer Compost

thanks so much for this information dawn because i feel that my dh has been using this stuff in our veggie garden. i printed him a copy of both articles.

RE: Latest News on Killer Compost


I had some damage that I though was caused by herbicide a few years ago. That area did not produce that year, and has been sub-par since. I grew okra and Armenian cucumbers in it last year and they did fair. ( it is only a small area, one row about 25' long out away from the other growing areas.)

After I found that I had a problem of some kind I put in what I call my "Experimental" garden. It is only about 50 sq. ft. That I test all incoming organic matter in. I do not test the shreaded leaves and oak shavings becaus I know where they come from. I may stop using anything other than the leaves and shavings.


RE: Latest News on Killer Compost

Jessaka, You're welcome. I hope the info is useful.

Larry, The issue of killer compost is one reason I have come to rely on chopped/shredded leaves so much. People here in our local area often ask me if I want old hay or cow manure from their barns and I mostly (and regretfully) say no because I know they use some of these broadleaf weedkillers in their pastures or because they buy hay and we have no way of knowing if the purchased hay was sprayed with any of these persistent herbicides.

I have used Black Kow cow manure for as long as I can remember and have no intention of giving it up. However, I do test each bag by trying to sprout beans or peas in it before I add it to growing beds or containers. Testing only takes a short while and it is worth it to have the peace of mind of knowing I'm not contaminating soil I've worked so hard to improve.


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