Herbicides In Compost

Herbicides in your compost pile can cause problems when the compost is used on your garden.

Where do the herbicides come from? If you use grass clippings in you compost pile, and your lawn has been treated with weed killer, there could very well be herbicides present.

While manufacturers of lawn treatments have claimed that they are safe for humans, they could be detrimental to your plants.

Another source of herbicides comes from horse manure. If the horses have eaten hay that was treated, herbicides could show up here as well.

So be careful when adding materials to your compost pile and be aware of the potential for herbicides.

Here is one person’s experience:

I purchase locally grown hay and feed it to my horses. Horse waste is put in my compost pile, along with lawn and yard clippings. Last year, we used the compost on our vegetable garden. As the plants came up, I noticed something very wrong. Most of my vegetable plants were extremely deformed. The potato plants resembled ferns, with the leaves twisted and the stems clubbed. Tomato and sunflower blossoms and stems were almost unrecognizable, they were so abnormally shaped.

I sent plant samples to the state food lab in Twin Falls. The chemist there told me that the damage was indicative of that caused by a class of herbicides now commonly used on pastures, roadsides and hay fields. These herbicides are clopyralid and aminopyralid and their related compounds. According to an Ohio State University fact sheet, clopyralid, is sold under the trade names Reclaim, Stinger, Transline, Confront, Lontrel, Curtail and Millenium Ultra.

Clopyralid is very persistent in composts and manures and is largely unaffected by the composting process—plants in the bean family, the potato/tomato family and the sunflower family are very sensitive to this herbicide. It can stunt these plants at levels in compost as low as 10 parts per billion! Since the level of clopyralid on grass the day of application is 10,000 to 50,000 ppb, even a small amount of contaminated material can cause major problems.” Go to http://ohioline.osu.edu/aex-fact/0714.html to check these facts.

Idaho Mountain Express: Beware of herbicides in compost – July 6, 2011