ASK Jeff: The Rodale Institute’s farm manager, Jeff Moyer, answers your hardcore farming questions

We would like to include grass clippings from a local landscaping firm in our composting operation. Should we be worried about herbicides?

Posted August 17, 2004

What Jeff brings to the table

Jeff Moyer, who’s been the farm manager here at the 333-acre Rodale Institute research farm for more than a quarter of a century, receives lots of mail from farmers just like you asking for advice. Jeff’s hands-in-the-dirt experience over the past 26 years has run the gamut from refining the farm's cover cropping and crop rotation systems (including managing 270 acres in a rotation of corn, small grains, hay, and edible soy beans for a Japanese market) to overseeing The Rodale Institue Farming Systems Trial®, the world’s longest running side-by-side comparison of organic and conventional agriculture. We thought it would be fun and informative to share some of these farmer-to-farmer exchanges, and Jeff’s practical wisdom, with our readers … and we’ll be doing it on a regular basis.

Got a question of your own? Send it to Jeff at:

Dear Jeff,

I work at the the Regional Food Bank of Oklahoma. We currently have a composting area at the food bank, but we are looking at expanding it and starting to take in grass clippings from a local landscaping firm.

We are concerned because some of these lawns would have had pre-emergent and other herbicides used on them. We wanted to know what your opinion is on how this might affect our compost. If you have any research or web sites that you can refer me to so that I can do future research on this matter, it would be very helpful. Thank you in advance for your time and help in this matter.

Casey McKinney
Regional Food Bank of Oklahoma
Urban Harvest Marketing and Development VISTA

Dear Casey,

Here is what I know and how that knowledge effects our own compost operation:

Most pesticides used on lawns and trees decompose in the composting process. This is partially a product of the heat, but more significantly occurs through the activity of the microbiological action. What these materials break down into is still unknown. That being said, all organic certification organizations recognize composting of these materials as an allowable function.

A certain lawn herbicide called clopyralid, used to control broad-leaf weeds, has been shown to be resistant to breakdown through composting. This fact was discovered in Washington State. Since then, other states have discovered the same problem. Clopyralid is generally not an issue in field situations, since the amount in any one spot is very small. It does become an issue in flower pots, containers or greenhouse operations. For that reason, we here at The Rodale Institute never use any compost that contains any grass ingredients in our greenhouse operations. Any compost containing grass clippings is used for field crops only.

I always recommend that interested individuals contact their own state Extension specialist in composting, since they have the best regional information. Then, on a national level, I suggest the journal Biocycle, at JG Press, Inc., in Emmaus, Pa., as the leading authority on compost.

Good Luck,


Have some questions to Ask Jeff? E-mail him directly at