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
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.
Regional Food Bank of Oklahoma
Urban Harvest Marketing and Development VISTA
Here is what I know and how that knowledge effects our own compost
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
at JG Press, Inc., in Emmaus, Pa., as the leading authority on compost.
Have some questions to Ask Jeff? E-mail him
directly at email@example.com.