Lloyd

You know what heats up a compost pile really well? Coffee chaff. Just put a garbage bag full in my cubic yard of fall leaves that had been sitting there all winter, within days it was steaming and it has noticeably shrunk. We got a lot of rain this weekend so I have to go turn it (even though it was mostly covered), will let you know how the inside was. I have to get a compost thermometer - my automotive A/C thermometer I use for soil testing is too short.

The process is called mineralization. Usually it is measured at the site of application; if it is applied to a lawn, the persistence of the chemical is measured in the soil where it was applied. The process of breaking down the chemicals is typically via bacteria, so the presence of organic material that is decomposing affects the rate of decomposition of the chemical.

Composting will, of course, speed the breakdown of these sorts of chemicals. My compost takes about two years to complete.

So it becomes a judgement call. If you are comfortable knowing that lawn chemicals are designed to break down via bacteria, then you might be ok with other people's grass clippings if you compost it for a couple of years.

Obviously, if you use lawn chemicals on your own lawn, you will know when they were last applied. You might want to dispose of the grass clippings right after a chemical application.