I'm a landscaper and so I've always got tons grass clippings to get rid of. I'd say half of the yards I mow are treated (mistreated) by companies like trugreen, Turf masters, top Turf, and etc. I don't know what all they're treated with. Sometimes they spray and sometimes it's pellets. Every company just about does 7 treatments per year per yard. I'd imagine at least half of those treatments are fertilizer, and one or two treatments of pre and post emergent herbicides. Currently I pay money to dispose of at dump. But how long do you suppose they'd have to compost for to be chemical free? Think it'd be safe compost to use in food forest after a year or two?