grass clippings with weed killer ??

just wondering about using grass that has been fertilized and had weed killer applied ,i do mulch my lawn all the time and its been about
3 months since the weed killer has been applied,was wanting to use the fall grass in my compose tumbler,will this hurt anything?

I would think that it depeneds on WHICH weed killers were in the mix. But it wouldn't help if you know: I don't know which ones are persistent and which (allegedly) break down quickly.

I know there are many where the vendor claims it disapears soon after hitting soil, that you have to get it on leaves to kill a weed. And that might even be true, but I would believe it quicker if someone other than the vendors rated them!

I do think that sun, oxygen and microbes can digest almost anything, but the few things they can't digest are just the sorts of things that chemists know how to make.

I usually don't worry, but once I used the sand from under an above-ground swimming pool to amend lawn soil. I think it must have had a lot of persistent SOMEthing, because those amended spots were worse than ever for a few years, then started to come back.

If you have time and energy for experimentation, keep the suspect clippings in a small heap of their own., Keep trying to grow something very sensitive right on top of the compost heap (peas??) If they won't sprout, keep composting those clippings until until new seeds can sprout.

yea i think i will pass on using the grass and use horse manure instead,i have an endless supply of card board do i have to shred it ?what size should it be? ,i do shred my paper .

I think the main reason to shred paper or cardboard is to reduce the tendency to matt down and exclude air.
The seocnd reason is that small pieces will get "eaten" faster. But since it is thin, it opught to get eaten pretty quickly anyway, especially with plenty of high-N manure around it.

I would think that pieces as big as your hand ought to be OK. Say 6" on a side. But the main consideration is that air has to be able to get in.

If you turn it often (for example in a tumbler) or it's a small heap, or twigs or something keep it fluffed up, then matting down shyould not be a big problem.

Soaking cardbolard ofr a day or two ought to make it fall apart easily. Otherwise, it will be a lot of work.