manure test, how long do you think it will take?

why not use fast growing plants in pots of compost, then make a liquid manure feed (put some manure in a jar of water and give it a really good shake - if you want, leave it standing a day or two) then water the plants using that.  I would have thought results should be within a week or two - really good growth if okay, static to poorly growth if bad.

I started off my experiment about 2 weeks ago, the broad beans are just showing in the compost pots and today i noticed that the broad bean seeds in the half manure half compost pots are black and not doing anything.

Do people think that this could be to do with the fact that actually the manure isn't rotten enough (hence maybe not aminopyralid  ) as I believe it could have potentially just been scraped straight out of the barn right before when i went to collect it? is this a trademark sign as to what happens to the seeds in this case?

how long do people usually leave manure to rot properly?

thanks in advance

Thanks yorkie. It was probably around 6 weeks old when it went on the soil and is now probably around 4 months old so hopefully that is the problem!!!