Another question -horse manure and miscanthus

[Rose willow]

So sorry but I have another question. I will try not to ask any for a while now

i have been offered some horse manure with miscanthus straw. I had no idea what this was so googled it and it’s a type of grass. I am presuming if I leave it in a pile to rot down this would be ok to use?

[burnie]

Have a read of this, it's not what straw is in it, but what has been added
Aminopyralid contaminated manure - Information on removal, finding safe manure - The Grapevine (growfruitandveg.co.uk)

[Rose willow]

I wasn’t aware of that. Just read the article and googled a bit more and it seems that it’s even now in compost you can buy from shops. I think I either won’t get any horse manure or get it and leave it for a year. Thanks

[ameno]

Contaminated manure is easy enough to test for, so I wouldn't dismiss it just yet.
First of all, ask the supplier if they use any weedkillers on their pasture.
Assuming they answer "no", just get a small amount to start with, and test it with broad bean or pea seeds (sow some seed in the well-rotted manure, and some in your usual compost, then compare the seedlings once they come up. If the manure is contaminated, the leaves will grow twisted, distorted or cupped). If it passes the test, go get some more.