"David Hill" wrote in message
...
I don't know what horses in the US are feed, but we always recon that Horse
manure is cleaner than most manures as Horses tend not to eat seed heads,
and the hay fed to them is of better quality than that feed to Cattle so has
little or no weed seed in it. Also the straw used is also almost weed free,
and if they are bedded on shavings or saw dust then that is weed free.
Mushrooms are chiefly grown on Stable (horse) manure which is very rich in
straw, and the resulting compost is just about 100% weed free.
Could the weeds be because the soil fertility is improved from the manuring?

Not here in the SE USA. Horses are fed hay that contains a large variety of
seed, all the way from morning glory to wheat and rye, cockleburs and
sandspurs. Like I said, for me, it has to be well aged to the point it's
black and crumbles in the hand. In other words, it has to be fully composted
when I pick it up at the stable, and they have plenty!!

Tom J