[Solitaire]

I have a huge pile of rotting hay in the horses field, it's where they have trod it into the mud and I have moved it out ot the way as they won't eat it.

Some of it isn't quiet rotted down, at that slimey stage, would it be all right to dig into the veg beds or should I leave it until it's better rotted down ??

[Yorkie]

I would wait until it's properly rotted.  If it decomposes in the soil, it will take nitrogen from the soil - which is then not available for plants at that time.

Just to check - the hay / grass wasn't treated with any form of herbicide, was it?  Otherwise you run the risk of the aminopyralid problem.

[RichardA]

I guess you know this but the mould that comes off hay is hazardous to human health though if in open air less of a  risk than in barns and stables but I would suggest you handle it when wet. In my opinion best to mix with other material in a compost heap so seeds etc rot down and use next year.
R

[Solitaire]

It probably was treated with something as they do spray over here, I'll leave it until next year when it's completely rotted down

[glallotments]

Soltaire,
If the hay was treated with certain herbicides leaving it for a year may not be good enough to ensure it is safe.

[woodburner]

Soltaire,
If the hay was treated with certain herbicides leaving it for a year may not be good enough to ensure it is safe.

Pyralid is broken dow n by SOIL living bacteria, so just because it's rotted down nicely is no guarantee whatsoever that the pyralid (if it has any) will be broken down.
The manure I got last year was lovely well rotted stuff, but still nearly killed my spuds!
That's not to say it's completely useless though. Once it's rotted down you can dig/fork it into the ground for the bacteria to break down the pyralid, and after a few months it will be safe even for plants to grow. If you can't wait til it's gone, you can grow alliums and sweet corn and other grains/grasses as they are unaffected by it, but they may take up the residue, so that any waste (stalks etc.) added to the compost heap may prolong the problem.