On saturday at the community garden I got to talking as I worked with a few people and mentioned my score of free horse manure. The others were interested and I got a call last night from one of them asking whether I might be interested in getting some more. In return for helping with the shovelling I got one trailerload which I piled up the front and she got a load which she is using to establish some garden beds. I've read a bit online about horse manure and it looks fairly useful, its supposed to have heaps of weed seed in when fresh and the nutrient content isnt particularly dense. The sawdust will take some nitrogen from the soil and the manure will supply some so as with most manures thorough composting is probably the best way of dealing with things.
Im concerned about antibiotics and worming medications in any farm manure but the fact that the pile was full of worms and had abundant weed growth on top allayed some of my fears. Its not ideal to be constantly bringing organic matter onto the site but if it allows for higher crops and improves the fertility of the system then things should be ok. My compost should be beautiful in a few months time anyway :)