definately let it season over winter. I have a neighbor that has horses and i put it on in early sping and tilled it in well with the rest of the soil. I had tomatoe plants around 6' tall and so many that fruit was rotting on the vine. The peppers seem to be very happy as well. Weed control is first and formost. I left open ground spots between the rows and now find that was a mistake, weeds will certainly take over if left for any amount of time.A horse's digestive system isn't as thorough as other herbivores, so quite a bit of their grain passes whole through their g.i. tract. If you till in the fresh stuff in the fall and let it mellow over the winter, mulch well to keep down weeds when you plant out.
Thanks for the feedback guys. The manuare has been dumped on a composter at the farm and is probably 4-6 months old now. Am looking to add it into the sils before planting.
Horses were fed only on pellets and lucerne and never grazed in fields... so I am hoping weekds should be fairy ok?
So I just mix it up good with the top soil?