Hi, as I have said in previous replies please be very careful of where you get your horse manure some horse owners sprayed their fields and meadows with a weed killer called Forfront there are many different trade names to this chemical but if is present in the horse muck it can take up to 3 years and maybe more for it to break down , it causes potato Hume's to curl like the fonds on bracken and the leaves of bean peas to wilt .
Derek