Horse manure
By Googie
cheshire,
United Kingdom 
I put some year old horse manure on my garden at the start of this year. My garden has been full of bits grass and has been a real struggle to keep it down, I have never had this before, have had the weeds but never this much weed grass gowing. Could this be the horse manure I put down, in the past I have used the ready bagged stuff you get from B& Q.
10 Jul, 2009
I should think that is the most likely explanation - and I was always instructed that horse manure should have been composted for 2 years before applying to the soil. Given that its composted mixed with straw, then its quite likely that the straw had grass seeds in it.
10 Jul, 2009