A few years ago i had a muck heap in the field i was renting. We used to burn it about twice a year. Ended up with a letter from the council as someone had complained about the smell. The letter did not say i was doing anything illegal but i was to be more considerate when doing it wind directions etc. Got my own back though as they used to frequently (every month) burn garden rubbish from a very large garden which makes a massive amount of smoke, it completely covered the road and was dangerous so i reported them!!!