This was just down road from me about 6 miles and I saw plenty of black smoke from the high winds fanning the flames. No cause has yet been determined, and luckily no workers injured. What the fire didn't get , smoke inhalation did....
bad deal, big loss. Disposal may not be as difficult as you think...high winds, lots of fat, lots of black smoke...perhaps pine strip will know more later
I would suspect electrical since the amonia from hog manure is very corrosive add methane gas to a small spark & this happens. I hope the farmer had enough insurance to somewhat recover from this loss.