Rather than dozing and piling the debris....
Perhaps you should have dozed it to take out the stumps.
Then followed it with a large hog/mulcher.
http://www.fecon.com/images/pdf/literature/products/2/Bull-Hog-(PTO)-50.pdf
Then you could have left the chips in place.
Of course, for grass, you might have been able to mulch the trees in place, without pushing them out with the dozer then broadcast planted the grass/forage, although you would have to repeatedly run the brush/flail mower over them for a few years to keep them down.
The problem with the piles is that it will be difficult to just run a hog over the piles, and you still won't get the benefit of the mulch in the fields.
With the piles, you'll likely choose to pull the piles apart and grind the debris. But, done right, you should be able to have saleable chips, perhaps even some paper quality chips.
As far as burning, I don't know the local rules and regulations. Certainly SMOG is a major issue around here. There may be some future changes, but most of the field burning has been stopped, and I think the government slash burning may be curtailed somewhat too. Rotting wood, of course, still produces CO[sub]2[/sub], although not as quickly as a fire. It should also add nutrients to the soil without scorching any of the clays.
