My opinion only. Takes extra time but I can burn anything I cut down without letting it dry forever. Have even burnt green stuff with leaves on it and the hot coals boil the sap right out if it.

You need to build a hot base fire and get a good bed of coals then feed stuff into it. If you do it this way you can burn anything green or not stumps whatever.

Nobody likes this way because it takes extra time and effort.

Too many people want to take a big pile and use lots of fuel or tires to try and start it in place.  Usually burn the fines out quickly and your left with big things that won't burn very well because you have no base fire providing intense lasting heat. Also makes lots of smoke and brings lots of "attention"

The hot bed of coals does the work for you. You have to build them first. They provide the heat to dry the stuff enough to make it burn. 

I usually cut and put stuff in smaller piles more spread out. Get a good hot fire going about somewhere in the middle of all the piles with dry seasoned wood then start feeding in the piles. 3 point blade reversed on a tractor with frozen ground is ideal to move piles to the fire.

Some will say it's risky pushing piles into a fire in case the machine quits but I've found I never need to get that close to the fire. With the pile behind the reversed blade the heat is so intense that even close to the fire the stuff starts burning. It would get to the point it would burn stuff about as fast as you could push piles into it.

Like I said my experience only, others mileage may vary. Can it be done the other way ? yes. My way only requires some dry wood, and a few paper bags and some patience not gallons of fuel or oil and tires. Some bigger fires I could come back a week later and dig in the ashes and still find red hot coals. If you keep coming back pushing stubs and stuff in when your all done there will be nothing left not stumps or anything but ashes.