Used to be, a man could meander into the town hardware store (I think Hinkles (sp?) Hardware in Clarksburg, Ontario) and grab a box of explosives for such tasks.  We once (in the 80s) bought a box of forcite 40% for a weekend of fun!  Surprised us, how much you actually needed for underground work.
		
		
	 
...that might be what you call a twofer (i.e. 2-4-1),  you can get rid of the barn too!
A root ball can weigh a LOT.  I don't think it takes a very big root ball to equal a cubic yard of dirt (which can be over a ton) 
"Give me a lever long enough and a fulcrum on which to place it, and I shall move the world."- Archimedes (paraphrase).  
It's surprising what a cable attached 12' (or 16' 20') up the tree can do when your levering out a 3' deep root ball.  
I found these numbers on the web (must be true!), but actually the weights seem a little light.  These were planting guidelines, not removal, so take them with a grain of salt. 
Tree diameter   Root Ball Diameter    Estimated Weight
1.0 - 1.5"              19"                       150 lbs.
1.5 - 2.0"              24"                       300 lbs.
2.0 - 2.5"              26"                       400 lbs.
2.5 - 3.0"              28"                       550 lbs.
3.0 - 3.5"              35"                       900 lbs.
3.5 - 4.0"              40"                       1,500 lbs.
4.0 - 4.5"              45"                       2,200 lbs.
4.5 - 5.0"              51"                       3,200 lbs.
5.0 - 6.0"              57"                       4,600 lbs.
6.0 - 7.0"              65"                       5,500 lbs.