[ampsucker]

i would think a good slip clutch adjusted properly on a tiller would eliminate any problems with hitting the occasional stump or root.

my question is what do you hope to grow in a bed of red pine mulch? you'll need to lime the heck out of it and add a ton of nitrogen and even then you'll probably need to let it sit for several years before you get good growth. of course, blueberries do like the low pH!

tilling it under WILL help it decompose faster, but you're still creating a huge nitrogen sink with all that carbon decomposing.

you might also consider a mold board plow to turn the top over before tilling. that will help you a lot with getting it mixed up.

amp