Originally Posted by CL&T
I've used a pruning blade like that and they are good but not in soil. They'll dull in short order like any other wood blade. That's why I mentioned that carbide tipped Sawzall blade.
You're right of course, and I have used those carbide tipped sawzall blades (Freud Demo Demon) with great success on other projects (I liked them so much, I cut out a piece and welded it to a blade shank, so I can use one with my Fein tool).
But they're not really appropriate for green wood. Look at how open the tooth space is on that pruning blade. You need that to remove the fibers from cutting live wood (a chainsaw gets around chip removal in a better way, but that's not really a good idea in dirt).
What you need (but does not exist), is a carbide tipped pruning blade. Something with carbide teeth, but a tooth design made for green wood, not dried construction materials. If I really needed to do this a lot, I'd probably modify some of these by removing every other tooth.