Hello Larry,
I use a broadfork to loosen the soil deeper than I can with a spading fork. If a spading fork works deep enough to satisfy you, then you have no need for a broad fork.
In order to explore your soil situation, take a spade or post-hole digger and dig down as deep as your curiosity takes you. My Merry Tiller will till no deeper than about 8 inches for "regular" tilling in which I let the tiller keep moving forward at a reasonable pace. If I hold down on the drag stake, it can dig down maybe 12 inches. Tilling 12 inches deep is slow, as is manually spade-forking to 12 inches.
We seem to have a hardpan at about the 12 to 14 inch depth. I can "tickle" that hardpan with a broadfork, but that is slow exercise. A few years ago I saw a broadfork for sale that could penetrate to 24 inches or more, but for me that would be a frustrating encounter with hardpan and, in some places, tree roots. And I doubt that I am strong enough to use such a broadfork effectively. I actually have a couple of broadforks, but I get one of them out only when I want to get some strenuous exercise.
ZM
