Yeah, they do that here too, or so I've been told. I've never called them, but I should. You can go to their office and get some little boxes to put soil samples in, the instructions for where and how to take them are on the box, and you can send them off to the state lab for analysis. They'll send you back a detailed list of exactly what kinds of fertilizers and in what proportions you need to put on your pastures. I think it may actually be the Soil Conservation office that you need to talk to instead of the Extension Service.
I'm not even sure we have one of those! I'll look.