I planted a 10X15 plot of sunchokes this spring, and only got out about 10 freezer bags worth. The stalks were blooming, plenty of ground cover from grass, but still fairly green, with a lot of woody parts. Why did my sunchokes not produce like John Kohler's/et al do?
While wild sunchokes may grow from a meadow, they don't produce like John Kohler's do either. For production, I'd keep the soil soft, and all other plants away. Lots of compost would help a lot. Deep, organic topsoil (the kind I wish I had) is what these will produce best in. It won't take near as much energy to push through.
You can fertilize them, with a general purpose fertilizer. Unlike many root crops, these (in my experience) get a boost with some nitrogen. Just don't overdo it or you'll end up with them lodging (falling over due to high winds or heavy rain).
Also, they do put on some at the end of the season. You can harvest them any time, but I like to wait until the tops die back in fall.