You can grow in the bales themselves. I have done it before, and it worked just fine. It is the cat's meow for growing taters. Only trade off is they need more watering.

Thanks centexan.
I've tried growing in them, and it just doesn't work for me. But my plan is to use this stocktank I bought, and was wanting to lift it up on bales.
But I remembered that farmers stack these bales up to the ceilings in their barns and they don't collapse........so I think I'm okay for this summer.
Plus.....I've been reading about straw bale houses!