Bullshit would be a good soil amendment. I'm afraid these have to make do in mostly clay, with compost mixed in from my compost pile.
I think it had more to do with getting rain in patches last year, instead of on a more regular basis. I mostly didn't water, either, leaving them struggling on their own.
I don't seem to have been the only one--other gardens, and even the walnut crop, failed too.
Cheers, James Arthur