Requiem for a Potato Bed

Today I went out and dug out all my potatoes.  I'm so depressed.  It was without a doubt the best crop I've ever had.  It was heartbreaking digging out so many beautiful potatoes and dumping them in the green waste bin.  A couple of times I cut one, thinking maybe I'd find a good one, but no.  This is what they all looked like, some even worse.

I got four and a half buckets full, totaling 150 pounds.  I know, because I weighed one.

Well, now I know the secret of getting a big potato crop.  Actually two secrets, from Eliot Coleman and Barbara Damrosch.  Dig a trench as usual, but plant the potatoes even deeper using a bulb planter.  And give them lots of water.  Someday I may try them again, but not in this garden. 

Update:  After turning the problem over to Neil to research, I've learned that the problem is lack of calcium.  Maybe this one variety (German Butterball) needs more.  So I will try again.