I added some sand in my potatoe patch. But I have to keep planting in the same spot. They loved the sandy soil and it sure was easier to dig. Cant help you on the fertilizer. I use a 8-32-16 on everything in the garden.

You want some compost or manure in there, well-rotted. They don't need fertilizer unless you are correcting a deficiency. The bed gets manure in the fall then planted out in April and no problem with yields.

And definitely don't plant them in the same place every year or give everything the same formulation.

Dan

One of my favorite gardening books (can't remember the name) suggests mixing in sawdust in the potato patch to absorb excess nitrogen but leaving the other nutrients alone. Plus it makes a nice sifty dirt the potatoes love. Makes kind of sense, I'm trying it this year.