Taken your advice, Peas

Peas, and other legumes are able to fix atmospheric nitrogen and store it in root nodules but they use most of it themselves. There is some left in the roots when the plant dies but it isn't available to other plants straight away.

Too much nitrogen on your taties will only encourage soft leafy growth, not the lovely spuds that you want. Potatoes are also heavy feeders which is why people tend to give them their own area and put peas in another. See various posts on crop rotation to see how this works.