My Sweet Potatoes, Onions, Carrots And Other Root Vegetables Produce Very Little. Could There Be A Single Underlying Problem?

Question

I’m an experienced gardener and have taken all the steps I can think of to increase productivity, e.g. plant rotation, soil tests, watering. My plants look very healthy and produce plenty of vines, shoots and other vegetation above the ground. But the roots produce little or nothing.

Answer 1

Additional information about this question: Other vegetable plants, including tomatoes, peppers, beans, okra, Brussels sprouts etc. grow very productively in this garden,