Interestingly, walnuts can be pollarded.
I want edible perennials in the mix, and the book describes a rotational pollarding system to ensure the annuals get enough light. This might not be optimal for walnut harvesting though. Does anyone know how much harvest to expect from pollarded walnut trees over a nine year cycle?
I tend to prefer the edible perennials over annuals longer term as the harvest is higher and significantly less work. Maybe just planting the trees 20m apart will enable centre rows of annuals to get decent sun even when they're mature. Although that would decrease annual rotation options. Ideas anyone?