Most farmers --- and I'm no exception --- get tunnel vision about producing the crops they're interested in.  But permaculture admonishes us to put in some species which have other uses beyond going in our bellies.  I don't spend too much time worrying about planting nectaries since the majority of our property is one huge nectary and our "lawn" is primarily flowering weeds.  On the other hand, I'm now starting to think seriously about dynamic accumulators.

Dynamic accumulators are plants which are good at mining nutrients out of the soil...