Thanks for the feedbacks. I don't have a soil analysis, but my understanding is that the issue with pecans isn't so much a zinc deficiency in the soil as it is a very strong demand for zinc during nut production.
There are a lot of unknown variables here. Pecan trees do have deep tap roots for
water, but the vast majority of their
root system is quite shallow. Thus I do believe there's hope that a zinc-accumulating dynamic accumulator has the potential to be of assistance, by bringing up zinc from deep soils that aren't near the tree's tap root or any other part of its root system. Unfortunately I haven't identified a likely dynamic accumulator plant for this purpose yet.
I am interested to hear that red cedars are zinc accumulators. I'm not growing them under my pecan trees, but I have a lot of them growing elsewhere on the property and they often are crowding trees I like better. I wonder if it would be worth mulching them under my pecan trees?
Even if my pecan trees have consumed all the available zinc near them, I continue to hope I could grow zinc accumulators elsewhere and bring in the foilage as mulch. I just don't know how practical that is, or whether the necessary volumes are too large.
Thanks, John Elliot, for the tip about batteries. However it does seem to me not a big step from just breaking down and applying zinc sulphate from the
feed store.