Slate ; I fertilizer the big live oaks around my stands each year.I put about 10lbs. to the big trees,I put it around the edge(drip line) of the limbs and some under the tree.
I have been useing 10-10-10 for several years.it seems to work fine.
I will do it just after the deer season ends,that is befor the trees put on the blooms.

it has helped me have acorns when there are none on the other trees.

if you have any persimmons around,put some under and around them also.the deer love them better than acorns.