Certified GKH Gardening Expert
Most trees do not need supplemental fertilizer, but it sounds like you have some concerns about your tree. Are you seeing health problems with the tree? If so, let us know the symptoms and we can help identify what is wrong with the tree. In general, if you are going to fertilize a tree, a fertilizer with a high N, a low or no P and a moderate K is best for non-fruiting trees (such as 30-0-10 or 32-3-10). If you are looking to get nuts from the tree, then you would use a fertilizer that has a moderate P (such as 30-10-10).