In tree crops fertiliser is not added near the trunk because of

In tree crops, fertilizer is not added near the trunk because of fewer roots there.
Roots are the part of the plant that absorbs water and mixed solutes and fertilizers from the soil. As the trunk presence of the root is very less, therefore it is advised not to add fertilizers near to trunk of the tree.
For trees growing on turf, fertilizer is best applied beneath the root zone of the grass. Punch, drill, or dig small holes 8 - 12" deep evenly spaced around the dripline (about 3 feet apart) and distribute the fertilizer equally among the holes.