I have four peach trees that are four and five years old. Can I mulch and compost these trees right now what would you recommend I do it with?
Mulching can be helpful around young trees like yours to create a weed free zone around the tree. This helps protect the tree from mower and weed eater damage, and reduces the tree's need to compete with surrounding weeds for water and nutrients.
Also, a thick mulch can prevent "heaving" when repeated frost and thaw cycles can push young trees out of the ground. Unless there is already a heavy layer of mulch or compost around the base, it should be fine to add one. We don't want to add it in a volcano shape mounded up around the trunk, it should be a pretty evenly distributed layer with a small "bowl" or depression right around the trunk.