However, pulling them out of the mulch will be much easier. Areas of heavy rainfall may increase the chance of soil diseases. Mulches need to be kept clear of the bud union, otherwise rooting from the scion may take place. As the mulch decays, nitrogen will be released. In fact, it may be more than is needed at the time.
Roots tend to grow near the surface.
If more mulch isn't added each year, the roots may experience damage from freezing. This experiment may yield data on each mulch's effectiveness in weed control, tree growth, nitrogen content in leaves, and fruit quality. Each fall a cross-section of the tree stems are measured for tree growth. Leaves are picked and analyzed for nitrogen content. Apples are tested and measured for starch and sugar content and size.