Fertilization - Although trees grow quite well in the forest without supplemental fertilization, urban and suburban soils may lack the vital nutrients that trees need. Many tree service companies offer fertilization as one of many plant health care practices.

One by-product of wood burning is wood ash, which in moderate amounts is a fertilizer (mainly potash), contributing minerals, but is strongly alkaline as it contains potassium hydroxide^[4] (lye). Wood ash can also be used to manufacture soap.