PURPOSE: To obtain an effective fertilizer slowly producing its effect by positively ionizing the cellulose component of sawdust and ion-bonding a chemical fertilizer to the ionized cellulose component.

CONSTITUTION: Sawdust is soaked in a mixed aq. soln. prepd. by adding urea to sulfuric acid or phosphoric acid and the soaked sawdust is slightly squeezed and heat-treated to positively ionize the cellulose component. The sawdust is then dried, washed, dried and soaked in a soln. contg. the constituent elements of a chemical fertilizer such as copper and zinc and the soaked sawdust is dried to obtain sawdust having trace elements as a fertilizer. This fertilizer is prepd. in the form of natural fertilizer, slowly produces its effect after application and makes soil active and rich.