Hydrolysis experiments of the nitrided fly ash were carried out in dilute aqueous suspensions. An ammonium electrode and a pH electrode were used to measure the extent of the hydrolysis. For comparison purposes, hydrolysis studies were also performed for the commercially available nitrides. At the initial stage of the hydrolysis, a linear relationship exists between the hydroxide concentration and the hydrolysis time. Accordingly, a slope can be extracted from this linear relationship. A comparison of the slopes could be an effective method to evaluate the extent of the hydrolysis of nitride particles. A novel application of the nitrided fly ash is revealed in this paper. The ammonia released slowly from the hydrolysis of the nitrided fly ash has the potential to be a very good nitrogen fertilizer. Certain salts can slow the hydrolysis of the nitrided fly ash, as for example calcium carbonate, and a slow ammonia release can be achieved.