The synthesis results are influenced by fly ash characteristics and different synthesis conditions (KOHsolution concentrations, activation temperature, time, and KOH/fly ash ratios). A high quality merlinoite-rich product was synthesized under optimal activation conditions (KOH concentration of 5 M, activationtemperature of 150◦C, activation time of 8 h and KOH/fly ash ratio of 2 l/kg), with a cation exchange capac-ity (CEC) of 160 cmol kg−1. The synthetic merlinoite is proved to be an efficient slow release K-fertilizerfor plant growth, indicating that it can be widely used for high-nutrient demanding crops growing innutrient-limited soils and for large-area poor soil amendment in opencast coal mine areas around thepower plants that will substantially grow with the increasing coal combustion in Xinjiang in the nearfuture