ABSTRACT This study was carried out to develop and evaluate a coal ash production of developed carbonizer from rice straw to overcome its burning, decrease CO₂ emission and decrease the time for producing coal ash as a soil conditioner. The effect of rice straw (chopped and un-chopped), at moisture content (10.03, 12.13 and 15.20% (w.b.), air velocity (0.5, 1.0, 1.5 and 2.0 m/s) and rice straw weight (10, 20, 30 and 40 kg) on carbonizer productivity. Also, study the effect of operating parameters such as burning time, burning rate, air flow and carbon dioxide emission. The results showed that, the optimum operating conditions of the developed carbonizer was at raw materials moisture content of 10.03% (w.b.) and air velocity of 2 m/s. Where, it gave carbonizer productivity of 2.79 and 2.37 kg/h, for chopped and un-chopped rice straw, respectively. Moreover, the optimum operating conditions gave the best results as well as burning time of  5.58 and 7.68 min, burning rate of about 4.66 and 4.22 kg/min, air flow of 0.71 and 0.62 m³/min and carbon dioxide emission of 5.56 and 7.03 for chopped and un-chopped rice straw, respectively. It was clear from the results that the use of carbonizer with the development of an air flow system leads to a reduction in carbon dioxide emissions, increasing in disposal of rice straw and obtaining a good soil conditioner.