To optimize the biochar and nitrogen fertilizer, an experiment was conducted based on CCD. The high and low levels of biochar were 0 and 40 t.ha1 and 0 and 300 kg.ha1 of nitrogen fertilizer, respectively. Grain yield, nitrogen losses, and NUE were measured as the dependent variables. The optimal amount of biochar and nitrogen fertilizer was calculated based on three economic, environmental, and economic-environmental scenarios. In site 1, the highest grain yield was obtained at 40 t.ha1 of biochar and 300 kg.ha1 of the nitrogen fertilizer. In site 2, it was obtained at 20 t.ha1 of biochar and 300 kg.ha1 of the nitrogen fertilizer. The lowest nitrogen losses were obtained in 40 t.ha1 of biochar and 0 kg.ha1 of the nitrogen fertilizer in the two sites. In both sites, the highest NUE was obtained in 20 t.ha1 of biochar and 150 kg.ha1 of the nitrogen fertilizer. In site 1, the optimum amount of independent variables in the economic scenario was 29.49 t.ha1 of biochar and 239.39 kg.ha1 of the nitrogen fertilizer. In the environmental scenario, the optimum amount of biochar and nitrogen fertilizer equaled 40 t.ha1 and 55 kg.ha1, respectively. The optimum amount of these in the economic-environmental scenarios was 20 t.ha1 of biochar and 97 kg.ha1 of the nitrogen fertilizer. In site 2, the optimum amount of biochar and nitrogen fertilizer in economic, environmental, and economicenvironmental scenarios equaled 23.8 t.ha1 of biochar and 263.6 kg.ha1 of the nitrogen fertilizer, 40 t.ha1 of biochar and 97 kg.ha1 of the nitrogen fertilizer, and 19.4 t.ha1 of biochar and 133.3 kg.ha1 of the nitrogen fertilizer, respectively.

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