The low fertility of soils of the eastern plains of Colombia makes it necessary to search for methods of improving different soil properties. Fertile soils increase yields of different crops in the region, and particularly agroforestry agroecosystems will increase wood volume. Including stabilized waste residues such as biochar will probably increase fertility. The objective of this research was to estimate the optimal volume of Acacia mangiumwood that can be obtained, when using two fertilizers applied to the soil at two levels, fitting a central composite design with star points. In the model, two levels of treatment were applied: 40 and 80 ton · ha-1of biochar and 50 and 100 g per plant ofsynthetic fertilizer 15-15-15. The optimum wood volume was found at 8566.9 cm3when the biochar was combined with 63.1 ton·ha-1and 15-15-15 at a dose of 84.4 g per plant.