Preliminary study of fuelwood properties in a short-rotation tree, Indigofera tinctoria planted in Indonesia

Indigofera tinctoria L. is known to produce economically valuable indigo dye. Recently, I. tinctoria has also been considered a potential species for establishing energy plantations because this species can rapidly produce large quantities of biomass. However, knowledge about its fuelwood properties is still limited. To optimize utilization of this biomass material as a source of energy, the fuelwood properties of this species were evaluated. In addition, the effect of radial growth rate on fuelwood properties in this species by mixed-effect modeling approaches were also evaluated. The productivity rate of above-ground biomass was found to be 7.4 tons ha-1 year -1. The estimated average values in fresh weight, dry weight, moisture content, ash content, and carbon content were 7.4 kg, 3.7 kg, 53.4%, 0.90%, and 1.6 kg, respectively. According to the results of mixed-effect modeling, it is concluded that faster-growth characteristics of the tree did not always deteriorate the fuelwood properties of this species.