BIOMASS PRODUCTION AND BIOCHEMICAL METHANE POTENTIAL OF SEASONALLY FLOODED INTER-GENERIC AND INTER-SPECIFIC SACCHARUM HYBRIDS

Production of biomass crops for energy can compete with food crop production for quality, arable land. Certain biomass crops may be well suited to marginal sites which do not favor food crop production. This study was conducted to evaluate biomass production on a wetland site which, without extensive and costly conversion, would be unsuitable for conventional agricultural production. Nine clones of the Saccharum taxonomic complex were evaluated for biomass production and methane conversion after being flooded for six months in each of two crop years. Erianthus arundinaceus clones were intolerant of flood and subsequently were low in biomass production. Inter-specific and inter-generic hybrids of commercial sugarcane with E. arundinaceus and S. spontaneum produced well under flood. All clones were more productive in ratoon (regrowth crop). Rates of methane conversion under mesophilic conditions (35-degrees-C) ranged from 0.060 to 0.095 day-1 and methane yield was from 0.266 to 0.314 liter g-1 volatile solids (VS). Biomass dry matter yield varied widely from 0.47 to 20.28 Mg ha-1 in the plant-crop and 4.57 to 60.1 Mg ha-1 in ratoon. Using the mean sample value observed for methane yield, this corresponds to upper methane yields of 5.89 and 17.4 x 10(6) liter ha-1 year-1 for the plant and ratoon crops, respectively. The wide crosses appear to have good potential for biomass production in areas prone to periodic flooding.