BioEnergy Research

Efficient conversion of lignocellulosic feedstocks to ethanol will benefit from a consistent composition of supplied biomass. While composition or quality for a given feedstock is known to vary, the influence of environment, rather than genotype, has rarely been separated for mature field-grown material. Replicated trials of a single sterile hybrid clone of Miscanthus x giganteus across Illinois provided a unique opportunity to test the influence of environmental, rather than genetic control over biomass composition, under US Midwest conditions. Given the interest in M. x giganteus cv. Illinois as a lignocellulosic feedstock, it is valuable to understand the variation in composition of this crop that would need to be dealt with by processors. This study examined the effect of seven sites spanning nearly 5° in latitude and contrasting soil types from sands to clays with land capability classes ranging from 1 to 4. Four levels of nitrogen fertilization (0, 67, 135, and 202 kg N h^-1) were applied on these mature, genetically identical, clonally propagated stands of M. x giganteus which were harvested both pre- and post-senescence. Despite the wide range of environmental differences, there was minimal variation in the composition across all locations, sampling times, and fertilization treatments. Composition varied from 39-45 % for cellulose, 19–24 % for hemicellulose, to 19-24 % for lignin. Nitrogen fertilization, while having a small effect, decreased the proportion of hemicellulose, acetyl groups, and ash and increased cellulose and lignin at statistically significant levels. Delaying harvest from October to December increased the proportion of cellulose, hemicellulose, and lignin and decreased the proportion of ash and extractables at statistically significant levels. The findings show that in the absence of genetic variation, composition varies minimally with environment or timing of harvest, which has important implications for costs of processing in a given location.