Biological conversion of biomass (energy crops, agricultural wastes) and various organic wastes is
regarded as a sustainable production of renewable energy in future. Biogas is a versatile renewable energy
source,which can be used for production of vehicle fuel,electric power and heat, chemicals and materials
[1,2,3]. Meanwhile, the production of biogas can drastically reduce greenhouse gases (GHG) emissions
compared to fossil fuels. Another by-product of biogas production named as digestate is an improved
fertilizer in term of its availability to crops which can substitute mineral fertilizer and reduce the nitrogen
leaching from arable land to cycle the nutrient in the ecosystem[3]. It was reported that there are extremely rich bio-natural gas resources in China and its annual productivity is expected to over 150 billion m3.
Distributed energy development is initiative in China[4]. Therefore, it is more important to grow more
plants in the marginal lands for both bio-energy production and ecological management.
Vetiver (Vetiveria zizanioides) is a perennial tufted grass belonging to the Poaceae family and the
common domesticated cultivars used around the world are non-invasive. It has become known as a
miracle grass with diverse environmental applications, including:a source of scented oil from its roots,
fodder for livestock, soil and water conservation, rehabilitation, and remediation,and waste water
treatment. It also sequesters significant quantities of atmospheric carbon[5]. However, there is little
information of vetiver plant as raw material of bio-energy. In this study, the experiment was carried out to
compare the effect of harvest time on the biogas productivity in order to develop a new ecological
industry of vetiver plants from the perspective of ecology and energy.