Vol. 16 No. 1
Second generation biofuel crops from poor quality water and degraded lands
Abstract: Poor quality water and lands are in ample supply in Australia. Ongoing drought in many regions has renewed and increased interest in uses of saline wastewater rather than disposal to evaporation basins. This paper reports on use of wastewater and saline land to grow a new second generation biofuel crop, Arundo donax (L.). Arundo donax, commonly known as giant reed, is a perennial, rhizomatous grass that has been grown in every state of Australia for over 150 years and in many other countries. Together with other cellulose feedstocks giant reed could form the basis of a new biofuel or pulp/paper industry for Australia and other countries. This paper reports two field studies from South Australia where high biomass yields (45-51 dry t ha-1year-1) of A. donax was achieved on degraded, saline soils using domestic and winery wastewater. Irrigated A. donax yields year-1 exceeded any alternative crop reported for warm to sub-tropical climates. The calorific value of 19 MJ kg-1 of dry A. donax is equivalent to about 75per cent of that obtained from a kg of coal. Within the first year of growth with saline winery wastewater, Arundo removed 528 kg N, 22 kg P, and 664 kg K respectively, in each hectare of harvested biomass while tolerating 5-10 dS/m soil water salinity for several months when the topsoil was kept near field capacity. We classed A. donax a halophyte. Successful growth and containment of A. donax spread requires careful management. Arundo donax can invade riparian systems and is declared noxious in many parts of Australia. However, due to polyploidy A. donax does not produce viable seed, this together with its clumping rhizome growth habit means that its ability to spread is limited when plantings are managed carefully, and crops are planted in non-riparian systems and not planted in riparian systems subject to flooding as described in this paper.
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