Establishment and productivity of irrigated switchgrass across ecozones in California.

摘要

Bioethanol has been produced from maize grains in the US. Several negative aspects of maize based bioethanol have been reported, such as low ethanol productivity and net energy production (Pimentel 1996, 2001; Pimentel and Patzek 2005) and high greenhouse gas emissions (Adler et al. 2007). However, technology is being developed to produce ethanol from cellulose, proposed to offer energy and environmental and economic advantages over current biofuel sources (Schmer et al. 2008).;Cellulosic ethanol can be produced from urban and agricultural wastes, such as rice and wheat straw, wood chips from tree pruning and dedicated energy crops. High biomass yielding crops, like switchgrass (Panicum virgatum ), are candidates to be used solely as cellulosic energy crops. Switchgrass has been promoted as a biofuel crop because of its high yield potential, relatively low fertilizer requirement, soil conservation attributes and compatibility with conventional farming practices (McLaughlin 1992).;Switchgrass is a C4 warm-season perennial grass native to the North American Prairies. It has been grown in the US as a forage crop, for grazing and for ground cover. Only recently it has received attention as a promising cellulosic biofuel crop. Most research on switchgrass has been conducted in the Midwest and Southern US under rain-fed conditions and little is known about the adaptability and productivity of switchgrass in California. Basic information, such as establishment methods, weed control options and optimal fertilization under irrigated condition remains lacking. In addition, California is composed of different ecozones, ranging from high elevation intermountain regions, to Mediterranean climates and true deserts, where switchgrass adaptability and yield response to nitrogen will differ.