Biomass Production of Several Warm and Cool Season Grasses Under Varying Irrigation Amounts in Western Nevada.

Interest in the production of cellulosic biomass as a source of ethanol has increased dramatically in response to questions concerning the sustainability of starch based ethanol sources and federal mandates that required the production of up to 16 billion gallons of cellulosic ethanol annually by 2022. While warm season grasses have been the focus of most research efforts, relatively little research has been completed concerning the production potential of warm season grasses for biomass under irrigation in the West. The purpose of this work was to examine the production potentials of four cool season and five warm season grasses under varying amounts of applied irrigation in western Nevada. Studies were completed at two locations in Lyon County, Nevada from 2008 through 2011. Three water treatments were applied to all grasses annually and represented roughly 50, 75, and 100 percent of normal irrigation water applications in this area. Data collection included biomass production, weed resistance, rooting depth, and root architecture.  The grasses were harvested once per season when dormant. Biomass production generally increased with increasing water applications.  Average warm season grass production values exceeded the cool season species after two growing seasons in the highest water application treatments. The cool season species were generally more productive than the warm season grasses at the lowest water application rates and were more weed resistant. Root depth was not correlated with biomass production. Abundance of fine roots was however correlated with increased biomass and fewer weeds. Bluestem (Bothrichloa ischaemum) was the top producing warm season grass, while tall wheatgrass (Elytrigia elongata) was the highest producing cool season species.  Neither grass type produced adequate amounts of biomass to successfully compete with alfalfa as a revenue producing crop.