Bioenergy Feedstock Production on Saline Soils Using Marginal Quality Water in Arid Climate.

In the recent years, interest in biobased fuels is increasing and the mandated goal by the US congress is to use at least 137 billion liters of bio-based transportation fuels by 2022. Meeting this stated goal requires a comprehensive regional strategy that includes bringing additional areas from different regions within the country under the bioenergy crops. While the southwest U.S. has adequate supply of land, finding reliable source of water to produce bioenergy crops is the main challenge. This challenge can be met by developing marginal quality water sources for bioenergy crops production. Information on bioenergy crops performance under elevated salinity is not well documented. This study evaluated switchgrass (Panicum virgatum L.) performance under urban wastewater irrigation using columns prepared from a salt affected land over four years under greenhouse conditions. Results indicated that among the cultivars evaluated, a lowland ecotype "Alamo" was the most salt tolerant. Switchgrass biomass production stabilized after the initial high response to irrigation. Four years average biomass yields ranged from 16 to 20 Mg for different treatments evaluated in the study. Qualities of biomass under treated urban wastewater were comparable to that produced under freshwater irrigation. Estimated ethanol yields ranged from 5280 to 6624 liters per hectare. Soil salinity increased with time under both freshwater and wastewater irrigation, however, sodicity of the soils remained below threshold level. This indicated that most of the salinity increase was due to solubilization of calcium salts, which is less problematic than that produced by sodium salts.