Water Use and Conservation Under Bioenergy Crops In the Central Great Plains.

Government mandates to increase renewable energy sources and concerns over groundwater depletion of the Ogallala aquifer warrant an assessment of water use and efficiency under dedicated energy crops in the central Great Plains.  The use of renewable feedstocks to produce cellulosic ethanol is quickly becoming a reality as facilities to produce cellulosic ethanol are scheduled to open in the USA in the upcoming years.  Crop residues particularly corn (Zea mays L.) stover will be the primary initial feedstock for these facilities.  However, dedicated energy crops such as perennial warm season grasses, if grown in marginal and degraded lands,  may be a more sustainable feedstock alternative for ethanol production due to their high potential biomass yield, deep-root system, rapid growth, low-maintenance, drought-tolerance, and high adaptability to marginal lands as compared to other common grass species.  The objective of this project was to assess the impacts of growing perennial warm season grasses on soil hydraulic properties as compared with row crops in dryland conditions.  Switchgrass, miscanhtus, and other perennials were assessed across a precipitation gradient in Kansas (465 mm of precipitation at Colby, 579 mm at Hays, and 838 mm at Manhattan). Bulk density, water retention, water infiltration and gravimetric water content were measured. Overall, preliminary observations suggest that switchgrass (Blackwell) may be the most adaptable in dryland conditions.