Compared to other lignocellulosic bioenergy crops, switchgrass rates well in its fertilizer, pesticide, and irrigation requirements (Groom et al. 2008). Switchgrass biomass does not appear to be sensitive to phosphorus (P) additions (Muir et al. 2001), and spring nitrogen (N) additions in some cases have had little effect on biomass outcomes when compared to control groups receiving no N at all (Thomason et al. 2005), consistent with switchgrass evolving in low N conditions. Other studies have shown N additions to increase biomass yields, but with diminishing returns such that N additions as low as 56 kg/ha having the highest fertilizer use efficiencies (Lemus et al. 2008). In a study based in Illinois, switchgrass production resulted in minimal N leaching compared to maize (1.4 kg N/ha/yr vs. 40 kg N/ha/ yr), and was slightly better in this capacity (though not statistically different) than Miscanthus x giganteus, a lignocellulosic alternative (Mclsaac et al. 2010). All evidence points towards switchgrass having excellent N-use efficiencies, and the ability to effectively partition nutrients to its roots towards the end of the growing season.

Water-use and water quantity and quality repercussions of switchgrass production are mixed. The amount of water used in the entire ethanol production process is not trivial, and can amount to > 2000 L water to produce 1 L ethanol in some locations (Chiu et al. 2009). This obviously brings forth the notion that areas of the world that rely heavily on irrigation (e. g., western U. S. states) may not be well-suited for future biofuel production. On the agronomic production side alone, evapotranspiration losses for all bioenergy crops are expected to increase in a warming and elevated-CO2 climate (Le et al. 2011). The jury is still out on how switchgrass compares to other bioenergy crop alternatives; some studies have shown that evapotranspiration losses for switchgrass are not as large of a problem as they are for Miscanthus x giganteus (McIsaac et al. 2010), while others essentially equate switchgrass with Miscanthus x giganteus but characterize them both as having higher losses than maize (Le et al. 2011). Subsequent alteration to the water cycle may have large impacts in areas that will experience conversion to bioenergy crop production. The impacts could well be tied to lower water quality via reduced surface runoff under certain land — use changes (Wu et al. 2012); however, models projecting sediment-, N-, and P-associated metrics indicate that perennial grasses, like switchgrass, may be better alternatives than row crops such as maize (Love and Nejadhashemi

2011) . Across large spatial scales, the water-use efficiency of switchgrass is notable; it is generally thought to be better than that exhibited by maize (VanLoocke et al. 2012), and undoubtedly will influence short — and long­term system-wide water quality and quantity issues.