Water use and biomass yield of bioenergy crops in the North Carolina Piedmont

Crops grown for bioenergy purposes are a potential alternative to traditional row crops and pasture-hay systems in the North Carolina (NC) Piedmont, but there is limited information available about their biomass yields and water requirements in this region. The goal of this study was to evaluate biomass yield and water-use efficiency of switchgrass (Panicum virgatum L.), giant miscanthus (Miscanthus x giganteus Greef et Deu.), biomass sorghum (Sorghum bicolor spp.), silage corn (Zea mays L.) and tall fescue (Lolium arundinacea Schreb.). The perennial systems were established in 2012 while annuals were planted each spring. Crop water use was evaluated for the 2016 and 2017 growing seasons using a water balance approach. Giant miscanthus had the highest 2-yr average biomass yield (29.1 +/- 0.8 Mg ha(-1)) followed by corn (23.6 +/- 0.6 Mg ha(-1)) and biomass sorghum (22.0 +/- 1.8 Mg ha(-1)). Switchgrass and tall fescue had the lowest biomass yields, 14.2 +/- 1.9 and 12.5 +/- 1.2 Mg ha(-1), respectively. Fescue had the highest season-long water use in both years of the study. Perennial grasses giant miscanthus and switchgrass had similar seasonal water use, but giant miscanthus had higher water-use efficiency due to greater biomass yields. The annual crops corn and sorghum used less water than the perennial systems because of their shorter growing season, and, consequently, had higher water-use efficiencies. This information can aid growers when making management decisions about converting land into bioenergy crops.