Evaluation of eastern gamagrass as dual‐purpose complementary bioenergy and forage feedstock to switchgrass

Abstract

Switchgrass (SG) is considered a model bioenergy crop and a warm‐season perennial grass (WSPG) that traditionally served as forage feedstock in the United States. To avoid the sole dependence on SG for bioenergy production, evaluation of other crops to diversify the pool of feedstock is needed. We conducted a 3‐year field experiment evaluating eastern gamagrass (GG), another WSPG, as complementary feedstock to SG in one‐ and two‐cut systems, with or without intercropping with crimson clover or hairy vetch, and under different nitrogen (N) application rates. Our results showed that GG generally produced lower biomass (by 29.5%), theoretical ethanol potential (TEP, by 2.8%), and theoretical ethanol yield (TEY, by 32.9%) than corresponding SG under the same conditions. However, forage quality measures, namely acid detergent fiber (ADF), crude protein (CP), and elements P, K, Ca, and Mg were significantly higher in GG than those in SG. Nitrogen fertilizer significantly enhanced biomass (by 1.54 Mg ha−1), lignin content (by 2.10 g kg−1), and TEY (787.12 L ha−1) in the WSPGs compared to unfertilized treatments. Intercropping with crimson clover or hairy vetch did not significantly increase biomass of the WSPGs, or TEP and TEY in unfertilized plots. This study demonstrated that GG can serve as a complementary crop to SG and could be used as a dual‐purpose crop for bioenergy and forage feedstock in farmers' rotations.

Photosynthetic responses of switchgrass to light and CO2 under different precipitation treatments

“…Notably, it possesses favorable attributes, including lower nutrient demands and high below‐ground carbon sequestration, making it a model bioenergy crop (Adler et al., 2006; Albaugh et al., 2014; Liu et al., 2022; Parrish & Fike, 2005; Ricketts et al., 2023; Rinehart, 2006). Extensive research has explored the effects of agricultural practices like nutrient applications, irrigation, and cutting systems, on switchgrass productivity (Hui et al., 2018; Keyser et al., 2022; Kieffer et al., 2023; Lemus et al., 2008; Miesel et al., 2017; Wullschleger et al., 2010). However, there have been limited studies focused on understanding the impacts of climate change, such as changes in precipitation, on switchgrass, particularly in field conditions (Deng et al., 2017; Hartman et al., 2012; Hartman & Nippert, 2013; O'Keefe et al., 2013).…”