Agricultural Management of Switchgrass for Fuel Quality and Thermal Energy Yield on Highly Erodible Land in the Driftless Area of Southwest Wisconsin

Converting row crop production to a perennial grass crop on highly erodible land has numerous benefits. Switchgrass, grown as a biofuel crop, can provide soil conservation benefits as a perennial crop and also provide economic value to the grower. However, little information exists regarding switchgrass management and production on these lands. The objectives of this study were to determine the effect of two management practices, nitrogen (N) fertilizer rate (0, 56, 112, 168, and 224 kg ha^?1) and harvest timing (mid-fall, late-fall, and spring), on: (1) dry matter (DM) yield, (2) switchgrass quality components (moisture, ash, and chloride (Cl^?) concentrations), and (3) combustion energy content and yield. The study was conducted in 2009 and 2010 on highly erodible lands in the Driftless Area of southwest Wisconsin. Results showed a positive response of switchgrass DM to N fertilizer, with no yield gain above 112 kg ha^?1 of N, although application of N increased Cl^? concentrations. Harvest timing also affected switchgrass yield, with decreases in yield observed with progressively later harvest timings; this yield decrease was slightly greater compared with previous studies. Progressively later harvest timings led to a decrease in moisture, ash concentration, and Cl^? concentration in both years. Energy content of switchgrass was not significantly affected by management. Energy yields, similar to DM yields, were maximized with 112 kg ha^?1 of N with a mid-fall harvest. The similarities between this study and other research indicate there is a universal response of switchgrass to N in the northern USA and yields determined in this study indicate that highly erodible lands in the Driftless Area can be used to produce switchgrass at regionally expected yields.