Simulating the feasibility of dual use switchgrass on cow-calf operations

Meeting biorefineries’ demands for lignocellulosic biomass will require sourcing feed-stock without affecting the food or animal-feed supply. A decision-aid model can assess the dual use of switchgrass (Panicum virgatum L.) to maintain animal production while providing biomass. We simulated a mixed-farm operation with 156 ha of hay+pasture, 96 beef cows (Bos spp.), and poultry (Gallus gallus L.) production wherein the hay land was converted to switchgrass for dual use as biomass and forage. The cow-calf simulator tracked changes in forage and cattle production, economic returns, and net greenhouse gas (GHG) emissions. Dual use of switchgrass consisted of harvesting the first cutting (mid-June) for hay and the second cutting (October-November) for bio-mass. Dual use required a modest increase in fertilizer application and supplementing cows with corn grain to meet nutritional requirements. Converting hay land to dual-use switchgrass produced 122 Mg of switchgrass, reduced net GHG emissions for autumn-and spring-calving operations by 3.4 and 3.6%, respectively, and increased the farm profit by approximately $1,500 when priced at $50 Mg⁻¹ regardless of the calving season. This simulation provided evidence that conversion of hay lands (in a beef cow-calf and poultry farm) to dual-use switchgrass can avoid displacing food pro-duction, while supplying bioenergy feedstock and reducing climate-forcing gases.