Commercial forage harvest systems include those that produce (1) small bales; (2) large cylindrical solid bales; (3) large rectangular solid bales; (4) loosely chopped material; (5) pressed modules based on cotton module systems; and (6) chopped relatively wet material for ensilage

systems (Cundiff 1996; Cundiff and Marsh 1996; Worley and Cundiff 1996; Sokhansanj and Turhollow 2002; Gallagher et al. 2003; Kumara and Sokhansanj 2007). Given these conventional forage harvest technologies, for large volumes of dry matter, and to collect for field storage and transport substantial distances, large rectangular solid bales is the least-cost system for harvesting biomass from perennial grasses in the Southern Plains (Thorsell et al. 2004).

Table 5 includes an enterprise budget prepared to produce an estimate of the cost to produce biomass from an established stand of switchgrass (Epplin 1996). Established stands are expected to require no tillage or herbicide. Field operations are limited to fertilizer application, mowing with a self propelled windrower, and baling. Harvesting costs were based on an average yield of 8.97 dry Mg/ha/yr. The budget reflects a cost of $82.64/ ha for establishment with conventional tillage (from Table 3), $116.63/ha for fertilizer and fertilizer application, and $111.20/ha for land rent. The budgeted rate of fertilizer includes 90 kg/ha/yr of N and 22 kg/ha/yr of P2O5. Based on reported custom rates, the windrowing activity is budgeted to cost $33.56/ha and the baling activity $17.25/bale (Doye and Sahs 2012). Windrowing (mowing and preparing a windrow) is modeled as a per hectare cost while baling and hauling is modeled as a function of yield. The budget assumes that biomass is baled at 15 percent moisture into rectangular solid bales (1.22m x 1.22m x 2.44m, 635 kg), loaded, and transported from the

field by a tractor trailer truck. The key cost parameters are biomass yield, land rental rate, harvesting costs, and the cost to transport the biomass to a conversion facility.

Cost to transport is assumed to be a function of yield and distance. The average transportation distance from the field to the biorefinery is assumed to be 48 km. Wang (2009) estimated the cost of transportation specifically for moving biomass from a field to a conversion plant. She assumed that a standard flatbed trailer truck could carry an average load of 14.5 dry Mg. For a diesel fuel price of $0.79/L, Wang’s equation can be summarized as the cost $/dry Mg = 0.8796 + 0.1983 * km (one way distance).

Costs per hectare and costs per dry Mg are computed for yields of 4.48, 8.97, and 13.45 Mg dry matter/ha. The estimated breakeven costs are $65/Mg for a 13.45 dry Mg/ha yield and $121/Mg for a 4.48 Mg/ha yield. Table 6 contains a summary of findings to changes in the estimated breakeven price of biomass when the costs of several important cost items are doubled. For a yield of 8.97 Mg/ha, doubling the cost of land would increase the breakeven price by 17 percent from $79 to $92/Mg. Doubling the transportation cost would increase the breakeven price by 13 percent, and doubling the fertilizer cost would increase the cost by 16 percent. Doubling the cost to bale the material increases the cost by 34 percent if the

“Fertilizer is assumed to be applied in February or March.

bThe price of urea ($0.44/kg) is presented in the budget. This cost translates into a price of $0.96/kg of actual nitrogen.

cIf soil test values of phosphorus are sufficient, no P2O5 is recommended. The budgeted DAP application includes 9 kg N/ha and 22 kg P2O5/ha. The budget reflects the cost of 81 kg N from urea and 9 kg N from DAP to achieve the level of 90 kg of actual N/ha. dHarvest is budgeted to occur in October or November.

eAverage transportation distance is assumed to be 48 km. Estimated transportation cost is based on a diesel fuel price of $0.79/L and the equation ($/dry Mg) = 0.8796 + 0.1983 * km (one way) (Wang 2009).

yield is 8.97 Mg/ha and by 42 percent if the yield is 13.45 Mg/ha. By this measure, the estimated cost to deliver feedstock is sensitive to baling cost. The cost to deliver a flow of feedstock may depend critically on managing baling and other harvest cost.