Biorefineries face logistical problems that may affect the price a biorefinery is willing to pay. One of the driving factors in storage and transportation of biomass is the moisture content (MC) at harvest. Delaying switchgrass harvest from profit-maximizing times of October through November, when moisture and nutrient concentrations of the standing crop are still high, to January or February, when moisture in the standing crop has declined and more nutrients have translocated back to the roots of this perennial plant, may result in production cost savings at the expense of lower yield. Using 20 and 30% MC thresholds in the standing crop as a determining factor, harvesting requires a separate cutting pass above this threshold to allow drying in the swath before chopping with a forage harvester. Below that threshold, a forage harvester may be equipped to perform both cutting and chopping functions in a single pass. Using switchgrass trial data from several environments, this study calculates harvest date-driven changes in yield, harvest cost and nutrient replacement between a profit-maximizing harvest date, requiring two harvest equipment operations vs. delayed, single-pass harvest at lower standing crop MC of 30% and 20% to show whether delayed harvest is feasible.


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