Harvesting Systems for Short Rotation Coppice Crops Influence Cost, Performance, and Biomass Quality

Harvesting in short rotation coppice (SRC) systems occurs every 2-4 years with recommendations focusing on dormant season harvest. Because harvesting occurs on short rotations and five to seven times during the life of a crop it is both a significant source of greenhouse gas (GHG) emissions and costs for production. Two main approaches to harvesting short rotation coppice (SRC) have been developed, single-pass cut-and-chip systems and multi-pass systems. Single-pass systems have received the most attention and development over the past couple of decades and recommendations have focused on harvesting SRC during the dormant season. Single-pass harvester throughput is related to the standing biomass and with good ground conditions and standing biomass of over 60 Mg ha-1, throughput can range from 60 to 90 Mg h-1. However, changing weather patterns have required landowners to harvest during the growing season, which can reduce harvester throughput by 28-59% and increase the moisture and ash content of the biomass produced. Wet ground conditions also reduce throughput and increase crop specific fuel consumption. Harvester performance during the growing season or with wet ground conditions increases GHG emissions and costs. Variability in modeled costs for supplying large-scale biorefineries are attributed to standing biomass, and seasonal ground and crop conditions. While significant progress has been made in developing SRC harvesting systems, there is still room for improvements in harvester performance especially at different times of the year and under varying ground conditions.