In-field performance of hay balers using DGPS

Herbaceous biomass in the southeast will contribute significantly to meeting U.S. renewable energy goals. Harvesting equipment for hay is generally suitable for mowing, raking, and baling grasses for bioenergy, such as switchgrass; however, there is a need for field data to better understand machine performance in energy crops. The purpose of this study was to collect field data to estimate baler throughput and speed. Data gathered with a DGPS unit during baling provided time-motion studies of baler productivity. Five fields were used to compare field capacity, speed, and throughput results from four round balers. The results showed that projected baler performance (from ASABE Standard estimates) was overestimated when the yield, maximum throughput, and wrap-eject time were not correctly accounted for. In the densest windrows, a baler encountered a maximum throughput beyond which increases in yield did not provide increases in baler productivity (t h^-1). Assuming that baler productivity increases linearly with increasing yield, an assumption of many models, is only valid at yields below this maximum throughput. At high yields, the measured values of throughput were up to 50% lower than the calculated throughput.