Evaluation of two forage harvesting systems for herbaceous biomass harvesting

Machine field efficiency, fuel consumption, and operating costs are important aspects of biomass harvesting. Two harvesting systems were selected and examined through harvesting alfalfa (hay and silage), wheat straw, and switchgrass. One harvesting system consisted of a typical forage harvester and several forage trucks depending on the distance between the field and dump site; the other system was a self-loading/chopping forage wagon. Both systems picked up windrows prepared by a mower and a windrow merger or rake. Mowing and windrow preparation equipment were not included in the evaluation of these two systems. Moisture content (10% to 75%) and distance from field to dump site (0 to 8.5 km) were varied. These two systems were operated in adjoining fields of known area. The cycle time, weight of material picked up, and diesel fuel used by each system were recorded. The fuel use per weight of alfalfa to harvest an 8.5 km field from the silo was 2.53 and 5.59 L Mg^-1 DM for the wagon and forage harvester systems, respectively, when adjusted for chop length. The wagon system required fewer operator hours to harvest a similar amount of material, but the harvester system harvested material at a faster rate of 12.3 Mg DM h^-1 compared to the wagon's 7.3 Mg DM h^-1. The wagon yielded a much longer chop length than the harvester.