BIOMASS LOSSES DURING HARVEST AND STORAGE OF SWITCHGRASS

Estimates of dry matter losses during harvest and storage of herbaceou s biomass are needed to determine harvest efficiency and net biomass y ield. Losses of switchgrass (Panicum virgatum L.) biomass stored in la rge round bales as affected by protected and unprotected conditions in three experiments during 1992 to 1995. We also measured the losses of dry matter (DM) during the harvesting operation each year and determi ned the quantity and quality of runoff water from stored bales during one year. In Experiment 1, ''Alamo'' switchgrass was harvested in Augu st 1992 and stored in 275 kg bales unprotected outside on a grass sod for six months. In Experiments 2 and 3, switchgrass was harvested in N ovember of 1993 and 1994, respectively, and stored in 370 kg bales for one year inside on concrete, outside on a grass sod unprotected from the elements, or outside on a gravel pad. In each experiment, the biom ass was field dried to 11 to 19% moisture and baled. The bales were we ighed at the beginning and end of the storage period to determine DM l osses. In Experiment 1, DM losses during six months of storage were 13 % of the original bale dry weight. In Experiments 2 and 3, there were no differences (P > 0.05) in DM losses (average of 5%) among outside t reatments during the 12 months of storage. There were no biomass Losse s for bales stored inside in Experiment 2; however, there was a 2% los s in Experiment 3. Losses of DM during baling ranged from 1 to 5% depe nding on moisture concentration in the biomass at baling. Larger losse s were associated with drier biomass, presumably because of more shatt ering. Quality and quantity of runoff water from bales were not differ ent (P > 0.05) from runoff water of control plots. (C) 1997 Elsevier S cience Ltd.