Dry matter loss and compositional analysis of large switchgrass round bales during ambient storage in Virginia

Two varieties of switchgrass, Cave-N-Rock and Alamo, were baled into 1.8-m diameter by 1.2-m wide round bales and stored outside for 12 months. String-wrapped bales were stored on sad and net-wrapped bales on rock. Six bales (three-string-wrapped, three netwrapped) were destructively sampled at four, eight, and 12 months. Samples were collected for moisture content and compositional analysis. As expected, there was a large moisture content gradient from the weathered layer to the inner core, depending on drying conditions since the last precipitation. In one instance weathered layer moisture content was three times the core moisture content Netwrapped bales were drier than string-wrapped bales. Negligible dry matter loss (DML) was reported at four and eight months for Cave-N-Rock with DML no greater than 7% after 12 months of storage. Calculated DML was highly variable but no more than 16% of original dry matter after 12 months of storage for Alamo. For one set of six bales (Cave-N-Rock, sampled at eight months), the calculated dry matter loss was negative (meaning the bales gained dry matter during storage). This result is physically impossible and illustrates the difficulty in accurately measuring dry matter loss. DML was less for net-wrapped bales on rock than string-wrapped bales on sod.