Conservation of miscanthus in bale form

Because of the increased interest in miscanthus as a new source of biomass for energy production and fibre, in 2007 a field experiment was established to determine the optimum storage conditions for miscanthus in round bale form (1.2 m diameter × 1.2 m long). Miscanthus bales were stored under three treatments, outdoor uncovered, outdoor covered and indoor. The miscanthus bales were selected from three stands at three initial moisture conditions (13%, 32% and 39%) wet basis (wb). The storage trial was arranged in a 3 × 3 factorial experiment with two replicates laid out as a completely randomised design. Bale percent moisture content was repeatedly measured. Uncovered bales stored outdoors gained on average 24% moisture (wb), with resultant degradation of the material quality. Bales stored outdoors covered or indoors lost on average 4.3% and 6.8% moisture (wb) respectively. The energy content of bales stored outdoors uncovered was considerably lower than that of bales stored outdoors covered or indoors. The average lower heating value (LHV) of bales stored outdoors uncovered was 9.34 MJ kg−1 compared to a LHV 15.33 MJ kg−1 for bales under covered storage. It is concluded that miscanthus bales must be stored under cover either indoors or outdoors using plastic or tarpaulins to prevent deterioration of the bales and for drying to occur.