Natural drying and dry matter loss of willow round bales during storage
Authors: Savoie, P, M-A Robert, F-S Robert, Pl H
Description: Willow grown in plantations is a perennial crop that regrows after cutting. It can produce large quantities of reliable biomass at rates of 10 to 15 t dry matter/ha/year in eastern Canada. An area of 1.57 ha of willow was harvested after a 2-year growth cycle in the form of round bales with a biobaler on November 24 and 25, 2010. A total of 174 bales were harvested. On average, bales measured 1.2 m wide and 1.2 m in diameter, weighed 373 kg and had a moisture content of 50.3%. The purpose of this experiment was to monitor storage changes over a 12-month period using three different methods. The first storage method was a pile of bales stored outside. The actual pile contained 108 bales in 9 sections of 12 bales. Each section included 5 bales directly on the ground, 4 intermediate bales just above and 3 bales on top sections were contiguous. The second storage method was based on 12 individual bales left outside on pallets. The third storage method was based on 12 individual bales placed inside a cold barn on pallets. The plan was to remove about one quarter of the stored bales and shred them individually in a tub grinder at four times after harvest: February, May, August and November 2011. In the winter, not all bales stored outside could be removed without severe loss or breakage because of snow cover and ice. Overall, the moisture content of bales stored outside decreased on average from 50% at harvest to 44% after six months, 37% after nine months and 32% after 12 months. Bales also lost a significant amount of dry matter, presumably due to oxidation, at an average rate of 1 to 2% per month depending on time of the year and bale position. Bales on the periphery of the pile and individual bales became drier than bales enclosed within the pile where moisture remained high, sometimes still at 45 to 50% after 12 months of storage. Improved storage methods are necessary for woody crops to minimize dry matter loss and to produce a relatively dry product at low cost.
Keywords: biomass, storage, drying, loss, handling, processing
Session name: Machinery