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Aerobic and Anaerobic Storage of Single-pass, Chopped Corn Stover

Shinners, Kevin J., Wepner, Aaron D., Muck, Richard E., Weimer, Paul J.
Bioenergy research 2011 v.4 pp. 61
aeration, aerobic conditions, air, anaerobic conditions, bags, biomass, combustion, corn cobs, corn husks, corn stover, drying, feedstocks, harvesters, harvesting, heat, storage, storage conditions, temperature, water content
Corn stover has great potential as a biomass feedstock due its widespread availability. However, storage characteristics of moist corn stover harvested from single-pass harvesters have not been well quantified. In 2007, whole-plant corn stover at 19.1 to 40.3 % (w.b.) moisture content was stored for 237 days in aerobic piles, one covered and one uncovered, as well an anaerobic silo bag. In 2008, two stover materials – whole-plant and cob/husk from 31.7 to 58.1% (w.b.) moisture – were stored for 183 or 204 days in covered and uncovered aerobic piles, ventilated bags, or anaerobic silo bags. Stover stored in uncovered piles was rehydrated by precipitation, which increased biological activity resulting in DM losses from 8.2% to 39.1% with an average of 21.5%. Stover in covered piles was successfully conserved when the average moisture was less than 25% (w.b.) with DM losses of 3.3%. Stover above 36% (w.b.) moisture and piled under a plastic cover had DM losses from 6.4% to 20.2% with an average of 11.9%. Localized heating lead to temperatures where spontaneous combustion might be a concern (i.e. > 70°C) occurred in the aerobic piles when moisture was above 45% (w.b.). Ambient air blown through a center tube in the ventilated storage bag dried stover near the tube to an average of 24.2% (w.b.), but the remainder of the bag averaged 46.8% (w.b.) at removal. Loss of DM ranged from 7.4% to 22.0% with an average of 11.8% with this storage method. Stover was most successfully conserved in the bags where anaerobic conditions were maintained. Under anaerobic conditions DM losses ranged from 0.2% to 0.9%. When anaerobic conditions were not maintained in the silo bag DM losses averaged 6.1% of DM. Anaerobic storage is the best solution for conserving the value of moist corn stover.