The storage of logging residue for fuel

Abstract The effect of storage on the fuelwood properties of Norway spruce logging residue were studied. The characteristics under study included moisture and needle content, and elemental composition. Storages included uncomminuted residue piles on the clear-cut left by single grip harvester, uncomminuted residue in large windrows at road side landing and as a third alternative a comminuted, compacted and non-compacted residue piles at a terminal. The initial moisture content of fresh residue was 56% on green weight basis. After one-year storage the residue at the clear-cut had reached an average moisture content of 28.5 and 42.2% at the landing. The moisture content of comminuted material had risen to 65.3% during nine-month storage. The original needle content of fresh logging residue was 27.7% and one year later it had decreased to 6.9% on the clear-cut and to 18.9% on the landing. The carbon content of the comminuted material had increased significantly from 50.0% to 51.1–51.3%. Simultaneously hydrogen content had decreased from 6.6 to 5.7%. Compaction had no significant effect on the carbon-hydrogen ratio. However, compaction did decrease pile temperature indicating lower dry matter losses in the compacted pile. The release of nutrients from the needles is slow. From the soil nutrition point of view, the shedding of needles is a more important factor than release of nutrients from the needles intact.