Wood and charcoal quality of four Eucalyptus clones at 108 and 120 months

ABSTRACT

Economic instability scenarios and reduction in charcoal consumption, such as those that occurred in 2009 and 2016, affect production and result in the maintenance of eucalyptus forests and an increase in the rotation age. The objective of this work was to evaluate the quality of wood from four Eucalyptus clones (clones 1, 2, 3, and 4) at the ages of 108 and 120 months and the charcoal produced in a rectangular kiln. We evaluated the heart/sapwood ratio, basic density, dry mass per hectare.year, and chemical composition . The carbonizations were performed in a rectangular kiln (210 m³ of wood). We determined the gravimetric yield and the charcoal properties: density, particle size and percentage of fines, friability index, proximate analysis, and mass of charcoal produced per hectare.year. We verified the significant effect of clones on basic density and dry mass, whose variations were from 494 to 589 kg m^-3 and 12.47 to 23.34 ton.ha^-1, respectively. The charcoal yield did not differ among clones (34.1%), while the yield of semicarbonized wood varied from 3.2% (clone 4) to 10.7% (clone 3). The particle size of 65% of the charcoal volume of clones 1 and 3 was greater than 30 mm, and 49.5% of clones 2 and 4. We found medium mechanical resistance for charcoal from all four clones. The apparent density ranged from 356 to 458 kg.m^-3, with the highest average value for clone 3. We found the highest charcoal production for clones 1 and 2, 7.5 tons per hectare.year. The fixed carbon did not vary among clones (76.92%). The wood properties of the Eucalyptus clones at ages 108 and 120 months are suitable for charcoal production for metallurgical use. Clones 1 (a hybrid of E. urophylla x E. grandis) and 3 (a hybrid of E. urophylla x E. camaldulensis) stood out from the others.

Keywords
Retangular kiln; Rotation age; Density