Biochars from Excelsior Woody Biomass Residues for Improved Poplar Production

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Standard pallets were made from farm-grown hybrid poplar and tested for durability compared to those made from other wood species and other pallet designs. Hybrid poplar had the advantages of shorter growth rotations, easier harvest, and lighter-weight pallets. However, the lower wood density of hybrid poplars make the pallets more susceptible to failure, especially when combined with lower quality nails or fasteners.

Dr. Catherine Brewer, Assistant Professor, Chemical and Materials Engineering, New Mexico State University (NMSU), Las Cruces, New Mexico, collaborated with Drs. Delia Valles-Rosales (NMSU), Koffi Djaman (Agricultural Science Center (ASC), Farmington, NM), and Michael O’Neill (ASC) to study ways to improve the sustainability of wood products in the south central region: using fast-growing hybrid poplar from farms instead of pine or Aspen harvested from forests, converting wood residues to biochar and renewable heat energy through the use of pyrolysis in production facilities, and using woody residue biochar to improve soils used to grow hybrid poplar.

Woody residue sources and amounts within the pallet production facility were modeled to evaluate waste reduction options and the cost-benefits of adding a pyrolysis process. An Arena software facility model was constructed for the pallet production process, including material flows, waste amounts, and worker time.

“Potential process changes can now be inputted into the model to estimate production outcomes as a decision making tool,” Brewer said. “Modeling results of the pallet production facility will be used to make recommendations for facility layout and waste management options,” Brewer added.

Several dozen pallets were also produced from hybrid poplar, which included enough standard pallets to enable comprehensive durability tests and to construct pallet performance computer models, and enough pallets of several sizes to enable in-application testing of the pallets by the pallet company’s customers.

“Durability tests and modeling results of the hybrid poplar shipping pallets will be used for recommendations to pallet manufacturers about what properties to seek in farm-raised hybrid poplar, and what adjustments must be made in pallet design and fastener selection to maximize pallet performance,” Brewer said.

“Feedback from the pallet performance model and the customer application tests indicate that further development of hybrid poplar pallets is warranted and of interest to pallet users,” Brewer stated. “The pallet company is now exploring more options for local woody feedstocks and for investments to reduce and better use current wastes. Our industry partners are more engaged with research and development, asking more questions to find out what could be done to improve their business outcomes in the long term,” Brewer added.

“We also used biochar from excelsior residues  to amend an alkaline agricultural soil, which was used to grow hybrid poplar and was irrigated at two different levels,” Brewer said. Early tree growth and changes in soil properties were measured over two growing seasons to evaluate the potential of biochar application in arid Southwest agroforestry systems. “There was a positive trend observed in soil water use efficiency and increased tree leaf growth in our study, though not statistically significant; we will use this result to guide our on-going longer-term and future biochar application studies in agroforestry,” Brewer added.

Funding of this project was provided by the U.S. Department of Agriculture-National Institute of Food and Agriculture (USDA-NIFA) through the South Central Sun Grant Program.