White Paper- Feasibility of Horticultural Wood Fiber Production in the Western US Forests, to Promote Fuels Reduction
by Jeff Greef, Plumas Wood Fiber Group
Peat moss and coir (coconut husk) have been mainstays of the commercial agricultural growing industry as substrates for soilless growing media in broad applications from commercial nurseries to retail potting mix sales since WWII. Demand for growing media is predicted to double, or quadruple, by 2050, creating concern among growers for availability of such substrate materials. Beginning in 1980 in France, but primarily the last several decades, interest has turned to wood fiber as a supplement or replacement for peat and coir. Many large commercial producers of growing media in the US and Europe are now making and selling wood fiber in their mixes, with excellent results.
Sawdust and chips will not work as growing media. Special processing methods are employed to break down wood from chips into long-fiber, spongy consistencies appropriate to the needs of growing media. In these processed conditions, the wood fiber closely resembles peat and coir for both water retention and aeration characteristics. Disadvantages are easily dealt with.
When wood fiber is sourced locally, cost can be significantly lower than peat and coir which have higher transportation costs due to their source locations. Processed wood fiber sequesters carbon, whereas disturbing peat bogs for harvest releases carbon, and transport carbon footprint is high for peat and coir. As well, supporting forest fuels reduction projects by removing chips for commercial sale reduces the severity of wildfires, resulting in carbon retained in healthy post-fire forests.
Studies have proven that coniferous woods produce the best quality wood fiber for growing media. As well, sapwood is favored for the best characteristics. Fuels reduction work in the western US forests focuses on removal of smaller coniferous trees, which have a greater proportion of sapwood to heartwood. Utilization of such small diameter, thinned material as a base stock for production of growing media will provide enough value to thinning chips to help motivate commercial thinning operations, while providing a lower cost alternative to the California agricultural industry that uses soilless growing media. Producers of wood fiber growing media are well established in Europe and some in the US east, but not yet in the US west, though California has the largest agricultural industry of any single US state.
Scope and Scale
World peat production yearly- 30 million metric tons
US consumption of peat yearly- 1.8 million metric tons
California consumption of peat yearly- approx. 200,000 metric tons (as a proportion of total US agricultural production).
If 10% of California peat consumption yearly was replaced with wood fiber, industry would have to deliver approx. 20,000 tons of wood fiber, or 1300 truck loads yearly.
Currently in the horticultural industry that uses wood fiber, 10 to 40% mixes of wood fiber with peat moss are used.
Peat Moss, Coir and Wood Fiber- Comparison
Around WWII peat moss came into predominant use for growing media, due to its excellent moisture retention and aeration characteristics. Peat moss mining is now limited, and in some places prohibited, in the UK and Europe where it has been mined for years, because of various environmental concerns. This has spurred the increased use of wood fiber as a growing media substrate in Europe and the UK. Canada is the primary source for peat moss in North America and has large quantities of peat. However, concern has arisen that peat bogs as carbon sinks should be left intact. As well, peat harvesting is dependent upon variable weather factors and supply has sometimes been reduced for periods of time. Transportation costs for peat are high. For these reasons confidence in the future reliable and economical availability of peat is low.
Coir comes from the extensive coconut groves of the Southern Hemisphere, and is considered renewable and plentiful. It must be properly washed of salts for use as a growing medium. It will always have certain transport costs, coming from afar, as well as possible supply chain issues. Its carbon footprint due to transport distance is greater than that for wood fiber.
Wood chips for making wood fiber are plentiful in the forests of the American West and elsewhere around the world. It is renewable and sustainable to harvest, and works well in conjunction with fuels reduction projects for wildfire mitigation. Logging operations and sawmills are an abundant source. Both the science and practical experience of wood fiber use as a substrate for growing media are beyond initial stages of development, though it is still relatively new and not as well-known as peat and coir. Due to its close proximity to the California agricultural industry, wood fiber from Western forests would have lower transportation costs and supply chain issues in comparison with peat and coir. Wood fiber sent to the ag industry is sequestered carbon that will not reenter the atmosphere as CO2 for years.
While wood fiber generally has similar water retention and aeration characteristics to peat and coir, it differs in other respects:
-ph is more acidic, which can be dealt with using lime.
-some sulphur is required, supplements are inexpensive.
-wood can absorb nitrogen, sometimes requiring growers to increase nitrogen feeding.
-other nutrient absorption characteristics differ and must be dealt with according to specific needs.
-use of green logs can be problematic, with toxins sometimes present in high amounts. Processing chips into fiber usually removes these toxins.
-sterilization of the wood fiber may be necessary to remove undesirable fungi or bacteria.
As with all growing media mixes, the proportions of ingredients in the mix as well as regimens of watering and feeding must be tailored to the specific needs of the species grown, taking into consideration how that species responds to the mix being used. Science and experience have shown that wood fiber is no more difficult to use than peat or coir, and its use is easily adapted to growing various plant species. In many cases, wood fiber use increases root growth rates.
Companies Currently (or soon) Producing and/or Selling Wood Fiber Growing Media
US and Canada
-Berger Peat is a major peat moss producer in Canada which also uses wood fiber
-Profile Products of Illinois produces Hydrafiber brand in North Carolina
-Pindstrup, Danish company marketing their product, Forest Gold, in the US.
-Scotts Miracle Grow.
-Several more US companies soon entering production, all east of the Rockies.
Europe, UK and elsewhere
-Klasmann-Deilmann, Germany, a major producer for decades, produces Greenfiber brand
-Floragard and Kleeschute in Germany.
-BVB, producer in Netherlands
-Florentaise in France produces Hortifibre brand
-Premier Tech in France.
-Melcourt Industries in the UK produces Sylvagrow brand
-Westland Horticulture in UK.
-One facility in each New Zealand and Australia.
-Promeco in Italy.
Science and Industry Media
Extensive scientific studies have been conducted on the use of wood fiber for growing media, and research is continuing. The following webinars and articles reflect this research;
-Webinar with Dr. Glenn B. Fain, Auburn University, and Daniel Norden, Senior R+D Developer, Profile Products, maker of Hydrafiber
-2021 Webinar with Dr. Brian E. Jackson of North Carolina State University, with extensive info on wood fiber use in horticulture. Dr. Jackson has researched use of wood fiber for growing media for years and works with the Horticultural Substrates Laboratory at NCSU, the only university facility currently producing wood fiber for research into its use as growing media.
-2015 Webinar with Dr. Brian E. Jackson of NCSU, a basic intro to wood fiber.
-Article by Dr. Jackson
-Article by Dr. Jackson
-Policy statement from the Royal Horticultural Society on peat extraction
-Science paper from the Royal Horticultural Society on peat alternatives, see sec. 4.1
-Magazine article on Hydrafiber
Special processing methods must be used to break the wood down into long wood fibers which are best for use as a growing medium. Three main processes are used:
1- Twin screw extrusion- chips are fed through turning, interlocking steel screws which crush the chips to separate the fibers. Expensive, multi-million dollar industrial installation.
2- Twin disk refiners- chips are fed between two large circular plates, one of which is fixed and the other turning. Chips are abraded between the plates to separate the fibers. Similar to paper pulp production. Expensive, multi-million dollar industrial installation.
3- Hammer Mill- Common technology used to chop bark etc., can be adapted for wood fiber growing media use. Less expensive alternative, generally lower volume production than the above technologies.
Different techniques, and different settings with each technique, will yield different grades of size, coarseness or fineness, etc. of the wood fiber. This allows a variety of different characteristics to be achieved in a growing medium, giving growers options according to the needs of their specific plants grown.
These processing techniques are shown briefly in Dr. Jackson’s webinars referenced above.
Proposed actions in Plumas County California
Scale Production- Development of a medium scale facility to process chips from fuels reduction projects, making disposal of biomass easier for fuels managers and fuels reduction project coordinators. A facility processing chips at a rate of 20 yards per hour would receive 200 tons wood chips per week and ship out 10-12 semi-trailers per week of finished, baled and palleted growing media to sell to the ag industry, paying the costs of operating the facility. 10,000 tons yearly. The proposed machinery to be purchased and installed is manufactured by Premier Tech of Quebec, and their subsidiary Slootweg Machine of Holland. The machine is designed specifically for the purpose of processing wood chips into wood fiber growing media, operates at a rate of approx. 20 yards per hour producing finished fiber media. A baler and palletizer will be utilized to complete the production line. Cost of these machines in total is below $2m. Other costs to implement the project will include site acquisition costs, building costs, fork lifts, loaders, etc.
Plumas County 2021 Wildfires Long Term Recovery Plan- project has been included by the Plumas Planning Department and others in current economic development plans.
Plumas Wood Fiber Group- Formed in Fall of 2022, the group believes that wood fiber growing media can be a viable use of biomass in Western forests, and seeks to implement a project to demonstrate this viability. The following individuals constitute the group:
-Dr. Brian Jackson, North Carolina State University Raleigh, Horticultural Substrates Laboratory.
-Jack Bobo, NC State Doctoral Candidate.
-John Sheehan, Plumas County Resident with extensive local planning/development experience.
-Dr. Cindy Chen, University of California Extension, woody biomass and wood products advisor.
-Sally McGowan, Board of Directors, Plumas Fire Safe Council
-Kevin Danaher, Co-founder, Global Exchange
-Paul Mrowczinski, grant writer/planner
-Jeff Greef, retired building inspector
Initial Research- Professor Jackson of NCSU (see above) is conducting research on five species of Western conifers to determine their viability for use as processed growing media. He states that such research on these species has never been done. Professor Jackson has been supplied with the chips needed for this research. The species are yellow pine, sugar pine, Douglas fir, white fir, and incense cedar. The research is being conducted by Dr. Jackson and his students through the NC State Horticultural Substrates Laboratory in Raleigh, and should be completed by Fall 2023 for submittal to peer reviewed academic journals.
Marketing and Feasibility Studies- the project must be evaluated for viability with appropriate marketing, feasibility and cost analysis studies. Critical to the project is determining interest and potential sales of the product in the agricultural sector. Hard marketing info and letters of interest from buyers of growing media must be obtained. A price point for sale of the material must be determined. Secondly, assessment of feedstock availability must be done to ensure the capability of fuels managers to supply the facility with a steady stream of wood chips. Finally, facility process operation costs must be closely detailed as part of an overall economic feasibility assessment. A proposal for such a study has been obtained from consultants Highland Economics and The Beck Group.
About the author- Jeff Greef is a retired building inspector and volunteer with the Plumas Fire Safe Council and the Plumas Underburn Cooperative in Plumas County, Ca. His house was saved from the Dixie Fire of 2021 by the practices of those two organizations. He now works to promote forest thinning and underburning to reduce the severity of fire effects from wildfire.
Contact the author at firstname.lastname@example.org