Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2010
Publication Date: 7/10/2010
Citation: Altland, J.E. 2010. Use of Processed Biofuel Crops for Nursery Substrates. Journal of Environmental Horticulture. 28:129-134.
Interpretive Summary: Decreasing availability and increasing price for pine bark is a growing concern among nursery producers east of the Rocky Mountains. Alternatives to pine bark are needed. While agricultural and manufacturing industries once generated large volumes of waste or residual materials (for example, pine bark), ever-growing interest in bio-energy has greatly reduced availability of those materials. The abundance of farmland in most of the nursery-producing regions of the U.S. led us to consider the concept of harvesting biofuel crops and processing them into a substrate. The objective of this research was to determine if several commonly grown biofuel crops could be processed and amended to produce a substrate suitable for production of containerized ornamental plants. Switchgrass (Panicum virgatum), willow (Salix spp.), corn (Zea mays) stover, and giant miscanthus (Miscanthus ×giganteus) were processed through a hammermill equipped with a 0.95 cm (0.375 in) screen. Pine bark was used as a control. All materials were used either alone, amended with 20% (v/v) sphagnum peat moss, or amended with 20% (v/v) sphagnum peat moss and 10% (v/v) municipal solid waste compost. Plant growth was acceptable in all biofuel-based substrates, however, chemical and physical properties for each substrate will require some modification.
Technical Abstract: Loblolly pine (Pinus taeda) bark availability has decreased, causing shortages in inventory and increased prices for pine bark substrates. One potential alternative to pine bark is the use of biofuel or biomass crops that can be grown locally, harvested, and processed into a suitable substrate. The objective of this research was to assess the suitability of several biofuel crops as alternatives to pine bark in nursery substrates using annual vinca (Catharanthus roseus) as a model crop. Across two experiments, switchgrass (Panicum virgatum), willow (Salix spp.), corn (Zea mays) stover, and giant miscanthus (Miscanthus ×giganteus) were processed through a hammermill equipped with a 0.95 cm (0.375 in) screen. Pine bark was used as a control. Substrate materials were used either alone, amended with 20% (v/v) sphagnum peat moss, or amended with 20% (v/v) sphagnum peat moss and 10% (v/v) municipal solid waste compost. Biofuel-based substrates tended to have greater air space and less container capacity than pine bark substrate. Amending with peat moss, or peat moss and municipal solid waste compost reduced air space and increased container capacity of all substrates. Substrate pH of biofuel-based substrates was higher than pine bark substrates, and was neutral to slightly alkaline. Amending with peat moss reduced pH of biofuel substrates to levels considered more ideal for annual vinca growth. Foliar calcium, magnesium, and iron levels were low across all treatments, although visual foliar deficiency symptoms were not apparent. Shoot growth was greatest in switchgrass and pine bark substrates. Plant growth was acceptable in all biofuel substrates, however, modification of chemical and physical properties for each substrate type will be necessary.