Evaluation of Distilled Eastern Red Cedar (Juniperus virginiana L.) as an Alternative Substrate Component in the Production of Greenhouse-Grown Annuals
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Peat moss and perlite are the core components found in soilless greenhouse substrates today and are thus in high demand commercially. Due to both environmental and economic concerns associated with peat harvest and production, and the health and economic concerns accompanying perlite, there has been an increase in research efforts concerning alternatives. A majority of the viable alternatives available to growers are wood based substrates. Many of these substrates are readily available and could be considered more sustainable, depending on geographic location. Recently, eastern red cedar (Juniperus virginiana) has been considered as a potential alternative. The cedar used in these experiments was obtained from CedarSafe, an exporter of cedar oil for the perfume industry and closet lining. Eastern Red Cedar logs (Juniperus virginiana L.) arrive at the facility and are debarked. The logs are then shaved and the shavings are sent through a hammer mill to pass a 1.27 cm screen (0.5 in). The milled cedar is then conveyed to a set of boilers where it undergoes a steam distillation process. This process extracts a percentage of the oil from the milled particles. The oil is then sequestered and sold to varying business markets. CedarSafe is left with this post-distilled cedar biomass that has no marketable value. However, our research aims to determine if post-distilled cedar can be used in proportional combination with peat moss in order to produce a successful greenhouse substrate. The objective of our first experiment was to incorporate post-distilled cedar, in varying volumetric concentrations, as a substrate component and compare it to a grower’s standard peat-lite mix. There were six treatments implemented: 100% peat-lite (PL), 20:80 cedar (C):PL, 40:60 C:PL, 60:40 C:PL, 80:20 C:PL, and 100% C. From our collected data we observed that substrates containing up to 40% cedar had equal if not better growth for petunias (Petunia ×hybrida ‘Celebrity Blue’) and impatiens (Impatiens walleriana ‘Extreme Violet’) than the standard peat-lite mix. Therefore, growers could amend their substrates with up to 40% cedar and see little to no change in marketable plant growth. In a second experiment, post-distilled eastern red cedar was compared to a pre-distilled eastern red cedar substrate. Pre (C) and post-distilled cedar (DC) were mixed, in volumetric combination, with an industry standard peat moss (PM). The six treatments formulated in this experiment included: 60:40 C:PM, 40:60 C:PM, 20:80 C:PM, 60:40 DC:PM, 40:60 DC:PM, and 20:80 DC:PM. The substrates were planted with either petunia (Petunia ×hybrida ‘Dreams Burgundy’) or vinca (Catharanthus roseus ‘Cooler Rose’) placed in a greenhouse and watered as needed until termination. Data taken after termination indicated that DC substrates performed equal to, if not better than, C substrates. This could be due, in part, to the distillation process that our cedar biomass undergoes. The act of removing a percentage of the cedar’s oil, and the high heat involved, may positively affect DC substrate characteristics and result in superior plant growth. This cedar could potentially be a viable alternative for the horticulture industry and replace portions of PM and perlite in the production of greenhouse annuals. The objective of our final study was to mimic the beneficial characteristics of perlite in substrates by adding distilled cedar and rice hulls to peat moss and comparing them to peat-lite mixes of concordant percentages. Treatments were amended at 10%, 20%, and 30% for each component. The species used included petunia (Petunia ×hybrida ‘Dreams Sky Blue’) and marigold (Tagetes erecta ‘Antigua Yellow’). Petunia results indicated that PL treatments performed marginally better than substrates containing DC and RH in one of the two experiments. However, for marigold, no difference was observed between treatments in almost all growth parameters for both experiments. The data indicated that growers could substitute DC or RH for P and yield viable annual crops.