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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #344221
Title: Suitability of sphagnum moss, coir, and douglas fir bark as soilless substrates for container production of highbush blueberry

Author
item KINGSTON, PATRICK - Oregon State University
item Scagel, Carolyn
item Bryla, David
item STRIK, BERNADINE - Oregon State University

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2017
Publication Date: 12/18/2017
Citation: Kingston, P.H., Scagel, C.F., Bryla, D.R., Strik, B. 2017. Suitability of sphagnum moss, coir, and douglas fir bark as soilless substrates for container production of highbush blueberry. HortScience. 52(12):1692-1699. https://doi.org/10.21273/HORTSCI12374-17.

Interpretive Summary: The purpose of the present study was to investigate the suitability of different soilless substrates for container production of highbush blueberry. The plants were grown in media containing varying proportions of peat moss, coconut coir, and fir tree bark, all of which are commonly used by the plant nursery industry and are readily available to growers and homeowners. Both peat and coir resulted in vigorous plant growth and appeared to be good substrates for blueberry. Bark, on the other hand, was less suitable, particularly when it exceeded 30% of the total media composition. Inadequate irrigation likely played a role in poor plant growth in bark. Bark also reduced plant uptake efficiency of essential plant nutrients, including nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, manganese, and zinc. Next, we will evaluate the effects of using various amounts of perlite (an inert material used to increase aeration and drainage in potting media) with peat and coir and see if it will further improve growth and production of blueberries in containers.

Technical Abstract: The purpose of the present study was to investigate the suitability of different soilless substrates for container production of highbush blueberry (Vaccinium sp.). Young plants of ‘Snowchaser’ blueberry were grown in 4.4-liter pots filled with media containing 10% perlite and varying proportions of sphagnum peat moss, coconut (Cocos nucifera L.) coir, and douglas fir [Pseudotsuga menziesii Mirb. (Franco)] bark, as well as a commercially-available mix of peat moss, perlite, and other ingredients for comparison. Total dry weight of the plants was similar among the treatments at 72 days after transplanting, but at 128 days, total dry weight was nearly twice as much in the commercial mix and in media with 60% or more peat or coir than in media with high a proportion of bark. Inadequate irrigation likely played a role in poor plant growth in bark. Bark had lower porosity and water holding capacity than peat, coir, or the commercial mix and, therefore, dried quickly between irrigations. Bark also reduced plant uptake efficiency of a number of nutrients, including N, P, K, S, Ca, Mg, Mn, B, Cu, and Zn. Uptake efficiency of P, K, and Mg also differed between plants grown in peat and coir, which in most cases was a function of the initial concentration of nutrients in the media. Prior to planting, peat had the highest concentration of Mg and Fe among the media, while coir had the highest concentration of P and K. Leachate pH was initially lowest with peat and highest with coir but was similar among each of the media treatments by the end of the study. Electrical conductivity of leachate never exceeded 0.84 dS/m in any treatment. Overall, peat and coir appear to be good substrates for container production of highbush blueberry. Bark, on the other hand, was less suitable, particularly when it exceeded 30% of the total media composition.