Methods of Constructing a Pine Tree Substrate from Various Wood Particle Sizes, Organic Amendments, and Sand for Desired Physical Properties and Plant Growth

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Additional index words. aged bark, air space, dynamic physical properties, evaporative method, fresh bark, particle size, Pinus taeda, porometer, sand, static physical properties, water holding capacity Abstract. Pine bark is the primary constituent of nursery container media (i.e., soilless substrate) in the eastern United States. Pine bark physical and hydraulic properties vary depending on the supplier due to source (e.g., lumber mill type) or methods of additional processing or aging. Pine bark can be processed via hammer milling or grinding before or after being aged from £1 month (fresh) to ‡6 month (aged). Additionally, bark is commonly amended with sand to alter physical properties and increase bulk density (D b ). Information is limited on physical or hydraulic differences of bark between varying sources or the effect of sand amendments. Pine bark physical and hydraulic properties from six commercial sources were compared as a function of age and amendment with sand. Aging bark, alone, had little effect on total porosity (TP), which remained at ' '80.5% (by volume). However, aging pine bark from £1 to ‡6 months shifted particle size from the coarse (>2 mm) to fine fraction (<0.5 mm), which increased container capacity (CC) 21.4% and decreased air space (AS) by 17.2% (by volume) regardless of source. The addition of sand to the substrate had a similar effect on particle size distribution to that of aging, increasing CC and D b while decreasing AS. Total porosity decreased with the addition of sand. The magnitude of change in TP, AS, CC, and D b from a nonamended pine bark substrate was greater with fine vs. coarse sand and varied by bark source. When comparing hydrological properties across three pine bark sources, readily available water content was unaffected; however, moisture characteristic curves (MCC) differed due to particle size distribution affecting the residual water content and subsequent shift from gravitational to either capillary or hygroscopic water. Similarly, hydraulic conductivity (i.e., ability to transfer water within the container) decreased with increasing particle size.

Section: Resultsmentioning

confidence: 97%

Physical and Hydraulic Properties of Commercial Pine-bark Substrate Products Used in Production of Containerized Crops

Altland¹,

Owen²,

Jackson³

et al. 2018

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“…As a result of the manufacturing process, SPW is a fibrous material with roughly frayed edges. These edges could have resulted in a higher percentage of fines (Table 2) and therefore a higher water-holding capacity (Handreck, 1983;Jackson et al, 2010;Richards et al, 1986). Fine-sized particles have much higher surface area than larger diameter particles.…”

Section: Discussionmentioning

confidence: 99%

Hydration Efficiency of Traditional and Alternative Greenhouse Substrate Components

Fields

Fonteno

Jackson

2014

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Wettability is a major factor in determining whether a material can be effectively and efficiently used as a component in greenhouse substrates. Poor wettability can lead to poor plant growth and development as well as water use inefficiency. This research was designed to test the wettability and hydration efficiency of both traditional and alternative components of substrates under different initial moisture contents (MCs) and wetting agent levels. Peatmoss, perlite, coconut coir, pine bark, and two differently manufactured pine tree substrate components (pine wood chips and shredded pine wood) were tested at 50% and 25% initial MC (by weight). The objective of this research was to determine the effects of initial MC and wetting agent rates on the wettability and hydration efficiency of these substrate components. Each component received four wetting agent treatments: high (348 mL·m−3), medium (232 mL·m−3), low (116 mL·m−3), and none (0 mL·m−3). Hydration efficiency was influenced by initial MC, wetting agent rate, and inherent hydrophobic properties of the materials. Wetting agents did increase the hydration efficiencies of the substrate components, although not always enough to overcome all cases of hydrophobicity.

“…It is well known that the hydraulic properties of roots vary with species and environmental conditions (Domec et al, 2004;Miyamoto et al, 2001), and these conditions can strongly influence root morphology and anatomy (Domec et al, 2010;Steudle and Peterson, 1998). Pine wood-based substrates generally involves the use of entire pine trees (i.e., bark, wood, cambium, and needles), which is a departure from using just pine bark (PB) in the greenhouse and nursery industry, and these wood-based substrates have been shown to have suitable physical and chemical properties (compared with PB or peat) while enhancing/increasing root growth Schnitzler, 2004a, 2004b;Jackson et al, 2010;Wright and Browder, 2005). With the reported increase in root growth of plants grown in wood substrates, measuring the hydraulic conductivity of root systems grown in substrates containing wood components may be insightful and help explain the growth increase/ substrate effect.…”

mentioning

confidence: 99%

Measuring Root Hydraulic Parameters of Container-grown Herbaceous and Woody Plants Using the Hydraulic Conductance Flow Meter

Judd¹,

Jackson²,

Fonteno³

et al. 2016

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Root hydraulic conductance and conductivity are physiological traits describing the ease with which water can move through the belowground vascular system of a plant, and are used as indicators of plant performance and adaptability to a given environment. The ability to measure hydraulic conductance of container-grown herbaceous and semiwoody plants with soft conductive tissue was tested using a hydraulic conductance flow meter (HCFM). Although the HCFM is a hydraulic apparatus that has been used on woody plants to measure hydraulic conductance of intact roots, it has never been reportedly used on container-grown horticultural plants. Two herbaceous species, Chrysanthemum L. and Solenstemon scutellarioides Thonn., were grown in containers and hydraulic parameters were measured, including root conductance and root conductivity, as well as physical traits such as stem diameter and dry root mass. The HCFM was easily connected to intact roots even on herbaceous stems and was used to determine hydraulic conductance and conductivity directly on container-grown plants with minimal disturbance on the root system. Chrysanthemums, Buddleja davidii Franch., and Hibiscus moscheutos L. were grown in three different substrates, and both root mass and root hydraulic parameters were determined. Chrysanthemums showed a positive response with increasing root hydraulic conductance with increasing root mass. The substrates used in these studies only had an effect on root biomass of chrysanthemums, but substrates had no differential effect on root hydraulic conductivity.