Component and particle-size effects on shrinkage of two-component potting media were determined. Milled pine bark-sand mixtures were used to determine particle-size effects on shrinkage. Shrinkage curves formed an inverted V with maximum shrinkage at the 1:1 (v/v) ratio. No shrinkage occurred when bark was mixed with bark or sand with sand. Shrinkage increased linearly in the range of 0% to 50% bark and decreased linearly in the range of 50% to 100% bark. Each half of the shrinkage curve was a mirror image of the other half. Shrinkage curves for peat-sand and peat-perlite were similar in form to that of bark-sand media.
Colorful baskets of flowering annuals are popular with home gardeners, but these containerized plants require frequent waterings. Mulching of field soils is a proven way to conserve soil moisture. This study was conducted to see if mulching would reduce the need to irrigate containerized plants. Adding either pine bark or sphagnum moss mulch to potted `Impulse Rose' impatiens (Impatiens wallerana) plants reduced the frequency of irrigations when the plants were small and had not yet reached canopy closure. Mulching had no effect on plant height or flowering.
Sulfur (S) is essential to the growth of higher plants; however, research on S fertilizer requirements for container-grown nursery tree species has not been established. The purpose of this study was to determine the substrate solution S concentration that maximizes the growth of container-grown pin oak (Quercus palustris Münchh) (pin oak–K2SO4 experiment) and japanese maple (Acer palmatum Thunb.) (japanese maple–K2SO4 experiment) in a pine bark (PB) substrate. Both species were fertilized with solutions supplying a range of S concentrations (0, 1, 2, 5, 10, 20, 40, or 80 mg·L–1) using K2SO4. Regression analysis revealed that dry weights of both species were near maximum at the predicted application concentration of 30 mg·L–1 S, which corresponded to about 15 and 7 mg·L–1 S in substrate solution for pin oak and japanese maple, respectively. In a Micromax, FeSO4, lime experiment, S was supplied to pin oak via a preplant micronutrient sulfate fertilizer or FeSO4 in limed or unlimed PB. When the PB pH was relatively low (4.5, unlimed), FeSO4 and the preplant micronutrient fertilizer were effective in supplying ample S. However, when the PB pH was relatively high (6.1, limed), the preplant micronutrient fertilizer with micronutrients in a sulfate form was more effective in supplying S and micronutrients than FeSO4.
Studies were conducted to evaluate the effect of water application medium moisture deficit, water application rate, and intermittent application on water application efficiency {[(amount applied - amount leached)/amount applied] x 100} of spray stake-irrigated, container-grown plants. Pine bark-filled containers were irrigated to replace moisture deficits of 600, 1200, or 1800 ml; deficits were returned in single, continuous applications of 148, 220, or 270 ml·min-l. Efficiency was unaffected by application rate but decreased with increased medium moisture deficit. In the second experiment, container medium at a 600-ml deficit was irrigated with 400 or 600 ml (6570 and 100% water replacement, respectively); deficits were returned in a single, continuous application or in intermittent 100-ml applications with 30-min intervals between irrigations. Application efficiency was greater with intermittent irrigation (95% and 84% for 400- and 600-ml replacement, respectively) than with continuous irrigation (84% and 67% for 400- and 600-ml replacement, respectively). In the third experiment, pine bark was irrigated with 600 ml water (100% replacement) in 50-, 100-, or 150-ml aliquots with 20, 40, or 60 min between applications in a factorial design. Efficiency increased with decreasing application volume and increasing time between applications. Highest efficiency (86%) was achieved with an irrigation regimen of 50-ml applications with at least 40 min between applications, compared to 62% for the control treatment (a single, continuous application of 600 ml). Our results suggest that growers using spray stakes would waste less water by applying water intermittently rather than continuously.
In the spring of 2001 and 2002, different combinations of media (coarse perlite, medium perlite, and pine bark) and containers (polyethylene bags and plastic pots) were used for hydroponic production of `Galia' muskmelons (Cucumis melo L.) to determine their effect on fruit yield and quality, and their influence on costs of production. Marketable yields obtained for `Gal-152' in the spring 2001 and 2002 were 25.5 kg·m–2 and 39.0 kg·m–2 respectively. When data were combined for 2001 and 2002, fruit yield and fruit quality were unaffected by any combination of media and container. Average soluble solids content was generally greater than 10° Brix. It was determined that the use of pine bark media and plastic pots instead of perlite and bags would save $18,200 per year (two crops)—a feasible option for reducing costs of producing `Galia' muskmelons in greenhouses using soilless culture without loss of yield and fruit quality.
substrate air space. Substrate container capacity ranged from 51.8% to 66.6% (2008 experiment) and 53.9% to 60.5% (2009 experiment). Table 2. Physical properties of pine bark and whole pine tree substrates in a 2008 cutting propagation experiment. z Table 3
Substrates of container-grown plants are commonly preplant amended with sulfated micronutrients to supply micronutrients. However, the cause for the increased growth may be due to micronutrient addition or other factors such as S addition or substrate acidification. Container-grown pin oak (Quercus palustris Müench) and japanese maple (Acer palmatum Thunb.) seedlings were grown in a 100% pine bark substrate and amended (or not) with one of the following treatments: control (no amendment), Micromax, K2SO4, H2SO4, HCl, chelated micronutrients, elemental S, or CaSO4. After 11 weeks, dry weights of plants in all treatments supplying S were higher than plants receiving no S. Dry weights of plants in all experiments receiving the chelate treatment were not higher than dry weights for control plants. These data indicate that S, not micronutrient application, is a primary cause of increased growth from the addition of sulfated micronutrients. However, it was demonstrated that there are conditions such as higher substrate solution pH (4.1 vs. 5.4), where Micromax may prove advantageous over sulfur alone since it would supply micronutrients as well as S.
preparation. On 17 Mar. 2015, ≈2.5 m 3 of stabilized (aged between 4 and 6 months) loblolly pine bark screened through a 12.6-mm screen was attained from a commercial nursery substrate company (Pacific Organics, Henderson, NC). The bark was further separated
Abstract
Composted hardwood bark and aged pine bark were combined to produce two media with different particle size fractions. Media were combined with 3.8-, 5.7-, and 11.4-liter containers to produce six air and water capacities. Rooted cuttings of Ilex × ‘Nellie R. Stevens’ Van Lennep holly, × Cupressocyparis leylandii Jacks and Dall. ‘Ηaggerston Grey’ leyland cypress and Rhododendron × sp. ‘Sunglow’ azalea were potted in the resulting media–container combinations to determine the effects of particle size distribution, moisture and air content, and volume of containers on plant growth. Manipulating the particle size decreased the water held by ≈9%, but increased air space by ≈8% between the control and the coarse medium. The control medium yielded greatest top dry weight for all three species. Root dry weight and root ball volume were similar in coarse and control medium. Plant growth also was related to container size. A 2-fold increase in top dry weight occurred as container volume of the medium increased from 3.8 to 11.4 liters. Increasing container water content had a significant effect on top dry weight of all three species. Aeration was not as limiting to root growth as water content was to top growth.
materials; Fafard, Inc., Apopka, Fla., for providing sphagnum peat and pine bark used in this study, and Robert J. Black, Gladis Zinati, and Kelly Everitt for their critical reading of this manuscript. This research was supported in part by the Center for