Browsing by Author "Owen, James S. Jr."

Now showing 1 - 11 of 11
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    Applications of High-Resolution Imaging for Open Field Container Nursery Counting
    She, Ying; Ehsani, Reza; Robbins, James; Nahún Leiva, Josué; Owen, James S. Jr. (MDPI, 2018-12-12)
    Frequent inventory data of container nurseries is needed by growers to ensure proper management and marketing strategies. In this paper, inventory data are estimated from aerial images. Since there are thousands of nursery species, it is difficult to find a generic classification algorithm for all cases. In this paper, the development of classification methods was confined to three representative categories: green foliage, yellow foliage, and flowering plants. Vegetation index thresholding and the support vector machine (SVM) were used for classification. Classification accuracies greater than 97% were obtained for each case. Based on the classification results, an algorithm based on canopy area mapping was built for counting. The effects of flight altitude, container spacing, and ground cover type were evaluated. Results showed that container spacing and interaction of container spacing with ground cover type have a significant effect on counting accuracy. To mimic the practical shipping and moving process, incomplete blocks with different voids were created. Results showed that the more plants removed from the block, the higher the accuracy. The developed algorithm was tested on irregular- or regular-shaped plants and plants with and without flowers to test the stability of the algorithm, and accuracies greater than 94% were obtained.
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    Cold Hardiness of Grevillea in Western Oregon
    Bell, Neil; Stoven, Heather; Owen, James S. Jr.; Altland, James E. (2020-02)
    A cold hardiness evaluation of 57 cultivars and species of grevillea (Grevillea) was conducted from 2011 to 2014 in Aurora, OR, to assess landscape suitability in the Pacific Northwest United States. Plants were established using irrigation in 2011, but they received no supplemental water, mineral nutrients, or pruning from 2012 to 2014. Plants were evaluated for injury in Mar. 2012 and Jan. 2014 after winter cold events with minimum temperatures of -4 and -13 degrees C, respectively. Damage, at least on some level, occurred on most selections following their first winter after planting in 2011. During Winter 2013, further damage to, or death of, 33 grevillea cultivars or species occurred. The grevillea that exhibited the least cold damage and the most promise for landscape use and further evaluation in the Pacific Northwest United States were 'Poorinda Elegance' hybrid grevillea, southern grevillea (G. australis), cultivars of juniper-leaf grevillea (G. juniperina) including Lava Cascade and Molonglo, and oval-leaf grevillea (G. miqueliana), all of which exhibited minor foliage damage.
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    Data on floating treatment wetland aided nutrient removal from agricultural runoff using two wetland species
    Spangler, Jonathan T.; Sample, David J.; Fox, Laurie J.; Owen, James S. Jr.; White, Sarah A. (Elsevier, 2018-12-15)
    The data presented in this article are related to the research article entitled “Floating treatment wetland aided nutrient removal from agricultural runoff using two wetland species” (Spangler et al., 2018). This Data in Brief article provides data on concentrations of common ions, macro- and micro-nutrients and metals every other week during a floating treatment wetland (FTW) mesocosm experiment, and macro- and micro-nutrient contents in cumulative plant tissues, data on continuously monitored water temperature, and nitrogen and phosphorus removal curves assessed every other week. The full data set is made available to enable critical or extended analysis of the research.
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    Dolomite and Micronutrient Fertilizer Affect Phosphorus Fate in Pine Bark Substrate used for Containerized Nursery Crop Production
    Shreckhise, Jacob H.; Owen, James S. Jr.; Eick, Matthew J.; Niemiera, Alexander X.; Altland, James E.; White, Sarah A. (2019-09)
    Dolomite and a micronutrient fertilizer are routinely incorporated into a pine bark-based soilless substrate when producing containerized nursery crops, yet the effect of these amendments on phosphorus (P) is not well understood. The objective of this research was to determine the effect of dolomite and micronutrient fertilizer amendments on P partitioning among four P fractions (i.e., orthophosphate-P EOM non-orthophosphate dissolved P [NODP], total dissolved P [TDP], and particulate P (PPJ) and to model potential P species in leachate of pine bark substrate. Amendment treatments incorporated into bark at experiment initiation included (1) a control (no fertilizer, dolomite, or micronutrient fertilizer), (2) controlled-release fertilizer (CRF), (3) CRF and dolomite, (4) CRF and micronutrient fertilizer, or (5) CRF, dolomite, and micronutrient fertilizer. Phosphorus fractions in leachate of irrigated pine bark columns were determined at eight sampling times over 48 days. Amending pine bark with dolomite and micronutrient fertilizer reduced leachate OP concentrations by 70% when averaged across sampling dates primarily due to retention of OP in the substrate by dolomite. The NODP fraction was unaffected by amendments, and the response of TDP was similar to that of OP. Particulate P was present throughout the study and was strongly correlated particulate Fe and DOC concentrations. Visual MINTEQ indicated MnHPO4 and Ca-5(PO4)(3)(OH) were consistently saturated with respect to their solid phase in treatments containing CRF. Results of this study suggest amending pine bark with dolomite and micronutrients is a best management practice for reducing P leaching from containerized nurseries.
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    Dolomite and Micronutrient Fertilizer Affect Phosphorus Fate When Growing Crape Myrtle in Pine Bark
    Shreckhise, Jacob H.; Owen, James S. Jr.; Eick, Matthew J.; Niemiera, Alexander X.; Altland, James E.; Jackson, Brian E. (American Society for Horticultural Science, 2020-05-07)
    Soilless substrates are routinely amended with dolomite and sulfate-based micronutrients to improve fertility, but the effect of these amendments on phosphorous (P) in substrate pore-water during containerized crop production is poorly understood. The objectives of this research were as follows: compare the effects of dolomite and sulfate-based micronutrient amendments on total P (TP), total dissolved P (TDP), orthophosphate P (OP), and particulate P (PP; TP − TDP) concentrations in pour-through extracts; to model saturated solid phases in substrate pore-water using Visual MINTEQ; and to assess the effects of dolomite and micronutrient amendments on growth and subsequent P uptake efficiency (PUE) of Lagerstroemia L. ‘Natchez’ (crape myrtle) potted in pine bark. Containerized crape myrtle were grown in a greenhouse for 93 days in a 100% pine bark substrate containing a polymer-coated 19N–2.6P–10.8K controlled-release fertilizer (CRF) and one of four substrate amendment treatments: no dolomite or micronutrients (control), 2.97 kg·m−3 dolomite (FL); 0.89 kg·m−3 micronutrients (FM); or both dolomite and micronutrients (FLM). Pour-through extracts were collected approximately weekly and fractioned to measure pore-water TP, TDP, and OP and to calculate PP. Particulate P concentrations in pour-through extracts were generally unaffected by amendments. Relative to the control, amending pine bark with FLM reduced water-extractable OP, TDP, and TP concentrations by ≈56%, had no effect on P uptake efficiency, and resulted in 34% higher total dry weight (TDW) of crape myrtle. The FM substrate had effects similar to those of FLM on plant TDW and PUE, and FM reduced pore-water OP, TDP, and TP concentrations by 32% to 36% compared with the control. Crape myrtle grown in FL had 28% lower TDW but pour-through OP, TDP, and TP concentrations were similar to those of the control. Chemical conditions in FLM were favorable for precipitation of manganese hydrogen phosphate (MnHPO4), which may have contributed to lower water-extractable P concentrations in this treatment. This research suggests that amending pine bark substrate with dolomite and a sulfate-based micronutrient fertilizer should be considered a best management practice for nursery crop production.
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    Evaluation of commercial floating treatment wetland technologies for nutrient remediation of stormwater
    Lynch, Jeanette; Fox, Laurie J.; Owen, James S. Jr.; Sample, David J. (Elsevier, 2013-12)
    Floating treatment wetlands (FTWs) are a relatively new water treatment practice that consists of emergent wetland plants planted on floating mats constructed of buoyant material. This study utilized batch-fed mesocosms, with a seven-day retention time, to investigate the total nitrogen (TN) and phosphorus (TP) remediation capability of two commercially available FTW technologies using runoff from a combined irrigation holding and stormwater retention pond. Nutrients in the pond water are attributed to runoff from nearby fertilized research plots upgradient. The FTW technologies included Beemats (Beemats LLC, New Smyrna Beach, FL, USA) and BioHaven® floating islands (Floating Island International, Inc. Shepard, MT, USA) planted with Juncus effusus (soft rush). Due to an increase in TN and TP in the initial phase of the experiment during the plant establishment phase (weeks 1–8), BioHaven®nutrient removal was lower over the entire experimental period than the Beemat treatment. Differences between the two treatments, such as mat material or substrate materials and/or additives may account for this difference. The BioHaven® FTW removed 25% and 4%, while the Beemat removed 40% and 48% of the TN and TP, respectively expressed in terms of net removal over the entire study. During the plant growth season (weeks 9–18 of the study), the two technologies showed similar nutrient removal rates: for TN:0.026 ± 0.0032 and 0.025 ± 0.0018, and for TP:0.0074 ± 0.00049 and 0.0076 ± 0.00065 g/m2/day for Beemat and Biohaven®, respectively. A control treatment, meant to reflect nutrient removal within the pond without the presence of plants, yielded 28% and 31% removal of TN and TP, respectively. Thus, the Beemat mat yielded a significant positive net removal of TN and TP. The BioHaven® biomass was significantly greater than the Beemat treatment. Both treatments showed greater biomass accumulation in shoots rather than in roots. Plant nutrient content was similar between the two treatments.
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    Growth response of Hydrangea macrophylla and Ilex crenata cultivars to low-phosphorus controlled-release fertilizers
    Shreckhise, Jacob H.; Owen, James S. Jr.; Niemiera, Alexander X. (2019-02-27)
    In containerized nursery-crop production, conventional phosphorus (P) fertilization amounts are reported to be in excess of plant needs which has resulted in poor P use efficiency (PUE) and subsequent P leaching from containers. Phosphorus leaching can be reduced and PUE improved without affecting plant growth by reducing P fertilization. The objective of this study was to identify the lowest controlled-release fertilizer (CRF)-P content and subsequent pour-through-extracted substrate pore-water P (PWP) concentration that produces maximal shoot growth of two common container-grown nursery crop species, Hydrangea macrophylla 'PIIHM-II' (hydrangea) and Ilex crenata 'Helleri' (holly), in a pine bark substrate. Hydrangea and holly liners were potted into 3.8-L containers containing a pine bark substrate and grown simultaneously in two different Virginia ecoregions, Middle Atlantic Coastal Plain (MACP) and Ridge and Valley (RV). Plants were fertilized with one of five CRF formulations, each containing equal nitrogen (N) and potassium (K) and 0.4%, 0.9%, 1.3%, 1.7% or 2.6% (control) P to supply containers with 0.1, 0.2, 0.3, 0.4 or 0.6 g P, respectively. In both ecoregions, hydrangea shoot dry weight (SDW) and growth index [i.e., (widest width + perpendicular width + height) divided by 3, GI] values were maximal in plants fertilized with 0.3 to 0.4 g P or the control. The lowest CRF-P rate needed for maximal SDW and GI of holly was 0.2 g P at the RV site and 0.4 g P at the MACP site. Mean PWP concentrations that corresponded with highest SDW were as low as 0.8 and 1.2 mg L-1 for hydrangea and holly, respectively. Results from this research suggest hydrangea requires approximately half the P rate supplied by recommended rates of conventional CRFs. Since the growth response of holly to CRF-P rate at the MACP site was inconsistent with results observed at the RV site and findings in scientific literature, further research is needed to determine the minimum required CRF-P rate for this taxon.
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    Influence of Lime Type and Rate on Pine Bark Substrate pH
    Jarrett, Richard L.; Owen, James S. Jr. (Virginia Tech, 2017-12-25)
    Pine bark substrate in the southeastern U.S. is the substrate of choice for ornamental plant producers. The low pH of the unbuffered substrate needs to be adjusted with a lime material in order to promote proper nutrient uptake and ensure general plant health to avoid abiotic disorders. The research and data collection from this study evaluated the long-term effect of four lime materials and five rates on the pH of a pine bark substrate that was planted with rooted holly cuttings over nine-months. We found that pH is raised by lime material and rate over time, with >4.5 kg•m-3 needed to maintain an optimal pH for ornamental plant growth. Our data along with past research on the subject will benefit producers in using the proper lime material and rate for optimal plant health and to prevent abiotic disorders during crop production.
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    Physical and Hydraulic Properties of Commercial Pine-bark Substrate Products Used in Production of Containerized Crops
    Altland, James E.; Owen, James S. Jr.; Jackson, Brian E.; Fields, Jeb S. (2018-12)
    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 approximate to 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.
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    Removal Efficacy of Nursery Tail-Water Nitrogen and Phosphorus using Ferric aided Zeolite Sieves with or without Bioreactors
    Birnbaum, Anna P. (Virginia Tech, 2018-12-03)
    Nitrogen (N) and Phosphorus (P) runoff from containerized nurseries contributes to eutrophication in impaired US waterways. Best management practices (BMPs) have been in development for much of the agricultural sector to help combat this problem. Unfortunately, the only approved BMP for the containerized nursery industry is >95% runoff containment of >19 mm rainfall through the use of retention ponds. This study aimed to evaluate the effectiveness of ferric aided zeolite sieves with or without bioreactors as a potential BMP for N and P removal of containerized nursery production tail-water. A continuous flow of nursery tail-water was pumped through nine treatment trains for twelve weeks along with a 4.5 mg·L-1 injection of iron using ferric sulfate. Aqueous nutrient samples were collected weekly and electrochemical properties were measured in situ. The ferric aided zeolite sieve without woodchip bioreactor achieved an average P removal efficiency of 29.8% with no effect on N removal. Woodchip bioreactors preceding zeolite had a net increase of P (-3.3%), but was effective for N removal with an average rate of 14.3%. Higher N removal was expected by the denitrification bioreactors; however, retention times, presumably >24hrs, and high sulfur concentrations led to dissimilatory nitrate reduction to ammonium (DNRA) as opposed to the desired denitrification which results in the product of innocuous dinitrogen gas. Results indicate that ferric aided zeolite+woodchip bioreactor treatment trains may be effective for N and P reduction in nursery tail-water if designed properly to avoid excessive retention times in the denitrification bioreactors.
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    Seven Steps to Sustainable Landscaping Virginia Tech
    Orr, William (Virginia Tech, 2014-12)
    Presentation and educational resources prepared for Virginia Cooperative Extension