Virginia Agricultural Experiment Station

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https://hdl.handle.net/10919/24235
The Virginia Agricultural Experiment Station conducts research on food and fiber systems, their impact on the environment, and their relation to the future needs of Virginia, the nation, and the world.

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Browsing Virginia Agricultural Experiment Station by Department "Hampton Roads AREC"

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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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    On-farm Evaluation of Strawberry Cultivars in Coastal Virginia
    Flanagan, Roy; Samtani, Jayesh B.; Manchester, Mikel Ann; Romelczyk, Stephanie; Johnson, Charles S.; Lawrence, Watson; Pattison, Jeremy (American Society for Horticultural Science, 2020-12)
    Strawberries (Fragaria ananassa) are one of the major high-value crops in North America. There is increasing interest in commercial strawberry production for local markets in Virginia and surrounding states, but information on the performance of newer cultivars is extremely limited. We tested 10 commercially available June-bearing cultivars [Benicia, Camarosa, Camino Real, Chandler, Strawberry Festival, Flavorfest, FL Radiance, Treasure, Sweet Charlie, and WinterstarTM (FL 05-107)] and two day-neutral cultivars (Albion and San Andreas) for their spring and summer fruiting capacity in Virginia production systems in a randomized, replicated study, at three on-farm locations. Data were collected on vegetative growth, yield performance, fruit quality, sweetness, and fruit diameter. Cultivars with the highest total yields averaged across all three locations were Benicia, Camino Real, Chandler, and Camarosa. ‘Camino Real’ had the highest marketable yield at all three locations, not significantly different from ‘Chandler’, and ‘Benicia’ and ‘Camarosa’ had the highest marketable yield at two of the three locations. ‘Flavorfest’ and ‘Sweet Charlie’ had the highest total soluble solids concentration for the harvest season. Overall, for all locations, ‘Benicia’ and ‘Camino Real’ had the largest fruit diameter, and ‘Strawberry Festival’ had the smallest fruit diameter.
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    Systems Analysis of Coupled Natural and Human Processes in the Mekong River Basin
    Sridhar, Venkataramana; Ali, Syed Azhar; Sample, David J. (MDPI, 2021-09-12)
    The Mekong River Basin is one of the world’s major transboundary basins. The hydrology, agriculture, ecology, and other watershed functions are constantly changing as a result of a variety of human activities carried out inside and by neighboring countries including China, Myanmar, Thailand, Laos, Cambodia, and Vietnam in order to meet increased food and water demands for an increasing population. The Mekong River, which provides irrigation and fishing for a population of over 60 million people, also has an estimated 88,000 MW of untapped hydropower potential. The construction of dams for energy supply has a wide-ranging impact on downstream reservoir regions, resulting in unprecedented changes in hydrologic functions, the environment, and people’s livelihoods. We present a holistic view of how external stressors such as climate change and variability, land cover, and land-use change affect supply and demand. We present an integrated modeling framework for analyzing the supply–demand scenarios and tradeoffs between different sectors. Specifically, we evaluated the impacts of future climate on irrigation, hydropower, and other needs in the basin through a feedback loop. We focused on hydrologic extremes to evaluate their impacts on the reservoir operations during flood and low flow events. The inflow is projected to change by +13% to −50% in the future, while a 0.25% (15.24 billion m3) reduction is projected for the net irrigation water requirement (NIWR). A unit percentage increase in irrigation demand will reduce energy generation by 0.15%, but climate change has a beneficial impact on dam performance with a predicted increase in energy generation and supply to all sectors. Flood events will cause excessive stress on reservoir operation to handle up to six times more flow volumes; however, the low-flow events will marginally affect the system. While the flow and storage rule curves consider both supply and demand, changing human water use comes second to changing climate or other biophysical considerations. This paper emphasizes the importance of considering feedback between climate–water–human society in the systems modeling framework in order to meet societal and ecological challenges. The findings will provide information on the risks and tradeoffs that exist in the water, energy, and food sectors of the basin.