Progress 07/01/02 to 06/30/07
Outputs
OUTPUTS: We characterized runoff water quality and quantity at a 9.31 acre constructed wetland in Cairo, GA at a commercial nursery that produces landscape plants. Over four years (2003-2006) of monthly sampling we determined the following: i. Deep, surface-flow vegetated constructed wetlands are effective for nitrogen removal. ii. Nitrogen loading and removal are linearly related; meaning that for every unit of nitrogen loaded a unit of nitrogen is transformed, assimilated, and/or removed. iii. The three-day hydraulic retention time of the first wetland cell provided the majority of the remediation efficiency, the second cell further polished wetland effluent. iv. Phosphorus sequestration is variable and on an annual basis phosphorus is exported by internal wetland cycling processes. Over three spring seasons with daily sampling, we determined the following: i. Nutrient loading into wetland increased with nursery fertilization and decay of plant material in wetland resulted in
higher nutrient concentrations, but the wetlands were able to remediate the nitrogen load even when environmental conditions were suboptimal. ii. Nitrogen remediation was influenced by water temperature, sulfur concentration, and NPOC. iii. Phosphorus remediation highly variable and only correlated with commencement of active plant growth. Changes in nutrient concentration in runoff water during storm events were correlated with rainfall hydrographs using samples collected during rain events using installed auto-samplers and monitoring equipment. We conducted a dissolved organic carbon addition study for increasing wetland nitrogen removal efficiency. Additional organic carbon was unnecessary in summer; adequate organic carbon was already present via growth and decay of plant material. No additional benefit was apparent. We evaluated of 19 aquatic garden plant species for nutrient uptake capacity and potential for use in the landscape or nursery production. Louisiana iris Full Eclipse
exhibited the highest N recovery rate. Canna Bengal Tiger, Canna Yellow King Humbert, Iris Full Eclipse, Peltandra virginica, Phyla lanceolata, and Pontaderia cordata Singapore Pink all exhibited similar P recovery rates. Thalia geniculata rheumoides and Oenenathe javanica Flamingo exhibited the highest nitrogen and phosphorus recovery rates, and can be utilized both near inflow and outflow of constructed wetland systems because of their high N and P assimilation capacities and recovery rates. Canna cultivars would best be utilized near inflow end of constructed wetland systems because they assimilate high N and P concentrations when adequate nutrients are present. Pontederia cordata Singapore Pink, Iris, and Peltandra virginica can be placed at the discharge end of constructed wetlands to "polish" the effluent because they have highly efficient N and P recovery rates.
PARTICIPANTS: Steve Klaine - Clemson University Environmental Toxicology Sarah White - Clemson University Environmental Toxicology Graduate Student Milton Taylor - Clemson University Environmental Toxicology Robert Polomski - Clemson University Horticulture Jerry Lee - Wrights Nursery - Monrovia Growers Cairo GA
TARGET AUDIENCES: Landscape plant producing nurseries and professionals that work with nurseries to improve water quality and use. Our efforts to reach the target offices included industry presentations, publications and extension publication. We also presented our research results at scientific meetings and published referred articles.
Impacts
These findings were reported at industry meetings (Southern Nursery Association, South Carolina Nursery Annual meeting, Southern Region Propagators Meeting, and Ohio Floral Short course) as well at professional and scientific meetings. Our research team including researchers from North Carolina State University, USDA-ARS scientist from Ft. Pierce FL and University of Florida scientist met annually and reviewed overall goals and results. An extension publication was developed and will be distributed by web based technology. The commercial nursery has expanded their constructed wetland programs and used our results in the design and construction of an additional 10 acres of treatment wetlands. A floating mat of vegetation is being evaluated based on the plants that we screen for phosphorus and nitrogen uptake.
Publications
- Polomski, R. F., M. D. Taylor, D. G. Bielenberg, W. C. Bridges. S. J. Klaine, and T. Whitwell, 2007, Nutrient recovery by seven aquatic garden plants in a laboratory-scale subsurface constructed wetland. HortScience 42:1674-1680.
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Progress 01/01/06 to 12/31/06
Outputs
Commercial nurseries use large amounts of water and nutrients to produce container-grown plants. The large volume of runoff containing nitrogen and phosphorus that leaves nurseries can contaminate surface and groundwater. We investigated the possibility of using commercially available aquatic garden plants in subsurface constructed wetlands by assessing their capacity to remove nutrients in a laboratory scale, gravel-based system. Seven popular aquatic garden plants received nitrogen and phosphorus from Hoagland's nutrient solution every two days for eight weeks. Plant biomass, nutrient recovery, and tissue nutrient contents and concentrations were measured. Whole plant dry weight was positively correlated with N and P supplied. Highest N recovery rates were exhibited by Iris Full Eclipse, Canna Bengal Tiger, C. Yellow King Humbert, Colocasia antiquorum Illustri, Peltandra virginica, and Pontederia cordata Singapore Pink. The P recovery rates were similar for the
cannas, C. antiquorum Illustris, I. Full Eclipse, Pe. virginica, and Po. cordata Singapore Pink. The potential exists for creating a sustainable nursery and greenhouse production system that incorporates a subsurface constructed wetland planted with marketable horticultural crops that provide remediation and revenue.
Impacts
Besides commercial floriculture and nursery production, these attractive species have the potential to be used in retention ponds and rain gardens to capture and filter runoff in commercial and residential landscapes and golf courses. Of growing international interest are "natural swimming pools" that rely on potted, gravel-grown aquatic plants to maintain water quality by absorbing nutrients and supporting microbial growth.
Publications
- Taylor, M. D., S. A. White, S. L. Chandler, S. J. Klaine, T. Whitwell. 2006. Nutrient management of nursery runoff using constructed wetlands. HortTechnology 16: 610-614
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Progress 01/01/05 to 12/31/05
Outputs
Nursery and greenhouse production is based on the application of substantial quantities of water and nutrients to achieve profitable plant growth and quality. As water quality criteria are strengthened locally or nationally, horticultural enterprises will have to meet stricter limits on nutrients in discharge water and there will be dramatic impacts on how they irrigate and handle the resultant runoff. This study collected monitoring data for 38 months on the efficacy of an established vegetated surface-flow constructed wetland nutrient remediation system to evaluate its value for nutrient management of nursery runoff water. Maximum oxidized nitrogen inputs occurred during the spring fertilization period of March through Mayand minimum inputs occurred during winter plant dormancy between December and February. Nitrogen remediation efficiency was very high for March through November sampling dates but declined between December and February when mean wetland water
temperature was cold. Orthophosphate phosphorus concentrations in nursery runoff showed no dramatic changes over months, seasons, or years. Mean wetland influent orthophosphate concentration was variable for all months sampled. Phosphorus remediation efficiency varied widely and there was no correlation with water temperature. This surface-flow constructed wetland was highly efficient at removing nitrogen from nursery runoff from but failed to consistently lower orthophosphate levels in runoff. This type of constructed wetland is suitable for removing oxidized nitrogen forms from nursery runoff and, depending on size, is capable of handling the large volumes of runoff generated by medium to large nursery and greenhouse growers.
Impacts
Passive economical remediation systems will be adopted by the nursery/greenhouse industry to remove nritrates, phosphates and pesticides from runoff water. These systems will reduce the potential for water pollution problems. Water quality and quantity problems are recognized by the industry as a future limitation to profitable and sustainable productions systems. This research provides needed information as to the viability of constructed wetlands as a remediation system.
Publications
- Taylor, M. L., S. A. White, S. J. Klaine and T. Whitwell. 2005. Monitoring Nutreint Mitigation at a Container Nursery Wetland:3 -year study. HortScience 40:1049.
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Progress 01/01/04 to 12/31/04
Outputs
Container-grown plants require large amounts of water and nutrients during their production cycle. This results in substantial runoff that is contaminated with nitrogen and phosphorus. At our study site, nutrients were delivered through incorporation in the potting media as timed-release prills and through liquid feeding by injection into irrigation water. Mitigation of nutrients in runoff water was dealt with proactively by the container nursery with construction of 3.77 ha of planted wetlands to receive runoff from a 48.6 ha drainage basin and excess water diverted from adjacent watersheds. Water flowed though drains between wetland cells and eventually into stilling ponds before it was allowed to exit the property. Water flow through the wetlands ranged from 1.1 to 3.1 M L/D over the period. Three years of monitoring data indicates some seasonal differences in nitrogen removal efficiencies. Nitrogen removal between March and November averaged >95% while removal
during winter (December through February) averaged >72%. Nitrogen (as nitrate) varied from 4.28 ppm to <0.01 ppm in wetland discharge, well below drinking water quality standards but occasionally above levels that may cause downstream eutrophication. Orthophosphate phosphorus removal was highly variable with greatest removal occurring during late spring, late fall, and winter. There was a significant net export of phosphorus during some summer months for years 2 and 3. Phosphorus levels in wetland discharge ranged between 0.84 and 2.75 ppm. While there is currently no legal water quality standard for phosphorus, these levels were above the generally accepted level for preventing downstream eutrophication.
Impacts
Passive economical remediation systems will be adopted by the nursery/greenhouse industry to remove nritrates, phosphates and pesticides from runoff water. These systems will reduce the potential for water pollution problems.
Publications
- MD Taylor, SJ Klaine, and T Whitwell. 2004.N and P Discharge During Spring Regrowth from Constructed Wetlands in a Commercial Nursery. SNA Research Conference Proceedings. 49:533to534.
- Polomski, R. F., M. D. Taylor, S. J. Klaine, T. Whitwell, and W. C. Bridges. 2004.Screening landscape plants for their ability to accumulate nitrogen and phosphorus. Southern Nursery Association Research Conference Proceedings 49: 20 to 22.
- Jones, D. A., R. F. Polomski, M. D. Taylor, S. J. Klaine, T. Whitwell, and W. C. Bridges. 2004. Comparison of Canna and Willow for Nitrogen and Phosphorus Uptake andAccumulation. Southern Nursery Association Research ConferenceProceedings, 49: 117 to 119.
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Progress 01/01/03 to 12/31/03
Outputs
Container-grown plants from commercial nurseries require large amounts of water and nutrients during their production cycle resulting in substantial runoff contaminated with nitrogen and phosphorus. Thus, mitigation of offsite movement of nutrients in runoff is a serious concern for the nursery and greenhouse industry. Wight Nurseries of Monrovia Growers, Cairo, GA has installed 3.77 ha of planted wetlands to receive direct runoff in excess of recapture needs from a 48.6 ha drainage basin and excess water diverted from adjacent watersheds. Water flows though trench drains between wetland cells and eventually into stilling ponds before it is allowed to exit the property. Water flow through the wetlands ranges from 1.6 million to 2.2 million liters per day. Two years of monitoring data indicates strong seasonal differences in nitrate and nitrite nitrogen removal efficiencies. Nitrogen removal between April and November averaged 93.3% while removal during winter months
averaged 44.1%. Nitrite was not found in wetland discharge water samples. Nitrogen as nitrate in discharge water varied from 0.05 ppm to 4.3 ppm, well below drinking water quality standards, and was below 0.6 ppm between June and November except in September during construction activity. Orthophosphate phosphorus removal was highly variable with highest removal occurring during late spring, averaging 33.6%, and some removal occurring during early fall, averaging 13.8%. However, there was a net export of phosphorus from the wetlands during winter months and during periods of low vegetative growth. Phosphorus levels ranged between 0.9 and 1.9 ppm. While there is currently no legal water quality standard, these levels are above the generally accepted level of 0.01 ppm for preventing downstream eutrophication.
Impacts
Passive economical remediation systems will be adopted by the nursery/greenhouse industry to remove nritrates, phosphates and pesticides from runoff water. These systems will reduce the potential for water pollution problems.
Publications
- Whitwell, T., M. Taylor, and S.Klaine, 2003. Constructed wetland system for mitigationof nutrient contamints in offsite drainage from a comercial nursery. HortScience 38:672.
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Progress 01/01/02 to 12/31/02
Outputs
Sprayable and granular formulations of isoxaben and trifluralin were applied to container plant nursery beds to determine formulation effects on herbicide runoff and weed control. Herbicide applications were followed by 0.8 cm of irrigation delivered over 60 min, and runoff water samples were collected on the day of application (DOA). Highest concentrations of isoxaben and trifluralin detected in runoff water were 0.50 and 0.15 mg ml-1, respectively. Total isoxaben amounts in runoff water were greater from the granular formulation than the sprayable formulation, but no differences due to formulation were detected for trifluralin. The total amount of isoxaben recovered was 9.1% of applied from the granular formulation and 7.3% of applied from the spray formulation. Total amounts of trifluralin found were similar among formulations (0.5% of applied). Weed control was similarly effective for both formulations in both years.
Impacts
The impact of this research is to reduce herbicide movement off site in nursery runoff water with better management of irrigation and herbicide selection.
Publications
- Briggs, J. A., T. Whitwell, R. T. Fernandez, and M. B. Riley. 2002. Formulation effects isoxaben and trifluralin in runoff water from container nurseries. Weed Science 50:536-541.
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