Nov 28

Use of Wetland Systems to Treat Nursery Runoff

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A constructed wetland

Constructed wetlands filter pollutants from nursery runoff. Growers can use this technology to protect surface waters from nutrient enrichment.

More than 56.6 million acres of land were irrigated in the United States in 2007, of which 56% was irrigated by sprinkler and microirrigation systems.1  We are developing treatment technologies to cleanse irrigation runoff either before reuse for irrigation or release into the environment.  By developing constructed wetland and vegetative buffer design technologies for use as an environmental best management practice, our team will provide growers with plant-based technology to remove sediment, nutrient, pathogen, and pesticide contaminants from water.

Through collaboration among plant scientists, plant pathologists, and environmental toxicologists, with commercial nursery and greenhouse growers in GA and SC, we are designing ecological treatment systems to cleanse water.  These treatment systems rely on natural processes to remove contaminants rather than chemical treatments.  Developing this technology will increase reuse of irrigation runoff (saving potable water resources for non-irrigation uses) and increase worker safety.  Close cooperation among researchers and commercial growers takes advantage of everyone’s expertise, ensuring progress towards implementation of the science into practice.

During the past three years, we have monitored the efficacy of two constructed wetlands to facilitate removal of nutrients and pathogen contaminants from runoff.  The wetlands reduced export of total nitrogen by 69%, phosphorus by 39%, and Phytophthora spp. (a pathogen) by 80%.  Over 630,000 gallons of water flow through these wetlands each day, and an average of 143 lbs. of nitrogen and 0.12 lbs. of phosphorus are removed from runoff on a daily basis.  Given that it takes only 0.02 ppm phosphorus to contribute to nutrient enrichment and potential impairment of surface waters2, optimizing best management practices to reduce nutrient export into surface waters is critical.  This technology to filter contaminants from runoff not only helps to protect our surface waters, but can also be applied to increase re-use of irrigation runoff to save potable water sources for other uses.