Producing Native – Ornamental Wetland Plants in Constructed Wetlands Designed to Reduce Pollution from Agricultural Sources

1998 Annual Report for LNE98-100

Project Type: Research and Education
Funds awarded in 1998: $72,840.00
Projected End Date: 12/31/2001
Matching Non-Federal Funds: $60,663.00
Region: Northeast
State: Rhode Island
Project Leader:
Brian Maynard
University of Rhode Island

Producing Native – Ornamental Wetland Plants in Constructed Wetlands Designed to Reduce Pollution from Agricultural Sources


The purpose of this project is to provide farmers with an economic incentive for the treatment of non-point source pollution by allowing them to grow and sell wetland plants produced in a constructed wetland designed to treat agricultural runoff. At a participant’s farm, a demonstration wetland was constructed that intercepts and treats nursery runoff. Influent and effluent water samples were collected and compared for nitrogen and phosphorus reduction.

1. Demonstrate an economical solution to treating nursery runoff by growing, harvesting, and selling native and ornamental wetland plants produced in a constructed wetland treating runoff from a commercial nursery.

2. Evaluate the economic impact of converting nursery production space into a treatment wetland production space.

3. Research the possibility of enclosing treatment wetlands in passively heated polyhouses to facilitate year around treatment of agricultural runoff.

4. Distribute the results of this study to farmers and other agricultural businesses or professionals interested in treating runoff with created wetlands via an extension/outreach program consisting of seminars, workshops, field trips, slide shows and fact sheets.

Results to date
Busloads of horticultural professionals were able to visit the site during an annual nursery meeting. They participated in a demonstration detailing the function of this wetland system, followed by a short question and answer period. Next year’s demonstration will concentrate on the production and care of wetland plants, as well as identifying buyers and sellers of wetland plant material. It will be explained how partial harvests not only remove nutrients from the wetland, but are necessary for stock plant expansion. After the demonstration is over participants will be able to purchase wetland plants for their garden centers, mitigation projects and landscapes.
A series of wetland mesocosms were built at the East Farm Agriculture Experimental Station of the University of Rhode Island. These wetlands have both a research and a demonstration component. Agricultural professionals have visited the facility where treatment wetlands have been incorporated under passively heated polyhouses (unheated polyethylene covered greenhouses). These wetlands were especially designed to remove pollutants during the winter. In these inexpensive structures water is passively heated during the day and at night the heat is re-radiated back. We are in the process of quantifying the amount of nutrient removal from polyhouse wetlands verses outdoor wetlands. We will publish our findings in refereed journals and popular media. This data should be of interest to farmers and agricultural businesses that generate waste water year around, such as barnyards and milking parlors.
Our project is proceeding successfully and according to schedule. We have not made any changes in focus from our original project proposal. We are currently collecting pertinent reference materials, and designing fact sheets describing the design and construction of wetlands for the purpose of treating agricultural runoff and describing the production of wetland plants. These materials will be collected into an accessible library and will be made available next spring. Through slide shows and open houses we will encourage farmers to address water quality issues in collaboration with other farmers, agricultural and environmental agency personnel, and university and extension staff.

Reported December 1999.


Dixon Hoogendoorn

Hoogendoorn Nurseries, Inc
William Johnson

Research Assoc. IV
Dept. of Plant Sciences, URI
Jose Amador

Dept. of Natural Resources, URI
Thomas Holt

Graduate Research Assistant III
University of Rhode Island