Enhancing the Maryland Nursery Industry's Ability to Improve Water Quality and Increase Profit

1. Project Name and Contact Information

Enhancing the Maryland Nursery Industry’s Ability to Improve
Water Quality and Increase Profit
FNE 04-517

Environmental Concern Inc.
Leslie Hunter-Cario
P.O. Box P
St. Michaels, MD 21663
410-745-9620
horticulture@wetland.org

2. Goals

The nursery facility at Environmental Concern Inc. (EC) is located in an environmentally sensitive area at the edge of San Domingo Creek, a tributary to the Chesapeake Bay. Nutrient pollution is a major contributor to the continuing decline of water quality throughout the country. Agriculture practices contribute to nutrient loading. To reduce their impact, the state has mandated that farming practices institute nutrient management programs. One component of Environmental Concern’s nutrient management plan is a nutrient management pond. Committed to the environment, Environmental Concern is always seeking ways to further reduce its ecological footprint. This project allowed us to investigate ways in which to increase the efficiency of the nutrient management pond. We proposed vegetating the entire surface area of the nursery’s nutrient management ponds to increase the amount of nutrients filtered out of the water, and improve the quality of possible surface runoff from the nursery.

Not only will the improved nutrient management ponds provide cleaner water, but they also have the potential to increase nursery revenue. The plants require maintenance and thinning to ensure efficient nutrient removal, therefore individual plants removed during the thinning process may then be sold. Also, seeds may be collected from plants in the pond in order to propagate new individual plants for sale.

EC will share the information gained with industry professionals and extension educators interested in duplicating this process. With over 500 nurseries operating in Maryland alone, the project has the potential to exact significant reductions in nutrient loadings associated with normal nursery practices. If this sustainable and innovative practice is adopted across the northeastern United States, all will reap the benefits of healthier waterways supporting a multitude of diverse native species.

3. Farm Profile

Environmental Concern Inc. (EC) is a public not-for-profit organization specializing in wetland horticulture, education, research, construction and restoration. EC’s nursery is structured for wholesale business, with a small percentage retail sales. Revenue generated from nursery sales supports EC’s education and research initiatives. More than one hundred herbaceous and woody wetland species are grown on the 13.6 acre facility. All species grown are native to the northeastern United States, and most can be considered locally native, originating from the Delmarva Peninsula. To help maintain genetic diversity, all plant species are grown from seed whenever possible and practicable.

EC’s nursery holds a current Nursery Inspection Certificate, renewed annually, certifying the plant material free of harmful insect and/or disease per inspection by the Maryland Department of Agriculture (MDA). The EC nursery also holds a current nutrient management plan. The plan was submitted as required by law to the MDA, and written by an independent nutrient management planner certified and licensed by the MDA. Based on the nutrient management and fertilization practices utilized, Environmental Concern’s nursery operations have been classified as a “low management risk.” Nutrient run-off is limited by the use of low rates of slow-release fertilizer and self-contained plant beds for water-loving species. Plant beds under overhead irrigation are controlled by timers, so they can be programmed cyclically to avoid over-watering and potential nutrient leaching.

4. Participants

EC personnel carried out most of the work related to the nutrient management project. EC Nursery Manager Leslie Hunter-Cario managed the overall project and outreach. Various EC employees were involved with floating mat assembly and structural improvements to the nutrient management ponds. Summer Intern Kelly Cottingham planted mats and collected data during the 2007 growing season.

Technical Advisor Shannon Potter Dill of the Maryland Cooperative Extension will include results of the project in the agency’s early 2008 newsletter. In 2004, she provided us with the opportunity to present the project at a Maryland Cooperative Extension Plant Clinic.

The Maryland Nursery and Landscape Association (MNLA) served as a partner/collaborator on the project. The MNLA assisted EC with its outreach plan by holding its Annual Field Day at EC, with a theme of nutrient management and use of native species. In early 2008, the MNLA will also publicize the nutrient management pond project through their website and their printed periodical, the “Free State Nursery and Landscape News.”

Dick Shuck of Maryland Aquatic Nurseries, Inc., also a project collaborator, suggested the switch to floating mats and provided insights towards their assembly and installation. He also facilitated a visit to the University of Maryland Center for Environmental Sciences where Dr. Andy Lazur is studying nutrient uptake with the mats as part of an aquaculture system.

5. Project Activities

To prepare for planting, it was necessary to remove unwanted vegetation from the pond. During the 2005 growing season, all vegetation was removed from within the deepest pond by excavator and shovel. An aquatic approved herbicide was applied to weedy vegetation surrounding the deepest and medium-depth ponds. Within the medium-depth pond, the vegetation had been almost entirely eaten by a family of muskrats. Extensive tunneling by the muskrats and the resulting collapse of some adjacent areas prompted the need for muskrat relocation. Four muskrats were trapped and relocated outside of the county. Additional structural reinforcements to the pond perimeter were necessary.

A change to the experimental design was approved in October of 2005. We learned of a low-maintenance method of installing and holding plants in the pond, which was more practical than the original design involving fixed wooden boxes. The new method utilizes floating mats which can be linked together and reeled in for easy access to plant material, as needed. Maryland Aquatic Nurseries distributes several types of polyethylene foam floating mats, two of which seemed appropriate for our needs. The first model holds a section of coir blanket in which plants can be directly planted. The second model has die-cut holes, in which potted plants can be suspended. As with the wooden boxes, we were able to experiment with both bare root and container-grown herbaceous plants.

Materials to construct the rafts were acquired, and assembly took place in early 2006. In March of that year, stairs were constructed to facilitate access to the pond for floating the mats and testing the water. During the 2006 growing season, we planted and floated both types of mats, and secured them with rope to the banks of the pond. Based on observations at the University of Maryland Center for Environmental Sciences,
and several months of evaluation at EC, we determined that the second model of mat was more cost-effective for our purposes and easier to handle.

During the 2007 growing season, ten species of wetland plants were selected to be planted in the mats. Selection was based on the plants’ ability to sustain saturated conditions. Additional plants were chosen for salinity tolerance. A total of sixteen floating pot mats were planted. Twelve mats were floated in the deepest nutrient pond and two in the moderate depth pond. Additionally, two mats were anchored from EC’s dock to see if the plants could assist with nutrient uptake in San Domingo Creek (brackish water).

Herbaceous plugs were planted in standard quart pots containing a pine bark and sand media, with no fertilizer added. Two sets of plants were measured for height prior to being placed in mats and enclosed with wire mesh to prevent possible herbivory from waterfowl and muskrats. These two mats were placed in the deepest pond. Throughout the course of the six week trial, water samples were taken from both ponds, in addition to the two wells used for irrigation and the standard potting media. At the conclusion of the six week trial, all of the mats were removed from the locations described above. Plants were evaluated for survivability. Only the plants from within the enclosed mats were measured for growth.

6. Results

The majority of the plants grown in the floating mats survived and flourished (see table below). Of the plants used in ponds 1 and 2, a total of 89% survived. These plants were added to the nursery's inventory. With the exception of the water plantain (Alisma subcordatum), all species appeared to be very healthy. The water plantains that did not survive appeared to have been unsuccessful transplants. The narrow-leaved cattail (Typha angustifolia) and salt marsh bulrush (Scirpus robustus) showed evidence of being eaten. Eight of the ten species protected within the enclosures increased in height, some by approximately double. The two species that decreased in height had suffered die-back upon planting, but recovered to produce additional healthy stems.

From the San Domingo Creek mats, all plants except the marsh hibiscus (Hibiscus moscheutos) fared well enough to be returned to the nursery’s inventory. Of the five species chosen for this mat, the hibiscus is known to have the lowest tolerance for salinity. The smooth cordgrass (Spartina alterniflora) showed the most root growth. Pots in the mats used in San Domingo Creek accumulated barnacles over the course of the trial, necessitating the repotting of plants.

While the water quality data did not prove that the plants were taking up significant amounts of nutrients from the ponds, it was clear that sufficient quantities were available for the plants to produce new, healthy growth. Use of the floating mats has the potential to reduce nutrients from run-off while increasing nursery growing area and eliminating the need for fertilizers. Provision of seed stock and saleable plant material are added benefits of utilizing the floating mats.

7. Conditions

During 2005, reconstruction of the woody plant growing area adjacent to the pond took place. Increased density of plant material within the section creates the potential for increased nutrient run-off. Conversely, new, more efficient irrigation lines with cyclically programmed timers reduce the amount of run-off leaving the section.

Drought conditions during the 2007 growing season limited the amount of rain run-off to the ponds, so that any water reaching them contained only irrigation run-off, with the potential for a higher concentration of nutrients. It is difficult to determine the total load of nutrients entering the ponds with extremely low flow. As nutrients were added throughout the growing season, plants may not have been able to sustain the level of uptake necessary to balance out the nutrient level.

8. Economics

The total cost of the plant plugs transplanted into pots used for the mats is $275.90. With very little input (no watering, no initial or periodic fertilizing) and a relatively short growing time (six weeks), the plants rooted into the pots and produced saleable plants valued at $718. It is clear that we can make a profit cycling appropriate plants through the floating mat system throughout the growing season. Use of the ponds as a growing area will also expand the total nursery area, allowing us to grow a greater number of plants in a season.

9. Assessment

For future use, we can choose plant species that performed especially well in the floating mats, such as pickerelweed (Pontederia cordata). Since we did not utilize the entire area within the deepest nutrient management pond, we can also float a larger quantity of mats in future growing seasons.

10. Adoption

We plan to continue to use the floating mats within our nutrient management ponds to facilitate the uptake of excess nutrients. The overall survival rate of plants was high, and we will work towards an even higher survival rate in the future by planting species that tolerated the conditions well. As a supplier of wetland plant materials, it makes sense to utilize every extra inch of growing area to produce additional saleable wetland plant materials.

11. Outreach

Outreach began on July 13, 2004 with a presentation about the EC nursery’s nutrient management project to a Maryland Cooperative Extension Plant Clinic group. Extensive planning and preparation took place for the Maryland Nursery and Landscape Association’s Annual Field Day, held at EC on June 16, 2005 Over one hundred industry professionals were in attendance. The event included a presentation on nutrient management, focusing on EC’s nutrient management strategy. Tours of the facility were conducted throughout the day, providing an opportunity for participants to see and ask questions about the nutrient management ponds.

The Maryland Cooperative Extension will include results of the project in the early 2008 Talbot County newsletter. The Mid-Atlantic Grower, a publication dedicated to serving the nursery, greenhouse and horticultural industry, will share information about the nutrient management project with its readers in a special irrigation supplement in the March 2008 issue. The Maryland Nursery and Landscape Association has agreed to share educational information about the nutrient management project at EC with its industry membership base through their website and their printed periodical, the Free State Nursery and Landscape News May 2008 edition.

We have developed a brochure specifically about the floating mat aspect of our nutrient management program. This brochure was designed for mail distribution to approximately 300 nurseries and garden centers on the east coast. The brochure is also available at our booth at the Mid-Atlantic Nursery Trade Show and our information table at numerous conferences. Information from this brochure is also posted on the EC Nursery website with links to the SARE grant program and additional nutrient management projects underway.

Additionally, numerous groups of students, educators, and professionals (500 per year) have taken part in tours of the EC facility over the past few years. The concept of nutrient management and the methodology employed at the EC facility are integral parts of the tour. During the growing season, the tour includes demonstration of the floating rafts as they are being utilized for nutrient management purposes. Interested EC visitors are educated about creating their own productive and sustainable nutrient management pond. Signage that is currently being developed through a Maryland Department of Transportation grant will educate visitors in the future.

12. Report Summary

We chose to study the effectiveness of floating vegetation mats for nutrient uptake within nursery nutrient management ponds to improve water quality and increase revenue. Floating mats were planted with an assortment of herbaceous aquatic plants. Monitoring took place over a six week period. Plants were evaluated for survival and growth upon completion of the trial, providing insight on the effectiveness of the species chosen. Most of the plants survived and grew into a healthy, saleable product. A few species also produced seed that can be used to propagated new plants. Plants in the floating mats require very little input and a relatively short growing time. We can utilize the floating mats in nutrient management ponds (outside of a traditional growing area) to produce additional saleable wetland plant materials.