Nutrient Management The Water Quality Improvement Act of 1998 required that anyone "who, in operating a farm, uses chemical fertilizer" must have a nitrogen and phosphorus based plan by December 31, 2001, which must be implemented by December 31, 2002. The nursery at Environmental Concern takes great care to limit the possibility of any nutrient runoff from the irrigated growing area. Early in 2000, Environmental Concern constructed a series of three nutrient management ponds on the property. The purpose of these ponds is to collect any runoff from the overhead irrigation sections of the nursery, and to allow any nutrients and sediments to settle out. 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, and therefore can be programmed cyclically to avoid over-watering and potential nutrient leaching. The runoff that does reach the nutrient management ponds contains little nutrient input. Frequently the flow is not great enough for any water to reach the outflow of the ponds. Any overflow from the last of the three ponds will drain across 160 feet of grasses and wooded area before reaching the nearest surface water. EC’s nutrient management plan was submitted as required by law to the MDA, and written by an independent nutrient management planner certified and licensed by the MDA. As a result of the nutrient management and fertilization practices utilized, Environmental Concern’s nursery operations have been classified as a “low management risk.” Floating Mat Experimentation Grant funding from the USDA’s Sustainable Agriculture Research and Education Farmer/Grower Grant and the Mid-Shore Community Foundation provided us with the opportunity to experiment with floating vegetation mats that could potentially increase the amount of nutrient uptake in the nursery’s nutrient management ponds.
During the first growing season, two types of polyethylene foam floating mats, purchased from Maryland Aquatic Nurseries, were evaluated. The first model holds a section of coir blanket in which plants can be directly planted, while the second has die-cut holes in which potted plants can be suspended. Based on observations at the University of Maryland Center for Environmental Sciences and several months of testing both types of mats, the second model was determined to be more cost-effective for our purposes, and easier to handle. During the second growing season, ten species of wetland plants were selected to be planted in the mats, based on their 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 into standard quart pots containing media without fertilizer. Two sets of plants were measured prior to placement in the mats, and enclosed with wire mesh to prevent possible herbivory. 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 and the standard potting media. The majority of the plants grown in the floating mats flourished, and were added to the nursery's inventory. Two species 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 from the initial measurements suffered die-back upon planting and recovered to produce additional healthy stems. From the San Domingo Creek mats, most plants fared well enough to be placed back into the nursery’s inventory. Pots in the mats used in the 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 a significant amount of nutrients from the ponds, it was clear that sufficient nutrients were available for the plants to produce new, healthy growth. Use of the floating mats has the potential to reduce nutrients from runoff 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. For More Information: USDA Sustainable Agriculture Research and Education Grant Program http://www.uvm.edu/~nesare/FGinfo.html Chesapeake Bay Program info on nutrient pollution http://www.chesapeakebay.net/info/nutr1.cfm University of Maryland Center for Environmental Sciences use of aquatic plants for nutrient management http://www.hpl.umces.edu/SARE/maryland.html Maryland Aquatic Nurseries, Inc. floating raft products http://www.marylandaquatic.com USDA ARS Southeast Watershed Research on vegetative mats for swine lagoons http://www.ars.usda.gov/research/projects/projects.htm?
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