UNDERSTANDING AND PREDICTING THE IMPACT OF AGRICULTURE ON THE ENVIRONMENTAL INTEGRITY OF MANAGED WATERSHEDS
Location: Water Quality and Ecology Research
Title: Evaluating plant species-specific contributions to nutrient mitigation in drainage ditch mesocosms
Submitted to: Water, Air, and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 2010
Publication Date: April 18, 2011
Citation: Moore, M.T., Kroger, R. 2011. Evaluating plant species-specific contributions to nutrient mitigation in drainage ditch mesocosms. Water, Air and Soil Pollution. 217:445-454.
Interpretive Summary: Excessive nutrients can leave farm fields following storm events and contaminate rivers, lakes, and ponds near agricultural fields. Management practices to reduce this possibility are needed in the agricultural production landscape. The current study examined the use of different aquatic plants commonly found in drainage ditches to reduce the amount of nutrients from runoff water. Results demonstrated that no single plant type was more efficient at decreasing both the amount of nitrogen and phosphorus in water; however, plants were able to decrease the amount of nutrients in runoff water. This is an important discovery for conservation leaders who are working with landowners in decreasing the amount of nutrients leaving their fields.
Eutrophication of surface water bodies is a concern not only in the United States, but also worldwide. In the US alone, excessive nutrients are blamed for nearly 5700 impairments of surface water bodies. Each year nearly 17.5 million tons of nitrogen (N) are attributed to animal manure and mineral fertilizer use in the 15 European Union (EU) nations, leading to potential water quality problems in the North Sea and other aquatic resources. Innovative measures, such as maximizing drainage ditch nutrient retention, are being examined to decrease the amount of N and phosphorus (P) running off agricultural lands and into aquatic receiving systems. Experimental mesocosms (1.25 m x 0.6 m x 0.8 m) were filled with sediment and planted with monocultures of one of six obligate wetland plant species [Typha latifolia (broadleaf cattail), Panicum hemitomon (maidencane), Thalia dealbata (powdery alligator-flag), Echinodorus cordifolia (creeping burhead), Myriophyllum spicatum (Eurasian watermilfoil), and Saururus cernuus (lizard’s tail)], while three replicates were left non-vegetated to serve as controls. Mesocosms were amended with 5 mg L-1 of N and P species over a 4 h hydraulic retention time. Following the 4 h amendment, unamended water was flushed through mesocosms for an additional 8 h to assess residual leaching of nutrients. Outflow water concentrations and loads were reduced for all N and P species. In certain cases, there were significant differences between plant species; however, for the majority, there was no statistical difference in percent reduction between plant species. While native aquatic vegetation shows promise for mitigation of nutrient runoff, further studies altering the hydraulic retention time for improved efficiency should be conducted.