Document: JOH-3-59-48

Does St. Augustine grass lose more nitrogen via runoff and leaching than a lower-maintenance mixed-species landscape?

ERICKSON, J.E.* 1,2, J.C.VOLIN 1, J.L.CISAR 2 and G.H.SNYDER 2

Florida Atlantic University, Davie, FL, U.S.A. 1
University of Florida, Fort Lauderdale, FL 33314, U.S.A. 2

Abstract:
Leachate and runoff from residential landscapes on sandy soils may contain substantial levels of nitrogen and other applied nutrients. Therefore, a study was initiated to examine inorganic N losses in leachate and runoff between St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) and a mixed-species landscape consisting of ground covers, shrubs, and trees. Eight plots, four replications of each treatment, were created at a 10% slope using a medium-fine sand. A granular fertilizer was applied to both landscape treatments. The turfgrass was fertilized at a rate of 300 kg N ha-1 yr-1 and the mixed-species landscape at a rate of 150 kg N ha-1 yr-1. Runoff was collected and analyzed for volume, NH4-N, NO3-N. Overall, runoff volume and nutrient losses were extremely low. Measurable runoff was collected during only one intense rainfall event. No significant difference (p < 0.01) in runoff loss of inorganic N between the treatments was observed. Monthly ET was determined by subtracting the measured leachate from irrigation and precipitation. Following establishment of the mixed-species landscape, no significant differences in ET were observed. Composite daily leachate samples were collected and multiplied by the leachate volume for the respective 24-hour period to give a daily nutrient loading for each plot. Annual leachate N losses were significantly higher on the mixed-species landscape, resulting in 4.83 g N m2 -1 yr-1 compared to 0.23 g N m2 -1yr-1 for the St. Augustine grass. These results reflect the longer establishment period required by the mixed-species landscape.

Keywords: Pollution

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This abstract is being presented at: 4:00 PM in session:
Oral Session #49: Linkages Between Land and Streams.