Nutrient Leaching From Soil in Mixed Turfgrass and Woody Plant Urban Landscapes.

Urban landscapes are frequently supplemented with nitrogen (N), phosphorus (P), and potassium (K) sources to encourage both growth and aesthetic appeal of the vegetation.  Landscape vegetation management practices that are least damaging to ground and fresh waters should be based upon an understanding of soil nutrient removal from leaching.  Mean nutrient concentrations of leachate from three amenity landscape vegetation coverage types were determined.  The experiment was conducted in Huntsville, TX using municipal water for irrigation. The vegetation types included three ratios, 20/80, 50/50, and 80/20, of turfgrass to woody plant coverage over the plot area.  Vegetation comprised St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kutze.], and three woody shrubs common to Texas.  Plots are in-ground lysimeters (1586 L) in a randomized complete block design with three blocks.  Treatments were installed on a Falba fine sandy loam (fine, montmorillonitic, thermic Typic Albaqualfs).  Plots are irrigated to replace 100% of calculated reference evapotranspiration minus rainfall.  Leachate will be collected every one to three weeks from Sept 2011 through Sept 2013, and N, P, and K, quantified.  Nitrate concentrations range from undetectable to 53 parts per million (ppm). Ortho-phosphate concentrations range from undetectable to 10.5 ppm.