Leachate Chemistry From Soil Under Turf and Native Grasses in Southern Texas.

Leaching of nitrogen (N), orthophosphate-P (P), and dissolved organic carbon (DOC) from soil represents a break in their respective nutrient cycles.  An understanding of nutrient removal from soil through leaching in amenity landscapes may lead to landscape management practices that are least damaging to surface and ground water.  We determined annual mean nutrient concentrations in leachate from landscapes planted with different urban vegetation types.  The experiment was conducted at two sites with different climates and irrigation water chemistry.  Vegetation comprised St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kutze.] alone, Red Oak [Quercus shumardii Buckl.] alone, St. Augustinegrass plus Red Oak, native grasses [Muhlenbergia capillaries (Lam.) Trin. and Schizachyrium scoparium (Michx.) Nash], and native grasses plus Red Oak in College Station (CS) and San Antonio (SA) Texas, on a Rader fine sandy loam (mixed, semiactive, thermic Aquic Paleustalfs).  Soil was systematically placed into lysimeters containing a drainage system and soil moisture probes.  Lysimeters (1136 L) were placed in-ground in a randomized complete block design with three blocks.  Leachate was collected every two to four weeks from May 2007 through April 2008, and N, P, and DOC, quantified.  Vegetative treatments had a significant effect on leachate nitrate and DON at CS, but no effect at SA.   Climate and irrigation water chemistry had a significant effect on some leachate chemistry, but this effect varied with the different vegetative species.