Carbon, Nitrogen, and Orthophosphate Leaching from Soil under Single- and Mixed-species Landscapes

Abstract

Effective landscape management practices in urban landscapes must include an awareness of nutrient removal from soil caused by leaching, and these practices should be those least damaging to freshwaters. Annual mean dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate-N, ammonium-N, soluble phosphate, and bicarbonate concentrations and fluxes were quantified in leachate from landscapes planted with different urban horticultural types. Plot vegetation consisted of either a single species or mixed species. The experiment was conducted at two sites in Texas with significantly different irrigation water chemistry. At the two sites, plant species had a significant effect on PO43--P flux, and irrigation chemistry had a significant effect on all nutrient fluxes. There was an interaction between plant species and irrigation chemistry for PO43--P flux (P < 0.05) only. The relationship between bicarbonate and DOC flux at sites was stronger and significant (0.92; P < 0.05) at the site irrigated with Na-HCO3 municipal tap water than at the site irrigated with Ca-HCO3 municipal tap water (R2 = 0.76, P = 0.05). Type of irrigation water chemistry may result in lower plant water uptake resulting in increased nutrients lost to leachate.