Does a Mixed‐Species Landscape Reduce Inorganic‐Nitrogen Leaching Compared to a Conventional St. Augustinegrass Lawn?

Low maintenance vegetation may reduce N leaching following establishment compared to routinely fertilized conventional turfgrass lawns. Therefore, using a field‐scale facility we examined N leaching from contrasting residential landscape models established on a sandy soil. Four replications each of a St. Augustinegrass [ Stenotaphrum secundatum (Walt.) Kuntze] monoculture (SA) and a mixed‐species (MS) landscape were randomly assigned to 47.5‐m 2 plots. Fertilizer N was applied to the SA landscape bimonthly at a rate of 50 kg ha −1 (total of 900 kg N ha −1 ), while the MS landscape was fertilized bimonthly at a rate of 40 kg N ha −1 only during establishment (total of 480 kg ha −1 ). Data were collected for 3 yr (16 mo to 52 mo after planting). Cumulative mean inorganic‐N leached was 4.1 kg ha −1 and 7.4 kg ha −1 for the SA and MS landscapes, respectively. Relatively long establishment requirements for the MS landscape led to significantly greater inorganic‐N leaching (5.2 kg ha −1 ) in year 1 of the study compared to the SA landscape (1.3 kg ha −1 ). After year 1, inorganic‐N leaching was comparable on both landscapes, although it was significantly less on the MS landscape in year 3 when no fertilizer was applied. Overall, inorganic‐N leaching was low (<2% of applied N) on both landscapes following establishment, indicating the importance of management practices rather than species composition for reducing N leaching from residential land use.