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.