Nutrient leaching during establishment of simulated residential landscapes

Research evaluating nutrient losses during the establishment of plant material in mixed residential landscapes is limited. The objectives of this study were to determine the effect of vegetative cover type, compost application, and tillage on nutrient losses during the establishment of landscape plants. Twenty-four small plots constructed with subsoil fill were planted with St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] and mixed ornamental species in a randomized complete block design. Plots received composted dairy manure solids at a rate of 0 or 50.8 m³ ha^-1 in combination with shallow tillage or aeration. Cumulative leachate loads and flow-weighted mean concentrations of NH₄-N, NO₃ + NO₂-N, and dissolved reactive P (DRP) were calculated periodically and annually to assess nutrient leaching from landscape plots. Higher cumulative leachate volume, inorganic N and DRP loads, and mean NO₃ + NO₂-N and DRP concentrations were observed under ornamental cover during one or more study periods, which we attribute to differences in root density and shoot biomass between mixed ornamental species and turfgrass during establishment. Greater cumulative leachate inorganic N loads were reported from composted soils than from unamended soils or soils receiving only tillage or aeration. Inorganic N and DRP loads were similar in magnitude to reported leaching losses from agricultural systems. Better management of nutrients and water in woody ornamental plant beds during plant establishment is needed due to differences in plant growth habits compared with turfgrass. Nutrient content of organic amendments should be considered when applying these materials as a soil conditioner in new residential landscapes.