Chapter 1 Management Practices Affecting Nitrogen and Soluble Phosphorus Losses from an Upper Midwest Lawn

摘要

Public and regulatory agency concerns about the impacts of lawns on surface and groundwater quality were addressed in this 6-year study. The research site was a Kentucky bluegrass lawn established on a 6% slope at the University of Wisconsin-Madison turfgrass research facility. The lawn stand density maintained was sufficient to prevent sediment loss. Under these circumstances, depths of runoff ranged from 30-74 mm, or 5-9% of annual precipitation. Runoff inorganic N and soluble P losses ranged between 0.08-1.57 and 0.031-1.29 kg ha~(-1), respectively. Annual leachate nitrate-N concentrations were typically between 2 and 4 mg L~(-1) and the quantity of N leached averaged 3.9 kg ha~(-1). These N and P losses are intermediate between those from naturally vegetated and agricultural areas in the upper Midwest. Subsoil compaction and topsoil manipulation prior to lawn establishment did not affect runoff depths or N and P losses. This was attributed to the fact that over the duration of the study, 87% or more of the runoff and N and P losses occurred during the period of December through March. The single factor most strongly relating to runoff loss of N and P was depth of runoff. Failure to fertilize the lawn was second in importance. Impacts of other cultural practices such as chisel plowing of the compacted subsoil and type of fertilizer applied were of lesser importance.