Fertilization and Runoff from Urban Lawns
Project Number: BQY15
Project Chief: Todd Stuntebeck
Project Topics: phosphorus
Cooperators: Wisconsin Department of Natural Resources
Period of Project: April 1999–Continuing
Problem
Excessive phosphorus entering lakes is known to promote unsightly weed growth, decrease recreational uses, and ultimately speed the eutrophication process. Structural or “end-of-pipe” management practices designed to reduce phosphorus are generally expensive. Reducing phosphorus at the source may be a less-expensive alternative. Restricting fertilizer use in the watershed to phosphorus-free brands would seem to be a potentially inexpensive way to reduce phosphorus loads to Lake Wingra. However, there is little applicable field evidence supporting the hypothesis that runoff from fertilized lawns is greater in phosphorus concentrations than runoff from non-fertilized lawns. A better understanding of how much water runs off a typical urban lawn and under what conditions will help watershed investigators to improve their ability to predict the impacts of management decisions.
Objectives
Two phases of the project have been completed. The first phase objective was to determine differences in concentrations of total phosphorus, dissolved phosphorus, suspended solids, and total solids between 15 fertilized and 15 non-fertilized lawns in the Lake Wingra basin. The second phase objective was to determine differences in concentrations and loads of these constituents in runoff from 5 lawns in this same basin. A final phase is to determine the major variables affecting runoff from urban lawns. Three variables of specific interest are antecedent soil moisture conditions, soil compaction, and slope length.
Lawn-runoff samples were collected from 30 water-quality samplers between May 1999 and September 2001. Fifteen of the samplers were located in lawns that were fertilized, and the other 15 were in lawns that were not fertilized.
Approach
Six turf grass plots at the O.J. Noer Research and Education Facility in west Madison and two plots at residences in the Lake Wingra basin will be instrumented with tipping-bucket apparatus to measure the timing, magnitude, and intensity of runoff. A nearby meteorological station will be equipped with precipitation, soil moisture and soil temperature instruments. Runoff will be measured in both frozen-ground and non-frozen ground periods.
Progress
- Wrote datalogger program and assisted graduate student at installing meteorological station at O.J. Noerr.
- Have collected the data at the meteorological station several times to assure program and instrumentation were working correctly.
- Wrote Excel macros to assist with parsing/organizing data from the datalogger
Plans
Continue to assist graduate student with equipment installation, datalogger programming, and data organization as needed.
Publications and Reports
TBD
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