Wisconsin's Role in Great Lakes Restoration - American Water ...

11. Snowmelt Export of Phosphorus from Cropland: Edge-of-Field Runoff Monitoring
Results from Pioneer Farm in Southwest Wisconsin
Randy S. Mentz, UW-Platteville Pioneer Farm, Platteville, WI, mentzr@uwplatt.edu
Paul M. McGinley, UW-Stevens Point, Center for Watershed Science and Education, Stevens
Point, WI, Paul.McGinley@uwsp.edu
Michael R. Penn, UW-Platteville, Department of Civil and Environmental Engineering,
Platteville, WI, mrpenn@uwplatt.edu
Dennis L. Busch, UW-Platteville Pioneer Farm, Platteville, WI, buschd@uwplatt.edu
Nonpoint phosphorus runoff is an increasingly important public and regulatory concern. While
most research on phosphorus runoff has focused on storm runoff, winter precipitation and
snowmelt runoff both can be sources of agricultural overland runoff and have the potential to
be significant contributors of nutrient export.
Winter runoff has been monitored since 2002 by researchers at Pioneer Farm. Pioneer Farm
is a 430-acre mixed-livestock farm associated with the University of Wisconsin-Platteville.
The headwaters of the Fever (Galena) River flow through the center of the farm. More than
90% of the watershed is in row crop agriculture and during snowmelt and winter rains, the
watershed is conspicuously dissected by intermittent streams that clearly convey water from
fields to the Fever River. Instrumentation at the edge of fields was installed to measure runoff
flow rates and sample water quality to estimate pollutant export.
Results from edge-of-field runoff monitoring indicate an average of 30 mm/year (1.2
inches/year) of winter runoff on these fields. During these events, the mean annual
phosphorus loss was 1.5 lbs/acre with more than 85% of the phosphorus in the dissolved
reactive form. The median suspended solids concentration is less than 50 mg/l. Although
significant phosphorus losses were measured over the study period, mean losses over time
were well under the 6 lb/acre benchmark in the Wisconsin Phosphorus Index.
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