See more from this Session: Resource Management and Monitoring: Impact On Soils, Air and Water Quality and General Environmental Quality (Graduate Student Poster Competition)
Monitoring edge-of-field runoff in a northern climate with below-freezing temperatures presents a number of unique challenges. Ice formation and snow obstruction during runoff events can introduce major errors in discharge estimations and sample collection unless appropriate methods are used. Methods developed from our experience in preventing and compensating for frost heave, ice dams, flume submergence, frozen sample lines, and electronic malfunctions will be discussed.
Results from edge-of-field runoff monitoring indicate an average of 30 mm/year (1.2 inches/year) of winter runoff on these fields. Winter runoff commonly accounts for greater than 50% of the annual runoff. During these events, the mean annual phosphorus loss was 1.7 kg ha-1 with more than 85% of the phosphorus in the dissolved reactive form. The maximum phosphorus yield was 7.8 kg ha-1. The median suspended sediment concentration is less than 50 mg/l. Although significant winter phosphorus losses were measured over the study period, mean losses over time were well under the 6.7 kg ha-1 benchmark in the Wisconsin Phosphorus Index.