Submitted to: Journal of Nutrient Management
Publication Type: Trade Journal
Publication Acceptance Date: 6/26/2023
Publication Date: 11/3/2023
Citation: Young, E.O. 2023. Runoff water quality in hay and pasture systems. Journal of Nutrient Management. 4(4):14-16.
Technical Abstract: Cropping systems affect farm profitability along with several important agronomic and environmental outcomes. While it is well established that rotating from annual to perennial crops decreases erosion and particulate phosphorus loss, less is known about nutrient loss and runoff water quality differences between perennial hay forage and grazing systems. A study was conducted at the Marshfield Agricultural Research Station to quantify nutrient loss and water quality differences for three grazing systems (continuous grazing, permanent paddock grazing; PPG and adaptive multi-paddock grazing; AMP) and a hay field using a paired watershed analysis. Continuous grazing provided full pasture access, whereas PPG divided the pasture into three zones and rotated heifers every 10 to 15 days based on regrowth. Heifers were fenced in smaller areas and moved every one to three days for AMP. The four fields were managed the same during calibration (2013 to 2017) with three hay cuttings and liquid dairy manure applied once or twice per year. Grazing treatments (5 heifers/pasture) were randomly assigned to hay fields in May 2018 with runoff monitored until November 2020. Results showed that AMP had lower cumulative runoff and sediment loss compared to other treatments, with losses similar in magnitude to the control field (hay). Continuous grazing had significantly greater runoff and sediment loss in addition to greater nitrogen concentrations and loads compared to the control. Similar trends were evident for total and dissolved reactive phosphorus, with higher losses for continuous grazing and lower losses for AMP and the control. Results for nitrogen and phosphorus varied for rain versus snow events depending on grazing treatment. Overall, results suggest that nutrient loss and surface runoff water quality for AMP was closest to the control hay field.