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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Environmentally Integrated Dairy Management Research » Research » Publications at this Location » Publication #297235
Title: Monitoring runoff from cattle-grazed pastures for a phosphorus loss quantification tool

Author
item Vadas, Peter
item Powell, Joseph
item BUSCH, DENNIS - University Of Wisconsin
item Brink, Geoffrey

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2014
Publication Date: 11/3/2014
Citation: Vadas, P.A., Powell, J.M., Busch, D.L., Brink, G.E. 2014. Monitoring runoff from cattle-grazed pastures for a phosphorus loss quantification tool. Agriculture, Ecosystems and Environment. 199:124-131.

Interpretive Summary: Nitrogen and phosphorus loss from agriculture is a water quality impairment issue. For dairy farms, nitrogen and phosphorus can be lost from cropland, pastures, barnyards, and outdoor cattle lots. We monitored nitrogen and phosphorus loss in runoff from dairy and beef grazed pastures for two years in southwest Wisconsin, USA and tested the accuracy of the Annual Phosphorus Loss Estimator (APLE) model to predict runoff phosphorus from pastures using study and literature data. About 3-10% of annual precipitation became runoff from the pastures, and sediment loss was very low due to well established vegetation. Measured annual nitrogen and phosphorus loss in runoff was also low. APLE was able to reliably predict annual phosphorus loss in runoff. Our study increases the ability to develop reliable models that estimate the impact of cattle grazing pastures on nutrient runoff. This will be valuable in estimating whole-farm phosphorus loss from dairy production systems and identifying areas on dairy farms where phosphorus loss remediation should be targeted.

Technical Abstract: Nitrogen (N) and phosphorus (P) loss from agriculture persists as a water quality impairment issue. For dairy farms, nutrients can be lost from cropland, pastures, barnyards, and outdoor cattle lots. We monitored N and P loss in runoff from dairy and beef grazed pastures for two years in southwest Wisconsin, USA and tested the accuracy of the Annual P Loss Estimator (APLE) model to predict runoff P from pastures using study and literature data. About 3-10% of annual precipitation became runoff from the pastures, and sediment loss was very low due to well-established vegetation. Measured annual nutrient loss in runoff was also low, averaging 1.0 kg ha-1 for total P and 2.9 kg ha-1 for total N. Runoff sediment and non-dissolved N and P concentrations were well related to each other and tended to be greater in rainfall-induced runoff than snowmelt runoff. Conversely, dissolved N and P runoff concentrations were greater in snowmelt runoff. APLE was able to reliably predict annual P loss in runoff, estimating that the relative contribution to total pasture P loss was about 1/3 for both soil and dung derived soluble P, with the remaining 1/3 split equally between fertilizer P loss and soil erosion. Our study has increased the ability to develop reliable models for estimating the impact of cattle grazing pastures on nutrient runoff, which will be valuable in estimating whole-farm P loss from dairy production systems and identifying areas on dairy farms where P loss remediation should be targeted.