Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Abstract. In assessing how the output of a numerical model is influenced by its input parameters, sensitivity analysis provides a guideline in identifying and selecting key parameters while calibrating the model. Recently developed RZWQM2-P model, integrating a new phosphorus (P) module into the RZWQM2 model, was shown to successfully simulate P losses through surface runoff and tile drainage under different agricultural management practices. No global sensitivity analysis was performed for the newly developed RZWQM2-P model‘s simulation of P losses, leaving key parameters governing P losses simulation unidentified. The present study‘s objective was to address this shortcoming. Morris screening and Sobol-variance-based sensitivity analysis methods were applied to the prediction of dissolved reactive P (DRP) and particulate P (PP) losses through surface runoff and tile drainage. Data were collected from a liquid cattle manure applied experimental field with maize and soybean rotation in Ontario, Canada. Macroporosity proved to be a sensitive parameter in simulating P losses in all forms and from all outlets, while DRP loss through surface runoff was most sensitive to the P extraction coefficient, and PP loss through surface runoff was mainly governed by Universal Soil Loss Equation (USLE) parameters. Tile flow DRP and PP losses were most sensitive to the plant P uptake distribution parameter and the soil detachability coefficient, respectively. These results will inform the development of guidelines for RZWQM2-P model calibration.