APLE2026: Development of a graphical user interface for the Annual Phosphorus Loss Estimator model

The Annual Phosphorus Loss Estimator (APLE) model is a commonly used annual time-step model for predicting annual field-scale surface runoff and erosion losses of dissolved and particulate P as well as annual changes in total and Mehlich-3 extractable soil P. APLE was developed and coded as an Microsoft Excel workbook to provide a modeling option for users with limited modeling experience and lack of access to expensive software packages. The advantage of using Excel is that most users have both access and familiarity with Excel. However, the calculations within Excel require numerous calls to multiple cells, making it a challenge to modify and update the model. Moreover, the graphics are limited, and the current version does not have the ability to compare model predictions with observations. This limits the model's use and functionality. To address this, we have developed a Graphical User Interface application of APLE (APLE2026) to provide a cleaner and more intuitive user interface, improved graphics, and enhanced data analysis. This novel software package of APLE provides a more seamless way to run the model and view model output enhancing the functionality of APLE.