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ARS Home » Midwest Area » Bowling Green, Kentucky » Food Animal Environmental Systems Research » Research » Publications at this Location » Publication #429191
Research Project: Developing Agronomically and Environmentally Beneficial Management Practices to Increase the Sustainability and Safety of Animal Manure Utilization

Location: Food Animal Environmental Systems Research

Title: APLE2026: Development of a graphical user interface for the annual phosphorus loss estimator model

Author
item Bolster, Carl
item Vadas, Peter

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2026
Publication Date: 2/13/2026
Citation: Bolster, C.H., Vadas, P.A. 2026. APLE2026: Development of a graphical user interface for the annual phosphorus loss estimator model. Journal of Environmental Quality. 55(1). Article e70154. https://doi.org/10.1002/jeq2.70154.
DOI: https://doi.org/10.1002/jeq2.70154

Interpretive Summary: Phosphorus (P) is an essential nutrient for crop growth and in many soils P concentrations in the soil are not adequate for maximizing crop growth. As a result, P is often applied to agricultural fields to maximize productivity. However, the overapplication of P can lead to soil accumulation of P over time. Because freshwater bodies are also often P-limited, if this soil P is remobilized and transported to waterways it can accelerate eutrophication leading to fish kills and reduced recreational value of the receiving waterbodies. Models are often used to help evaluate the risk of a given agricultural field to releasing P into runoff during rain events and thus to identify fields that should be avoided. The Annual P Loss Estimator (APLE) is a simple spreadsheet model developed for predicting annual field-scale dissolved and particulate P loss in surface runoff as well as annual changes in plant-available P. This model was designed to provide a relatively easy-to-use tool for those without significant modeling experience. However, in it's current form as an Excel spreadsheet, the model is limited in how it provides users with model predictions as well as makes it difficult for users to understand and modify the basic equations used in the model. To address this problem, I have developed a graphical user interface (GUI) for APLE that provides a more seamless way to run the model and view and interpret model results. This will allow for improved decisions

Technical Abstract: The Annual P Loss Estimator (APLE) model is an annual time-step model for predicting annual field-scale loss of dissolved and particulate P as well as annual changes in Mehlich-3 extractable soil P. This model has been used extensively and has produced reasonably good predictions of both annual P loads and changes in soil test P at a variety of sites. In addition, this model has been used to evaluate and improve P site indices – a simple tool used by many states to evaluate risks of P loss and to guide in P management strategies to protect water quality from P runoff from agricultural fields. APLE is currently only available as an Excel spreadsheet. The advantage of using Excel is that most users have both access and familiarity with Excel. However, the coding within Excel is very difficult to follow as there are multiple calls to numerous cells making it nearly impossible for users to modify and to update the model. Moreover, the graphics are limited, and the current version does not calculate goodness-of-fit statistics. This limits the model’s use, accessibility, functionality, and adaptability. To address this, I have developed a windows-based desktop application of APLE (APLEWin2025) to provide a cleaner interface, improved graphics and output capabilities, greater transparency of the governing equations, and easier update ability.