Updates to the Annual P Loss Estimator (APLE) model

Area of Science:

• Agricultural Science
• Environmental Modeling
• Soil Science

Background:

• The Annual P Loss Estimator (APLE) is a user-friendly, empirical model for predicting phosphorus (P) loss and soil test P changes.
• APLE's limitations include the inability to calculate runoff and its deterministic nature, which ignores input uncertainties.

Purpose of the Study:

• To enhance the APLE model by incorporating runoff estimation and uncertainty analysis.
• To provide users with a more realistic assessment of P loss and soil test P dynamics.

Main Methods:

• Modified APLE (ver. 3.0) to include runoff estimation via the Curve Number method.
• Implemented Monte Carlo simulations to quantify model input uncertainties.
• Applied the revised model to P loss and soil test P data from Mississippi and Maryland.

Main Results:

• The updated APLE successfully estimated runoff and quantified uncertainties in P loss predictions.
• Case studies demonstrated the model's utility in assessing P dynamics under different scenarios.
• Incorporating uncertainty analysis yielded a more realistic understanding of model performance.

Conclusions:

• The revised APLE (ver. 3.0) offers improved P loss and soil test P change estimations by integrating runoff calculation and uncertainty analysis.
• This enhanced model provides valuable insights for agricultural management and environmental protection.
• The approach highlights the importance of accounting for uncertainties in environmental modeling.