title: Simulating soil phosphorus dynamics for a phosphorus loss quantification tool.
abstract: Pollution of fresh waters by agricultural phosphorus (P) is a water quality concern. Because soils can contribute significantly to P loss in runoff, it is important to assess how management affects soil P status over time, which is often done with models. Our objective was to describe and validate soil P dynamics in the Annual P Loss Estimator (APLE) model. APLE is a user-friendly spreadsheet model that simulates P loss in runoff and soil P dynamics over 10 yr for a given set of runoff, erosion, and management conditions. For soil P dynamics, APLE simulates two layers in the topsoil, each with three inorganic P pools and one organic P pool. It simulates P additions to soil from manure and fertilizer, distribution among pools, mixing between layers due to tillage and bioturbation, leaching between and out of layers, crop P removal, and loss by surface runoff and erosion. We used soil P data from 25 published studies to validate APLE's soil P processes. Our results show that APLE reliably simulated soil P dynamics for a wide range of soil properties, soil depths, P application sources and rates, durations, soil P contents, and management practices. We validated APLE specifically for situations where soil P was increasing from excessive P inputs, where soil P was decreasing due to greater outputs than inputs, and where soil P stratification occurred in no-till and pasture soils. Successful simulations demonstrate APLE's potential to be applied to major management scenarios related to soil P loss in runoff and erosion.
authors.affiliation: US Dairy Forage Research Center, Madison, WI, USA. peter.vadas@ars.usda.gov
authors.forename: Peter A
authors.initials: PA
authors.lastname: Vadas
authors.forename: Brad C
authors.initials: BC
authors.lastname: Joern
authors.forename: Philip A
authors.initials: PA
authors.lastname: Moore
mesh_terms: D003198:Computer Simulation; D055593:Geological Phenomena; D008962:Models, Theoretical; D010758:Phosphorus / Q000737:chemistry*; D015203:Reproducibility of Results; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus