This research was undertaken to investigate a novel approach to environmental phosphorus assessment using both chemical modelling techniques and digital soil mapping methods. A chemical model was developed to predict the partitioning of adsorbed and aqueous forms of inorganic phosphate within mineral soils of a small agricultural catchment within the Rondeau Bay watershed. This model accounts for changes in soil pH as well as clay and iron content. The resulting model was most accurate over the pH range 5 to 8. The second focus of this research project was an assessment of digital soil mapping approaches used to predict the spatial distribution of soil pH, clay content, iron content, and Olsen-extractable phosphorus across the study area. The results indicate that point observations used in conjunction with data that describes topographic position, parent material, and land management are suitable for accurately predicting these soil attributes at the within-field scale on a field-by-field basis.