Identifying environmental phosphorus risk classes at the scale of Prince Edward Island, Canada

Phosphorus (P) loss from agricultural land poses a major risk to the environment. The main objectives of this study were (i) to adapt a simple P saturation indicator using 141 soils that had contrasting P levels and to deduct critical environmental P values, and (ii) to identify environmental risk classes and their spatial and temporal distribution at the scale of Prince Edward Island, Canada. The P saturation index (PSI) was greatly influenced by the soil acidity, and two critical P saturation indices were identified (i) a PSI (P/Al)M-III of 19.2% for very to extremely acidic soils (pH   5.5). Above these critical values, P fertilization should be limited to crop requirements. Six environmental P risk classes from very low to extremely high were identified. Spatial distribution of the identified classes was performed using georeferenced soil data collected between 2003 and 2015. The moderate ...