| Abstract: | Oxygen-18-labeled phosphate (OLP) and natural abundance 18O have been used as tools for elucidating the dynamics of phosphorus (P) in soils, yet much remains poorly understood. The objective of this research was to determine the extent of preferential soil sorption across the range of species contained within OLP. A variety of soils were shaken with water containing 65.5 mg L?1 OLP-P for a 24-h period. Following shaking, the OLP species remaining in the solution were determined. Increasing the oxygen-18 atoms in the phosphate molecule by one resulted in a 1.8% increase in the amount of that OLP species sorbed to the soil, and this increase in sorption was uniform across soils. A strong correlation (r2 = 0.94) was found between the amount of phosphate sorbed and the Mehlich 3 P saturation ratio of the soil. These results will be useful for studies using natural abundance and enriched 18O-phosphate in soils. |
