Phosphorus is known to be an important contributor to eutrophication of aquatic systems, but the role of organic phosphorus is often overlooked. This review uses a meta-analysis approach to investigate inorganic and organic phosphorus in organic fertilizers, soils and waters, including the quantification of organic phosphorous forms such as monoesters, diesters, and inositol hexakisphosphate. Across these media, organic phosphorus comprised 22–46% of the total phosphorus (by mass of phosphorus). Bioavailable organic phosphorus appears to be more mobile than recalcitrant forms. Organic phosphorus may represent a significant risk for eutrophication, and the risk may vary according to the season, but conclusions are hampered by a lack of data.