The addition, storage, and flow of ‘anthropogenic’ phosphorus (P) is a major challenge for environmental management. While mineral P fertilizers are essential to agricultural production, P mined from phosphate rock is a non-renewable resource and P added to agricultural fields can runoff into surface waters and contribute to harmful algal blooms, such as the bloom that shut down the Toledo, Ohio municipal water supply in August 2014. The application of P fertilizers is often inefficient, as much of the P forms complexes with soil particles and is unavailable to plants. In addition, some of the P from previous fertilizer applications remains bound to soil particles from year to year, becoming “legacy P”. After several years of fertilization, a soil may become saturated with P, at which P inputs to surface waters may increase—either by erosion of soil particles into waterways, or by runoff of dissolved P that does not bind to P-saturated soils. However, the benefits of sustainable P use and management for society due to its downstream impacts on multiple ecosystem services often do not receive sufficient consideration.
We propose a conceptual framework—the “phosphorus-ecosystem services cascade” (PESC)—to integrate key ecosystem processes and functions moderating the relationship between anthropogenic P and ecosystem services at distinct spatiotemporal scales. As anthropogenic P cascades through terrestrial ecosystems and into waterways, it can impact critical ecosystem services. However, improving the sustainability of P stewardship can benefit ecosystem services impacted by P via synergies with other societal or management goals (e.g., recycling of livestock manures and organic wastes may enhance soil carbon storage). We used the PESC framework to identify key research priorities to align P stewardship with the management of multiple ecosystem services, such as incorporating additional services into agri-environmental P indices, assessing how widespread recycling of organic P sources might impact agricultural yields and water quality, and accounting for shifting baselines in P stewardship due to climate change. Empirical data from different contexts is needed to test the hypothesized relationships between P and ecosystems services at different scales. Because P impacts depend on management and site-specific biogeophysical properties, greater precision in targeting stewardship strategies to specific locations and/or site properties would help to optimize manage for ecosystem services and to more effectively internalize the downstream costs of nutrient management.