https://doi.org/10.1029/2025GB008893

Byrnes, D. K., Van Meter, K. J., Chang, S. Y., & Basu, N. B. (2026). Balancing legacy and efficiency: Present and historical phosphorus management across the United States. Global Biogeochemical Cycles, 40, Article e2025GB008893. https://doi.org/10.1029/2025GB008893

Phosphorus (P) is essential for food production but poses persistent environmental risks due to overapplication and accumulation in agricultural landscapes. Despite decades of management efforts, P losses continue to degrade water quality across the United States. In this study, we use a high-resolution 250 m gridded data set (gTREND-P) spanning 1930–2017 to assess long-term trends in agricultural P use through three complementary indicators: phosphorus use efficiency (PUE), annual P surplus, and cumulative surplus. We identify strong regional patterns: livestock-dominated regions in the East, and parts of the Midwest exhibit low PUE and high cumulative surplus due to persistent manure inputs. In the central Midwest, fertilizer-intensive crop systems have also led to substantial P accumulation, contributing to large legacy surpluses despite recent improvements in PUE. In some areas, PUE values exceed 1, suggesting that crop uptake is increasingly supported by soil P reserves rather than current inputs. To better capture both historical and contemporary dynamics, we introduce a quadrant framework that integrates PUE and cumulative surplus to classify agricultural land into four states: Intensification, Recovery from Overapplication, Recovery from Soil Depletion, and Unsustainable Use. This typology reveals spatial shifts over time, with 19% of US croplands transitioning from Intensification to Recovery from Overapplication between 1980 and 2017, while 60% remain in the “Intensification” state, often driven by high manure inputs. Our findings highlight the need for regionally tailored parcel-level P management strategies that recognize the legacy effects of past practices while enabling targeted interventions for sustainable P use.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB008893