Abstract 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.
Byrnes et al. (Wed,) studied this question.