2026/01/02 by Rachel Johnson, Anita M. Thompson, Eric G. Booth +3 · 1 voice
Agricultural and Biological Sciences · Environmental Science · #Hydrology and Watershed Management Studies #Soil and Water Nutrient Dynamics #Soil erosion and sediment transport
paper · pdf · doi:10.1080/00224561.2025.2607332
crossref issued 2026/01/02 · crossref published 2026/01/02 · crossref published-print 2026/01/02 · openalex publication_date 2026/01/02 · crossref published-online 2026/03/13 · crossref created 2026/03/13 · openalex created_date 2026/03/14 · crossref deposited 2026/04/03 · crossref indexed 2026/07/28 · openalex updated_date 2026/07/28
Legacies of historical land use and nutrient management can lead to stores of phosphorus (P) in watersheds that fuel eutrophic conditions in freshwater bodies, despite current management efforts. Temporal and spatial patterns of this “legacy” P accumulation depend on watershed-specific factors including land use history, hydroclimate, and socio-ecological characteristics. Thus, it is important to quantify P flows through watersheds over time to mitigate the long-term risk of lake water quality improvement. Here, we developed a P mass-balance with a Monte Carlo uncertainty analysis to quantify P flows and storage over three decades in the agricultural watershed of Green Lake, Wisconsin’s deepest natural inland lake. Our results show that between 1987 and 2017, the watershed’s net P balance shifted from accumulation to depletion. The percentage of annual P inputs retained decreased from 70% to –31%, suggesting that the watershed may be drawing down legacy P stored from previous years. This shift to depletion occurred despite P additions remaining high, sourced largely from agricultural fertilizer and dairy feed supplements. Over the study period, net removals increased by 100%, driven by increases in P removal by crops and by declining livestock populations that led to feed crops being exported out of the watershed. Thus far, few agricultural watersheds have been documented to be in legacy P depletion phases, and this is an important finding for future research on effective watershed management.