Estimating legacy soil phosphorus impacts on phosphorus loss in the chesapeake bay watershed

Peter A. Vadas, Nicole M. Fiorellino, Frank J. Coale, Robert Kratochvil, Alisha S. Mulkey, Josh M. McGrath

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Agricultural nutrient management is an issue due to P loss from fields and water quality degradation. This is especially true in watersheds where a history of P application in excess of crop needs has resulted in elevated soil P (legacy P). As practices and policy are implemented in such watersheds to reduce P loss, information is needed on time required to draw down soil P and how much P loss can be reduced by drawdown. We used the Annual P Loss Estimator (APLE) model to simulate soil P drawdown in Maryland, and to estimate P loss at a statewide scale associated with different combinations of soil P and P transport. Simulated APLE soil P drawdown compared well with measured rates from three field sites, showing that APLE can reliably simulate P dynamics for Maryland soils. Statewide APLE simulations of average annual P loss from cropland (0.84 kg ha-1) also compared well with estimates from the Chesapeake Bay Model (0.87 kg ha-1). The APLE results suggest that it is realistic to expect that a concerted effort to reduce high P soils throughout the state can reduce P loss to the Chesapeake Bay by 40%. However, P loss reduction would be achieved gradually over several decades, since soil P drawdown is very slow. Combining soil P drawdown with aggressive conservation efforts to reduce P transport in erosion could achieve a 62% reduction in state-level P loss. This 62% reduction could be considered a maximum amount possible that is still compatible with modern agriculture.

Original languageEnglish
Pages (from-to)480-486
Number of pages7
JournalJournal of Environmental Quality
Issue number3
StatePublished - May 1 2018

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Management, Monitoring, Policy and Law


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