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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Soil Management and Sugarbeet Research » Research » Publications at this Location » Publication #418459
Research Project: Agricultural Management for Long-Term Sustainability and Soil Health

Location: Soil Management and Sugarbeet Research

Title: Combining soil conservation with phosphorus drawdown can confront legacy P accumulation and transfer

Author
item Mott, Joshua
item Simpson, Zachary
item Bolster, Carl
item FAULKNER, JOSHUA - University Of Vermont
item King, Kevin
item Osterholz, William
item Williams, Mark
item Dalzell, Brent
item DOLPH, CHRISTINE - University Of Minnesota
item Feyereisen, Gary
item DURIANCIK, LISA - Natural Resources Conservation Service (NRCS, USDA)
item Kleinman, Peter
item Miner, Grace

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Managing phosphorus in agricultural systems must balance the benefit of this fertilizer nutrient with its liability as a pollutant in downstream water bodies. Phosphorus management can be additionally challenging as a result of “legacy phosphorus”, that is phosphorus that has accumulated in the environment from past production activities. Legacy phosphorus in agricultural soils can resist conventional nutrient management strategies to improve water quality. Scientists from the USDA Legacy Phosphorus Assessment Project explored management options for addressing legacy phosphorus in the Lake Champlain, Lake Erie and Mississippi River watersheds. They recommend stacking practices aimed at reducing legacy phosphorus with conventional conservation management to achieve the most robust conservation outcomes.

Technical Abstract: Legacy phosphorus (P) in agricultural soils can resist conventional nutrient management strategies to improve water quality. We sought to model trade-offs in legacy P mitigation efforts at key sites in the northern United States where legacy P contributions to water quality are a concern. The Annual P Loss Estimator (APLE) was used to simulate generalized management scenarios: current practices; conventional conservation practices; and P drawdown. Results highlight that effects of legacy P are not always obvious; even at sites near the range of agronomic optimum, losses of legacy P in runoff can be significant. P drawdown offers the potential to deplete legacy P stores but requires dedication and time. Focusing on either soil conservation or soil P drawdown alone is insufficient to meet water quality goals. Drawdown practices must be accompanied by practices supporting soil conservation to ensure that legacy P management benefits water quality in the short- and long-term.