Application of animal manure beyond crop uptake can lead to accumulation of phosphorus (P) in the plow layer. It is uncertain whether resulting high levels of soil test P represent an increased risk of P loss due to other effects of manure addition on soil chemistry. We quantified P losses via subsurface vertical leaching in undisturbed soil cores from naturally acidic soils with a dairy or poultry manure application history of up to 40 yr. One background, 4 poultry litter (PL) and 4 dairy manure (DM) amended fields were selected and three intact cores (50 cm height, 30 cm diameter) were collected per field. Soils were Wellsboro or Oquaga channery silt loams and ranged in Mehlich-3 extractable P (M3P) from 79 to 2924 mg P kg-1. Cores were irrigated once every week for 6 mo with deionized water at a rate matching a New York Southern Tier 1 hr -1 yr storm. In the first week, average leachate dissolved reactive P (DRP) from DM soils and PL soils ranged from 0.073 – 1.83 mg L-1 and 0.073 – 1.11 mg L-1 respectively. In DM soils, average leachate DRP concentrations returned to background levels after three weeks of irrigation. Leachate from the poultry field with the highest M3P increased in DRP over time, peaking at 10.34 mg L-1, possibly due to dissolution of calcium phosphates and lowering of soil pH. Results show that leaching can be a significant mechanism of P loss which may increase over time if soils are taken out of cropping rotations and allowed to return to their naturally acidic state.
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