Nitrate, Phosphate, and Potassium Movement into Drainage Lines Under Three Soil Management Systems1
- D. V. Calvert2
Nitrate, orthophosphate, and potassium concentrations in drainage water were determined from subsurface drains installed in shallow-tilled (ST), (15 cm); deep-tilled (DT), (107 cm); and deep-tilled and limed (DTL) Florida Oldsmar sand planted to citrus (Citrus sp.). The drainage water samples were collected during the period May 1971 through July 1972. Total discharge of NO3-N was significantly greater from ST plots than either DT or DTL plots. The NO3-N in the drainage water from all treatments ranged from < 1 – 8 mg/liter during the period of study. Concentrations <1 mg PO4-P/liter were common in the drainage water from all plots during this period while K concentrations varied between 1 and 12 mg/liter. Peak concentrations and discharge of fertilizer nutrients were shown to be a function of rainfall, irrigation, and timing of fertilizations. Deeply incorporated limestone applications into the subsoil tended to increase the NO3-N and decrease PO4-P discharged over that from deep tillage alone.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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