Phosphorus release from soils upon exposure to ultra‐violet light

Abstract

Available phosphorus (P) is often low in acid soils either due to its adsorption or precipitation by iron (Fe) oxides and hydroxides. Ultra‐violet (UV) light can induce the release of P from Fe(III)‐P compounds though the photo‐reduction process. Soils collected from a permanent timothy (Phleum pratense) pasture, subjected to manure applications at different rates and times of the year, were irradiated at different UV‐B strengths. No significant difference was obtained in the release of soluble reactive P (SRP) from soils irradiated at higher strength (45 mw^‐1 m^‐2) or lower strength (16 mw ^‐1 m^‐2) of UV‐B. The increase in SRP after UV irradiation, however, was highest in soils from unamended subplots followed by subplots amended with manure in spring and summer. This study showed that sunlight could play a significant role in maintaining a bioavailable P pool in soils. Moreover, the study hypothesized that an application of manure to a timothy pasture in the summer might reduce P loss to runoff and help to utilize native soil P.

Notes

Corresponding author (present address: Soil and Water Science Department, University of Florida, P.O. Box 110510, Gainesville, FL 32611).