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This article in SSSAJ

  1. Vol. 65 No. 4, p. 1293-1302
    Received: Aug 23, 1999

    * Corresponding author(s): mwalbrid@osf1.gmu.edu
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Phosphorus Availability in an Artificially Flooded Southeastern Floodplain Forest Soil

  1. R. B. Wrighta,
  2. B. G. Lockabyb and
  3. M. R. Walbridge *c
  1. a Environmental Science and Public Policy Program, MS 5F2, George Mason Univ., Fairfax, VA 22030-4444
    b School of Forestry, Auburn Univ., Auburn Univ., AL 36849
    c Environmental Science and Public Policy Program, MS 5F2, George Mason University, Fairfax, VA 22030-4444


Studies of how flooding affects P availability in natural floodplains are rare. We examined the effects of artificial flooding on P availability in a Georgia floodplain forest. We hypothesized that P availability would increase with flooding, because of the flooding-induced solubilization of phosphate minerals. Field mesocosms (n = 4 per treatment) were flooded with river water according to one of four treatments over ∼6 mo: (i) continuously flooded; (ii) flooded for 3 mo and then drained; (iii) flooded for 2 mo, drained for 1 mo, and repeated; and (iv) nonflooded control. Two additional sets of 3-mo flooded–drained mesocosms (n = 4 per set) received added P or N (1 and 10 mg L−1, respectively) with flooding. Soils were collected monthly from both inside and outside of the mesocosms and analyzed by Hedley fractionation; anion-exchange resins (AER) were used to estimate P availability in situ. As indexed by daily supply to AER, P availability was significantly greater in flooded versus control soils, and decreased significantly following drainage, in all treatments at some time during the study. Total P supply to AER was significantly greater in flooded versus control mesocosms regardless of treatment. No significant changes were observed in Fe/Al phosphate fractions. Microbial P was significantly lower in flooded versus control mesocosms during the first 3 mo of flooding and decreased significantly over time in two treatments. In this natural floodplain, biological processes are a more probable explanation for flooding-induced increases in P availability than solubilization of mineral phosphates.

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Copyright © 2001. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.65:1293–1302.