02107naa a2200241 a 450000100080000000500110000800800410001910000200006024501210008026000090020152014040021065000130161465000160162765000240164365000130166765000190168065300110169970000180171070000300172870000200175870000150177877300720179314102292022-11-22       2008    bl uuuu     u00u1 u    #d1 aMCGRODDY, M. E.  aRetention of phosphorus in highly weathered soils under a lowland Amazonian forest ecosystem.h[electronic resource]  c2008  aThe low available phosphorus (P) pools typical of highly weathered tropical forest soils are thought to result from a combination of export of phosphorus via erosion and leaching as well as chemical reactions resulting in physically and chemically protected P compounds. Despite the low apparent P availability, these soils support some of the highest terrestrial net primary productivity globally. We followed different P fractions after P additions to two soil types, sandy loam and sandy clay, over 1 year in a lowland Amazonian forest. Of all the soil P fractions measured, only the NaHCO3 and NaOH extractable fractions showed a significant increase following P additions, and this occurred only in sandy clays (+ 56.9 ± 15.1 kg ha-1 and + 2.8 ± 1.5 kg ha-1, respectively). Our results indicate that intermediate rather than recalcitrant pools are the dominant fate of added P over an annual timescale even in fine-textured soils. Fine root and forest floor P pools increased more in the sandy loams following P additions suggesting a larger biotic P sink in these soils. Leaching of inorganic P from the surface soils was an unexpected and significant fate of added P in both soil types (9 ± 3% in the sandy loams, 2 ± 1% in the sandy clays). Significantly more of the added P was retained in the sandy clay soils than in the sandy loams (69 ± 20% versus 33 ± 7%) over the 1-year period.  aAmazonia  aEcossistema  aFertilidade do Solo  aFósforo  aSolo Florestal  aBrasil1 aSILVER, W. L.1 aOLIVEIRA JUNIOR, R. C. de1 aMELLO, W. Z. de1 aKELLER, M.  tJournal of geophysical Researchgv. 113, n. G4, p. 1-11, Dec. 2008.