01424naa a2200181 a 450000100080000000500110000800800410001910000170006024500830007726000090016052009450016965000130111465000140112765300190114165300100116070000190117077300530118920081062015-02-19       1958    bl ---       0--  u    #d1 aCHANG, S. C.  aSoil phosphorus fractions in some representative soils.h[electronic resource]  c1958  aThe distribution of soil inorganic phosphorus in soils was found to measure the degree of chemical weathering, the chemical weathering sequence being calcium phosphate, aluminium phosphate, iron phosphate, and occluded phosphate. The latter category includes reductant soluble iron phosphate and aluminium-iron phosphate occluded in iron oxides. For example, three horizons of one chernozem profile, a Dark Brown soil, and the calcareous C1 horizon of a Grey-Brown Podzolic soil contained  68-95 per cent. Of their inorganic phosphurus in the form of calcium phosphate, the other forms decreasing exponentially in the sequence. The inorganic phosphurus of two Latosols increased exponentially in the order calcium phosphate(I%), aluminium phosphate (0-3%), iron phosphate (10-13%), and occluded (reductant soluble) phosphate (66-78%). Three samples of podzolized soils contained intermediate, sigmoidal distributions of the four phosphates.  aFósforo  aNutriente  aFertilização  aSolos1 aJACKSON, M. L.  tJournal of Soil Sciencegv. 9, p. 109-119, 1958.