ISSN:
1365-2389
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
The influence of water: soil ratio (w: s) on phosphorus fractions was studied in Andisols and Andic soils. Phosphorus was fractionated in 0.45-μm filtered water extracts, and pH, monomeric Al and dissolved organic carbon (DOC) were determined. Speciation of dialysed extracts was also studied. Increasing w: s from 2.5 to 75 resulted in a release of dissolved reactive phosphorus (DRP), while DOC decreased significantly and pH increased moderately. For the 29 samples studied desorbed DRP =K (w: s)β, where β represents a P buffering term and ranged from 1 to 1.26 for DRP (mg kg−1). On dialysis, we observed a uniform partition between dialysable (DP) and non-dialysable P (NDP) which was explained by the corresponding difference in DOC; these results were consistent with the existence of soluble P-Al-fulvic complexes. Study of solubility diagrams for determining solid-phase controls on P activities in the extracts suggested that dissolution of Al-phosphates could explain most of P release to water as free orthophosphate. Both this mechanism and organic P partition between solid and solution soil phases may be considered to reflect the main sources of P in Andisols: Al-phosphate and organic-Al-P complexes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2389.1996.tb01412.x
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