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Changes in Water‐extractability of Soil Inorganic Phosphate Induced by Sodium Saturation
Author(s) -
Sharpley A. N.,
Curtin D.,
Syers J. K.
Publication year - 1988
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1988.03615995005200030007x
Subject(s) - soil water , chemistry , distilled water , saturation (graph theory) , phosphate , sodium , environmental chemistry , population , extraction (chemistry) , water extraction , soil science , geology , chromatography , demography , mathematics , organic chemistry , combinatorics , sociology
The effect of replacing indigenous exchangeable cations with Na on the subsequent release of inorganic phosphate (P) from 34 USDA‐SCS benchmark soils representing nine soil orders was investigated by sequential extraction with distilled water. Sodium saturation substantially increased the water extractability of P regardless of whether Ca‐P or sorbed P was the predominant form of inorganic P in the soil. On average, Na‐saturated soils released about 2.5 times more P than the untreated soils. Sequential chemical extractions were used to identify the sources of P extracted. In soils that had not been Na saturated, water‐extractable P appeared to originate largely from the NaHCO 3 ‐extractable fraction. The additional P released following Na saturation was accounted for by a disappearance of Ca‐P compounds (HCl‐extractable) in soils where such entities were present or a decrease in the sorbed‐P fraction extracted by NaOH. The results indicate that the distribution of P between solid and solution phases is strongly dependent on the nature of the exchangeable cation population. These results have important implications to soil fertility and P availability in irrigated soils influenced by Na.