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Volume 29, Issue 6 p. 677-678
Division S-2—Soil Chemistry

Test of an Ascorbic Acid Method for Determining Phosphorus in Water and NaHCO3 Extracts from Soil

F. S. WatanabeS. R. Olsen

S. R. Olsen

Research Soil Scientists, USDA, Ft. Collins, Colo.

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First published: 01 November 1965
Citations: 1,620

Contribution from Northern Plains Branch, Soil and Water Conservation Research Division, ARS, USDA, in cooperation with the Colorado Agr. Exp. Sta. Scientific Journal Series 1000.


Murphy and Riley proposed use of a single reagent for determining P. The method was found to be accurate for determining P in soil extracts. This method is based on reduction of the ammonium molybdiphosphate complex by ascorbic acid in the presence of antimony. The color produced is stable for 24 hours. It is less subject to interfering substances than are methods involving reduction by SnCl2.