Studies on soil phosphorus. I. A method for the partial fractionation of soil phosphorus
- 1 July 1950
- journal article
- research article
- Published by Cambridge University Press (CUP) in The Journal of Agricultural Science
- Vol. 40 (3) , 233-242
- https://doi.org/10.1017/s0021859600045895
Abstract
Ghani's method for the partial fractionation of soil phosphorus has been simplified. From results obtained with soils and representative phosphatic minerals it has been shown that successive single extractions with 2·5% acetic acid-l% 8-hydroxyquinoline and 0·1 N-sodium hydroxide gives a good fractionation of the phosphate compounds present.The relative effects of cupferron and 8-hydroxyquinoline as reagents for blocking the adsorption of phosphate were also investigated. Cupferron precipitated aluminium more completely than did 8-hydroxyquinoline at the pH used for the extraction. However, because of its instability and also because of indications that it may attack organic forms of phosphorus cupferron was considered to be of less value than 8-hydroxyquinoline in the fractionation of soil phosphorus.The recovery of phosphate added to soil, the reaction of which had been varied by the use of sulphur or calcium carbonate, was almost complete at all reactions used (pH 4·5–8·2) for amounts of phosphate up to the equivalent of 500 parts of PO4 per million parts of soil. The distribution of this added phosphate between the acid and alkali soluble fraction showed that in acid soils the phosphate tended to be fixed mainly by adsorption or as a basic ferric and aluminium phosphates, while at an alkaline reaction most of the fixation was due to precipitation by calcium.Keywords
This publication has 2 references indexed in Scilit:
- Extraction and Colorimetric Estimation of Certain Metals as Derivatives of 8-HydroxyquinolineIndustrial & Engineering Chemistry Analytical Edition, 1943
- Improvements in the deniges colorimetric method for phosphorus and arsenicIndustrial & Engineering Chemistry Analytical Edition, 1929