ISO-11263-1994.pdf

INTERNATIONAL STANDARD IS0 11263 First edition 1994-l 2-01 Soil quality - Determination of phosphorus - Spectrometric determination of phosphorus soluble in sodium hydrogen carbonate solution Qua/it d is the dilution factor of the soil extract (if required); “1 is the mass, in grams, of air-dried soil; m;, is the mass, in grams, of oven-dried soil. 7 Repeatability The repeatability of the determination of phosphorus soluble in sodium hydrogen carbonate solution carried out following colour development at room tempera- ture, or colour development after heating to a high temperature, shall satisfy the conditions given in table 2. Table 2 - ReDeatabilitv Phosphorus content mglkg Acceptable variation lOto25 25to 100 100 3 mg P/b 40 % of the value 15 mg P/kg 25 % of the value 6.5 Calculation The content of phosphorus soluble in sodium hydro- gen carbonate, in milligrams per kilogram of dried soil, is calculated using the following equation wp = PPkkS - 4) x 20d.m, As - A0 m, where PP is the phosphorus concentration, in milli- grams per litre, in the chosen standard solution (see table 1 I; AES is the absorbance of the soil extract; A, is the absorbance of the blank; AS is the absorbance of the chosen standard solution; 8 Test report The test report shall contain the following information: a) a reference to this International Standard; b) a reference to the method used; c) all information necessary for complete identifi- cation of the sample; d) the results of the determination in whole num- bers, in milligrams of phosphorus per kilogram, calculated on the basis of oven-dried soil; e) any details of operations not specified in this International Standard or which are regarded as optional, as well as any other factor which may have affected the results. Q IS0 IS0 11263:1994(E) Annex A (informative) Bibliography l BARROW, N.J. and SHAW, T.C. Sodium bicarbonate as an extractant for soil phosphate: II. Effect of varying the conditions of extraction on the amount of phosphate initially displaced and on the secondary adsorption (19761, Geoderma 16, pp. 109-l 23. 2 DUVAL, L. etude des conditions de validit& du dosage c&uleomolybdique de Iacide phospho- rique. Consequences pratiques (19631, Chim. Anal. 45, pp. 237-250. 3 GRIGG, J.L. The relationship between levels of soil phosphorus and responses to applied phosphorus in pasture topdressing trials (I 9721, N.Z. Journal of Agricultural Research 15, pp. 643-652. 4 OLSEN, R., COLE, C.V., WATANABE, F.S. and DEAN, L.A. Estimation of available phosphorus in soils by extraction with sodium bicarbonate (19541, U.S. Dept. of Agric. Cir. 939. 5 STONE, B. Effect of temperature and shaking rate on sodium bicarbonate soluble phosphorus (1971). Soil Res. Branch, Canada, Dept. of Agric., CEF, Ottawa, Ontario, Contr. No. 357. 5 -,-,- IS0 11263:1994(E) ICS 13.080.00 Descriptors: sok, quality, so11 testing, chemical analysis, determlnatlon of content, phosphorus, spectrophotometnc analysis Pnce based on 5 pages -,-,-