AS 4969.5-2008

This Standard specifies a method for the determination of peroxide sulfur (SP), calcium (CaP) and magnesium (MgP) in acid sulfate soil after hydrogen peroxide digestion and the determination of pHOX, and TPA and ANCE in AS 4969.3.NOTES: 1 This method recovers soluble and exchangeable sulfate, sulfate from gypsum, sulfate formed by oxidation of sulfide, sulfur released by the breakdown of organic matter as well as, variable amounts of sulfate from iron and aluminium sulfate minerals or compounds. Sulfate from jarosite and natrojarosite is not appreciably recovered. Methods to determine the residual sulfur held in these iron hydroxy-sulfate minerals are detailed in AS 4969.6 and AS 4969.11.2 The peroxide extraction procedure recovers soluble and exchangeable calcium and magnesium, and calcium from gypsum. Calcium and/or magnesium released by the acid dissolution of carbonate, oxide or hydroxide minerals are also recovered.3 The peroxide sulfur (SP) measurement can be used in combination with KCl extractable sulfur (SKCl, AS 4969.4) to calculate the peroxide oxidizable sulfur (SPOS, AS 4969.10). 4 The peroxide calcium (CaP) and magnesium (MgP) can be used in combination with KCl extractable calcium (CaKCl) and magnesium (MgKCl) (AS 4969.4) to determine ‘reacted’ calcium (CaA) and magnesium (MgA) (AS 4969.10).5 The residual acid soluble sulfur (SRAS) (AS 4969.6) can be determined on the entire soil residue following measurement of SP.

First published as AS 4969.5-2008.Reconfirmed 2018. First published as AS 4969.5-2008.