Available Sulphur Determination in Soil

Turbiditmetric Procedure Monocalcium Phosphate Extratable S Ensminger, 1954). Principle 

Sulphur (S) occurs in soils usually as sulphites, sulphates, sulphides and in organic compoimds. However, the most accessible form is sulphate (SO ). The turbidimetric procedure is widely used in the estimation of available S in the soil due to its rapidity. However, erroneous results are obtained in case the soil is rich in organic matter. Soil is shaken with a solution of monocalcium phosphate, containing 500 ppm P. The phosphate ions displaces the adsorbed sulphate. The calcium ions depresses the extraction of soil organic matter, thus eliminating contamination from extractable organic S. The method extract soluble plus a fraction of adsorbed The filtrate is then analysed for S by the turbidimetric procedure. In this method 

Weight of soil taken Volume of extractant added 

Second dilution Thus total dilution 

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