Changes in extractable sulpher and potassium levels in soil due to oven drying and storage

Abstract

Appreciable increases in 'available' sulphur were noted for six soils from South Gippsland after oven drying at 40°C. Oven dried soils stored at room temperature or 3°C for periods of up to 12 months showed significant increases in sulphur extractable with calcium phosphate but not in sulphur levels extractable with charcoal plus calcium phosphate. Application of toluene as a bacteriostatic agent failed to stop increases in levels of sulphur extractable with calcium phosphate, although the magnitude of the increases was reduced. No significant increase of 'available' potassium due to oven drying was noted, and the period of storage had no noticeable effects on 'available' potassium levels. Therefore soil samples may be stored for periods of at least 12 months prior to analysis.