Samples of vegetation and faeces from heavily grazed pastures are likely to be contaminated with soil to some extent. The determination of total potassium on these samples will result in low recoveries if a wet oxidation procedure normally used for vegetation analysis is employed. However, data are presented which show that for the sites studied satisfactory recoveries of total potassium are obtained following a sulphuric acid‐hydrogen peroxide digestion, providing the ash content of the sample does not exceed 25%. For ash contents greater than 25%, alkaline fusion or hydrofluoric/perchloric acid decomposition procedures are required to obtain full recovery.