Chemical properties of upland peats influencing the retention of phosphate and potassium ions

Summary Peat samples representing depths of 0–15 cm and 15–30 cm were obtained from 11 upland sites in southern Scotland. Their pH, ash content, cation exchange capacity, phosphate sorption index and contents of 0.1 m hydrochloric acid‐extractable iron and aluminium were determined as indicators of the extent to which phosphate and potassium ions would be retained following afforestation and application of fertilizers to these sites. In all soils cation exchange capacities were considerably larger than the quantity of potassium normally applied as fertilizer. Phosphate sorption indices were closely related to the content of extractable iron and aluminium in the peat samples. When expressed on a volume basis, the indices were low compared with those published for mineral soils, and some peats appeared to have almost no capacity to sorb phosphate ions from solution.