Fig. 1. Dissolution of Kanchanaburi rock phosphate (KRP) as represented by the differences in NaOH-extractable-P, Mitscherlich fit curve and changes of soil pH between KRP-amended (KRP 500 mg P kg^–1) and KRP unamended soils (KRP 0 mg P kg^–1) in acid sulfate soils initially and after amending with KRP.