The aim of this study was to determine the available and slowly available potassium capacity of soil samples collected from the Kahramanmaraş plain. Slowly available potassium content was determined by the HCl extraction method. Slowly available potassium was found at between 3 and 46 mg 100 g-1 at a depth of 0-15 cm, 1 and 33 mg 100 g-1 at a depth of 15-30 cm and 1 and 25 mg 100 g-1 at a depth of 30-45 cm. Slowly available potassium content decreased along with soil depth. Available potassium content also decreased with soil depth. A significance correlation (0.1%) was found between available potassium and slowly available potassium. It was concluded that the slowly available potassium of soils could indicate the need of fertilisation in samples 11 and 12 in a short time, and in samples 2, 3, 4, 5, 6, 7, 8, 9, 13 and 14 in 5-15 years. Slowly available potassium was sufficient in samples 1 and 10. The insufficiency of the slowly available potassium of plain soils indicated that it might be useful to check the potassium content of the soil at certain intervals.

The aim of this study was to determine the available and slowly available potassium capacity of soil samples collected from the Kahramanmaraş plain. Slowly available potassium content was determined by the HCl extraction method. Slowly available potassium was found at between 3 and 46 mg 100 g-1 at a depth of 0-15 cm, 1 and 33 mg 100 g-1 at a depth of 15-30 cm and 1 and 25 mg 100 g-1 at a depth of 30-45 cm. Slowly available potassium content decreased along with soil depth. Available potassium content also decreased with soil depth. A significance correlation (0.1%) was found between available potassium and slowly available potassium. It was concluded that the slowly available potassium of soils could indicate the need of fertilisation in samples 11 and 12 in a short time, and in samples 2, 3, 4, 5, 6, 7, 8, 9, 13 and 14 in 5-15 years. Slowly available potassium was sufficient in samples 1 and 10. The insufficiency of the slowly available potassium of plain soils indicated that it might be useful to check the potassium content of the soil at certain intervals.