Effects of potassium fertilization on cesium-133 absorption by persimmon trees

In 2011, the Fukushima Daiichi Nuclear Power Station accident released radioactive materials, such as cesium (Cs), into the atmosphere and dropped onto agricultural land soil. Reducing radioactive Cs absorption from the soil is important for crop production. Therefore, persimmons were cultivated in pots with different amounts of potassium (K) fertilizer (+0 g, +20 g (standard level), and +40 g of K sulfate/pot), and the concentration of 133Cs in leaves and fruits was investigated. Additionally, the effects of phlogopite (materials expected to enhance K availability and radioactive Cs fixation in the soil) were investigated. K fertilization increased the exchangeable K concentration in the soil, and as the investigation continued, a significant difference in the K concentration in the leaves was observed. From the beginning of the 133Cs measurement, the 133Cs concentration in the leaves and fruits was significantly higher in the treatment without K fertilization. When the exchangeable potassium concentration in the soil was approximately 200 mg K2O kg-1 or less, the 133Cs concentration in the leaves tended to increase sharply. This suggests that controlling the Cs concentration in persimmon plants is possible by maintaining the exchangeable K concentration in the soil through K fertilization.