Nutrient Status in Composts and Changes in Radioactive Cesium Following the Fukushima Daiichi Nuclear Power Plant Accident

Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, the forests in the Fukushima area were highly contaminated with radiocesium (137Cs and 134Cs). Therefore, there is a need to develop strategies for remediation of the contaminated forests. We assessed changes in radioactive cesium (134Cs and 137Cs) contamination and nutrient status in composts derived from wood chip, bamboo leaf and bamboo powder using rice bran and wheat meal as sub-materials. Changes in soil properties and Komatsuna (Brassica rapa var. perviridis) growth were also investigated due the application of composts and initial materials at 0, 2.5, 5 and 10 kg·m−2 input levels. Mixing of sub-materials significantly reduced the concentration of radioactive Cs and improved compost quality. The effectiveness of three composts on soil quality improvement varied depending on their types and rates of applications. Amendments of bamboo leaf composts at 10 kg·m−2 resulted in the significantly highest soil inorganic N, available P and exchangeable K contents. Amendments of final composts also enhanced Komatsuna growth. Furthermore, radioactive Cs contaminations of the Komatsuna plants grown in these composts were below 0.1 Bq·kg−1. This study may help to remediate the forests contaminated with radiocesium in the Fukushima area while improving the soil organic matter content to enhance soil sustainability