Kosuke Noborio, School of Agriculture, Meiji University, Kawasaki-shi, Kanagawa, JAPAN, Yuki Ito, Tama-ku, Meiji University, Kawasaki, Kanagawa, JAPAN, Yuki Takagi, Meiji University, Kawasaki, JAPAN, Ryuta Honda, School of Agriculture, Meiji University, Kawasaki, Japan, Hiroshi Takesakko, Agricultural Chemistry, Meiji University, Kawasaki, Japan, Kiyoshi Ozawa, Kurokawa Field Science Center, Meiji University, Asao-ku, Kawasaki, Japan and Eiji Kita, Routrek Networks Inc., Kawasaki, Japan
In Fukushima, Japan, where soils were contaminated by radiocesium (Cs134+Cs137) due to the accident of the Fukushima Daiichi Nuclear Power Plant in 2011, farmlands were decontaminated by scraping a top 5 cm fertile soil layer containing most of fallout radiocesium as well. Decontaminated farmlands received a 5–10 cm thick rediocesium-free yet less-fertile sandy soil. We applied a cloud-based fertigation system to grow vegetables in the less-fertile sandy soil mixed with the original soil in a greenhouse. The radiocesium concentration in the sandy soil that we planted vegetables was 1,448 Bq/kg whereas that in a contaminated soil as a control was 30,351 Bq/kg. The radiocesium concentration of tomato grown in the decontaminated soil ranged between 0.3 and 0.8 Bq/kg, meaning the transfer factor (f=radiocesium concentration in vegitable/radiocesium concentration in soil) ranged between 0.0002 and 0.0006, whereas that of bell pepper ranged between 5.4 and 7.2 Bq/kg (f=0.004-0.005). The radiocesium concentration of spinach ranged between 6.2 and 9.0 Bq/kg (f=0.0042-0.0063), for a normal K application, but the radiocesium concentration decreased to 2.2 Bq/kg (f=0.0015) for a doubled K application. Spinach grown in the high radiocecium concentration soil contained 139.3 Bq/kg for the normal K application (f=0.0046) whereas the doubled K application reduced the radiocesium to 77.0 Bq/kg (f=0.0025). The transfer factors of spinach grown in either radiocesium concentration soil were similar although the K addition might be less effective to reduce a transfer rate in the high concentration of radiocesium soil.