Radiocesium distribution caused by tillage inversion affects the soil-to-crop transfer factor and translocation in agroecosystems

This study reports the translocation of cesium-137 (Cs-137) into deep soil layers, and the Cs-137 transfer from soil to soybean in farmland under three tillage (no tillage, NT; rotary cultivation, RC; moldboard plow; MP) treatments and an undisturbed grassland (GL) at eight years after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on 11 March 2011 in Japan. Tillage influences the(137)Cs distribution in the 0-30 cm of soil; the distribution of(137)Cs in the soil was uniform under RC and MP treatments, while in the grassland, most Cs-137 was concentrated on the soil surface (0-2.5 cm). The center of vertical 137Cs radioactivity concentration (the thickness of the soil from surface which containing half of the Cs-137 inventory) in GL was 5.5 cm, which was shallower than that in farmland (9.5 cm in NT, 13.6 cm in RC and 15.2 cm in MP). Hence, the total translocation distance of 137Cs 8 years after FDNPP accident showed the following trend: GL (2.4 cm) < NT (7.0 cm) < RC (10.0 cm) < MP (12.3 cm). Meanwhile, a significant positive correlation was observed between Cs-137 radioactivity concentration and organic carbon and nitrogen content in the soil. However, the Cs-137 radioactivity concentration in soybean grains was negatively correlated with the center of vertical 137Cs radioactivity concentration but positively correlated with the ratio of exchangeable Cs-137 (ExCs) and K content in the soil. The ExCs/K and Cs-137 distributions in the soil were combined into a statistical model to predict the(137)Cs radioactivity concentration in soybean grain. The results revealed the magnitude of the impact of Cs-137 distribution on the Cs-137 transfer from soil to crop. The addition of the Cs-137 distribution dramatically improved the accuracy of the prediction model of & nbsp;Cs-137 radioactivity concentration in soybean.

Automated summary

This study investigates the transfer of Cs-137 in soil and its impact on the concentration of Cs-137 in soybeans after the Fukushima nuclear accident. The results demonstrate that tillage practices and soil properties play a significant role in the translocation of Cs-137 between soil and crops.