Transfer of radiocaesium from soils to crops as influenced by soil type, ploughing and potassium fertilization. Data from long term post-Chernobyl field experiments in Russia and Sweden

The effects of various remedial measures on the crop uptake of radiocaesium have been studied in long term field experiments on different soil types in Chernobyl fallout areas in Russia and Sweden during 1987-1992. Various potassium fertilization regimes and ploughing up the contaminated grassland were included in the experiments. The 137Cs fallout density at the experimental sites as determined by the soil sampling varied between ca 0.2 MBq per m2 (Gavle area, Sweden) and ca 1.3 MBq per m2 (Novisibkov area, Russia). Soil types studied were sandy (Russia and Sweden), peat (Sweden) and black (Russia). Very apparent effects of the various treatments were obtained in the most of experiments. Potassium fertilization of the contaminated grassland in amounts of 100-250 kg per ha usually reduced the transfer factor soil-grass by 20-50% as compared with the unfertilized plots. After ploughing up the contaminated grassland a reduction of the transfer factors by a value of 10 or more was obtained. The effect of establishing a new grassland combined with potassium fertilization leads to reduction factors of 15-20 or more. The transfer factor and the effects of the various treatments decreased in the order: peat soils>sandy soils>black soils. (author)