Mulching as a Countermeasure for Crop Contamination within the 30 km Zone of Chernobyl Nuclear Power Plant

The effect of mulch soil cover on crop contamination by 137Cs was studied within the 30 km zone of Chernobyl Nuclear Power Plant. Experiments were performed with oats (Avena sativa) over a three year period. In 1992 soil surface was covered by a plastic net. In 1993 two straw mulch treatments were applied at a dose rate of 200 g m-2 using 137Cs contaminated and clean straw, respectively. A similar mulch treatment was applied in 1994, and two mulch doses of clean straw were tested (200 and 50 g m-2). Protection of the soil with a plastic net significantly increased crop yield and reduced crop contamination (by about 30%). When clean straw was used as a mulch layer, a significant decrease of about 30−40% in 137Cs activity concentration was observed. Mulching with 137Cs contaminated straw did not reduce crop contamination, probably due to an increase in soil available 137Cs released from the contaminated mulch. Mulching has been shown to be an effective treatment both for reducing 137Cs plant contamination and improving crop yield. Therefore, it can be considered as a potential countermeasure in a post-accident situation.