Effect of application timing of potassium fertilizer on root uptake of 137Cs in brown rice

We investigated the optimal timing and quantity of K to reduce radiocesium in brown rice. The concentration of 137Cs in brown rice was reduced from 32 Bq kg−1 without K fertilizer to 2.0 Bq kg−1 with 16 g m−2 of basal K. The concentration of exchangeable 137Cs in the soil decreased from 234 to 25 Bq kg−1 with increasing application of K fertilizer from 0 to 57 g m−2. Hence, heavy application of K fertilizer in the early growing period can decrease the uptake of 137Cs by rice plants and the concentration of exchangeable 137Cs in the soil.