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.