Long-term effects of single potassium fertilization on 137Cs levels in plants and fungi in a boreal forest ecosystem

► Effects of potassium fertilizer on 137Cs uptake by plants and fungi are investigated. ► 137Cs activity concentrations in forest plants decreased even within the first year. ► The most significant reduction occurred over the first 7-8 years. ► The reduction in fungi was less pronounced, but still statistically significant.