Continuous nitrogen fertilization retards the vertical migration of Fukushima nuclear accident-derived cesium-137 in apple orchard soil.

We monitored the levels of cesium-137 (Cs) in the soils of five orchards for six years following the Fukushima Daiichi Nuclear Power Plant accident on 11 March 2011 and found that the vertical distribution of accident-derived Cs varied significantly among the orchards with varying land-use and fertilizer management. Based on these results, this study evaluated how nitrogen (N) fertilizer management may have affected the vertical migration of Cs in the orchard soils. We selected an experimental orchard producing 'Jonathan' apples, where a long-term N-fertilizer trial has continued since 1973, with an N-fertilized plot (N plot; N added at 20 g m y) and a non-fertilized plot (0 N plot).