Using 137Cs and 210Pbex to assess soil redistribution at different temporal scales along with lithogenic radionuclides to evaluate contrasted watersheds in the Uruguayan Pampa grassland

•Cultivated watershed shows a higher erosion rate estimated by 137Cs.•Older cultivated areas show higher erosion estimated by 137Cs than by 210Pbxs.•Approximately 50 % reduction in soil loss from tillage to NTROT management.•No significant differences in recent soil erosion in both watersheds.•Mass activities of lithogenic radionuclides depend on soil type and erosion level.