Spatial and temporal variation in N transfer in grass-white clover mixtures at three Northern European field sites

► N transfer and soil inorganic N uptake studied at three sites contrasting in climate and soil conditions. ► Short-term (3 weeks) N transfer from white clover to grass was higher in autumn than in spring and summer. ► The spatial extent of N transfer exceeded 50 cm for receiving grass on several occasions. ► Inter-species N transfer to neighboring plants indicate reuptake of N lost from plant roots. ► Indications of N transfer and N reuptake to occur in organic N form.