Fig. 6
15N enrichment of the labeled and neighboring crop rows at four soil depths. The 15N enrichment measurements were performed on grain at harvest (a winter wheat in Exp. 1, b spring barley in Exp. 2, and c spring barley in Exp. 3) or on green tillers 25 days after labeling (d ryegrass in Exp. 4). The neighbor crop rows were 0.25 m or 0.50 m from the labeled crop rows. Different lowercase letters indicate significant differences among crop rows at P < 0.05. The furthest neighbor crop rows were only replicated once, and their statistical significance was ignored