Fig. 4.

Percentage of nitrogen derived from the atmosphere (%Ndfa) in lupine, clover, and vetch grown as monocrops (white bars) or in mixtures (grey bars) with rapeseed (R-Lupine, R-Clover and R-Vetch). Vertical bars indicate ± S.E. (n = 5). * and ** indicate significant differences between monocrops and mixtures, with p < 0.05 and p < 0.01, respectively. Insert indicates δ¹⁵N values (‰) of legumes grown in monocrops (Lupine, Clover, Vetch) or in mixture with rapeseed (R-Lupine, R-Clover, R-Vetch) and δ¹⁵N of rapeseed grown in monocrops with one (R) or two (RR) plants per pot or in mixtures with legumes (R-Lupine, R-Clover and R-Vetch). Each value represents the mean ± S.E. for n = 5.