1. Figure 9. Under conditions of higher soil nitrogen availability, grasses (or other non-legumes) may dominate the cover crop stand. Black indicates nitrogen from soil, gray indicates nitrogen from fixation. In 1-2, we again see that as soil nitrogen increases, the legumes planted in monocultures capture more soil nitrogen and the proportion of fixed nitrogen declines. 3) If soil nitrogen availability is very high, the grass will grow very quickly and legume growth will be suppressed. The proportion of nitrogen fixed will be greater than in the monoculture, but the total amount of nitrogen fixed will be reduced because the legume biomass is much smaller.