The potential for Nitrogen-fixing crops to deliver foraging resources for insect pollinators

There is growing concern insect pollinator declines will adversely influence global food security. Nitrogen-fixing crops, introduced as an Ecological Focus Area (EFA) in the 2014 CAP reform, provide nectar and pollen resources for pollinators. N-fixing crops therefore have the potential to promote pollinators in intensive arable landscapes. This research explores a range of N-fixing crops when grown as either straight crops or mixtures and determines their value to bees (i.e. bumblebees and honeybees). The number of bees visiting N-fixing crops showed clear differences that were related to phenological differences in flowering period and value of foraging resources (i.e. nectar and pollen). Crimson clover, red clover and mixtures containing these species were particularly profitable. Complementing economically viable species that flower early in the season (e.g. field beans) with species that provide high quality forage later in the season (e.g. crimson and red clover) has the potential to maximise benefits derived from N-fixing EFAs.