Efficacy of cover crops for pollinator habitat provision and weed suppression

Pollinator declines have been documented globally, but little information is available about native bee ecology in Midwestern US agriculture. This project seeks to optimize pollinator support and weed suppression in a 3-year crop rotation with a fallow growing season. During fallow, one of five cover crop treatments (T1: crimson, red, and ladino clover and Bob oats [Trifolium incarnatum, T. pratense, T. repens, Avena sativa]; T2: crimson clover and oats; T3: red clover and oats; T4: ladino clover and oats; T5: no cover crop; T6/control: winter wheat [Triticum aestivum]) was seeded in one-half of 25 agricultural fields, while wheat was left unharvested in the other half as a comparison. Treatments that provide season-long floral resources support the greatest bee diversity and abundance (T1), and treatments with red clover support declining Bombus species (T1 and T3). Late-season floral resources may be important, yet limited (T1 and T4), and some species of agricultural weeds provide fl...