I've mentioned a study before showing increased yields in Blueberries, and research out of Texas has demonstrated cotton yield increases of 18% with improved pollinator habitat.
But Corn & Soybeans?
Iowa's largest commercial crops corn and soybeans don't rely on pollinators like many other crops. However, new research by Iowa State's Matt O'Neal suggests growing more bee-friendly habitats could prove to be a worthwhile goal for soybean growers looking to improve yield.
Read more http://cornandsoybeandigest.com/soybeans/can-bees-build-soybean-yields
"Three examples of earlier research include:
• A short-term Canadian study found bees’ presence was associated with much higher yields in food-grade soybeans.
• Australian researchers demonstrated yield increases of 10-40% in honey bee-pollinated soybeans, compared to self-pollinated beans.
• In 2005, a Brazilian research project compared soybean seed production with and without honey bee colonies by raising plants in cages, and reported 50% higher yields when bees were present."