Pollinating insects can help soybean yields

AMES, Iowa – A new study indicates that insects like honey bees in many cases can do a better job of pollinating soybeans than the plants can do on their own.

The findings suggest growing soybeans near pollinator habitat might lead to better yields, said Lisa Schulte Moore, a professor of natural resource ecology and management at Iowa State University and a co-author of the study. Previous research has shown incorporating pollinator habitat into soybean production could lead to a number of environmental benefits, but the new paper shows how pollinator habitat may also improve production as well.

The paper resulted from an international collaboration by five researchers and was published in the peer-reviewed academic journal Trends in Ecology and Evolution.

The researchers conducted a survey and analysis of 16 previous studies from across the globe that looked at the impact pollinating insects have on soybean production. The team combined and synthesized the data from the previous studies and found wild bees and honey bees can improve soybean yields upward of 20% when they help to pollinate the soybean plants. The study compared these results to improvements in crop genetic and management factors, which ranged between 8 and 15%.

Schulte Moore has conducted previous research as part of the ISU Prairie STRIPS team showing that planting sections of pollinator habitat, such as prairie grasses and wild flowers, among agricultural fields creates biodiversity and slows nutrient runoff from the soil, among other environmental benefits. The new study suggests prairie strips might also strengthen production by attracting insects that can then pollinate nearby soybean plants.

“This is another piece of the puzzle that suggests the trade-off between crop production and ecosystem services is not as large as many people think,” Schulte Moore said. “There might be really nice synergies, especially in soybeans.”

Lead author Lucas Garibaldi, professor and director at the Institute for Research in Natural Resources, Agroecology and Rural Development at the Universidad Nacional de Rio Negro in Argentina, said, “Soybeans are one of the most important crops worldwide. Despite the potential for yield improvement through animal pollination, cultivation practices commonly ignore pollinators. Creating pollinator habitats and restoring biodiversity within agricultural landscapes can increase soybean productivity and provide multiple other benefits to society.”

Most soybean varieties are bred to be self-pollinating. That is, the pollen produced by a soybean plant’s flower fertilizes the pistil, or the ovule-producing organ, of the same flower. Pollinating insects can improve both pollination and cross-pollination, which is known to improve seed set, or the number of seeds a plant produces per seed pod.

“While our results show how managing for pollination and pollinator habitat can benefit soy, much research across the world shows that diversifying farm fields with small habitat patches can improve production and profits for a whole array of crops, by improving crop pollination and pest control and reducing pesticide use,” said Claire Kremen, President’s Excellence Chair In Biodiversity at the University of British Columbia and co-author of the study.

The 16 studies reviewed by the research team did not include any results from Iowa, Schulte Moore said. So she and fellow ISU soybean and pollinator researchers hope to gather Iowa-specific soybean data to test how pollinating insects affect yields. Schulte Moore said converting marginal acres that don’t usually turn a profit for farmers due to poor soil or hydrological conditions to pollinator habitat might make sense, particularly if doing so boosts the yields in surrounding acres.

“Here in Iowa, as we look at our agricultural landscapes, there could be opportunities where gains in production and gains in ecosystem services reinforce one another, rather than act as trade-offs,” she said. “To get there, we have to look further at data from Iowa fields.”