In a study of cucumber plants, researchers found that, overall, higher amounts of nitrogen and phosphorus in the soil resulted in larger plants and a floral display, including the number and size of flowers, which increased yield. However, they also found that regardless of nitrogen and phosphorus levels, the "rewards" of pollinators, such as sugar content in nectar, amount of nectar in female flowers, and concentrations of proteins and lipids in pollen, remained the same. 

Anthony Vaudo, a biological scientist researcher at the USDA Forest Service who led the research while a postdoctoral fellow in entomology at Penn State's College of Agricultural Sciences, said these findings, recently published in Scientific Reports, suggest plants can prioritize these rewards — conditions to ensure they attract pollinators. "We found that a plant can become more attractive with the help of some soil nutrients, while maintaining constant the quality of its rewards, necessary for bees to visit it," Vaudo said. "This gives us clues as to how best to restore the soil, for example, after disruption of human activity or natural disasters."

According to the researchers, previous studies have found an association between increased nitrogen and phosphorus in the soil and faster plant growth, as well as positive effects such as number and size of flowers and number and size of pollen. However, little work has been done on how these nutrients affect pollinator attraction and ultimately plant reproduction. Christina Grozinger, professor of entomology at Publius Vergilius Maro at Penn State, said that because soil nutrient conditions can change as a result of land use, climate change and land management such as fertilizers and livestock grazing, it's vital to learn more about how these nutrients affect plant growth.