Commodity markets have many farmers converting CRP and other grassland acres back into production. When planting soybeans on newly converted acres, Matt Hubsch, Senior Agronomist with Legend Seeds, encourages farmers to consider double-inoculating the soil.
"Last growing season I looked at several fields of soybeans which were planted into CRP ground and were not thriving. When I pulled up the plants to look at their roots, the roots didn’t have any nodules – or very few," says Hubsch, of the fields he discovered had only received one inoculation.
Soybeans need the bacterium rhizobium for proper nodulation. Nodulation allows the plant to convert N2 from the atmosphere into usable nitrogen. This bacterium is present in fields that have raised soybeans within the last three planting cycles.
"Rhizobium is important for nodulation," Hubsch says. "To ensure its availability in soils that haven’t raised soybeans before, university researchers encourage producers to double-inoculate at planting."

When the microbe is not available, the plants will show signs of nitrogen deficiency which, according to Hubsch, ultimately leads to yield loss.
"The ultimate goal is for soybeans to get 75 percent of their nitrogen needs from the air – which depends on proper nodulation," Hubsch says.
For fields that are converted from grassland or have not raised soybeans in the last three years, Hubsch recommends a dual mode of inoculation – using a dry and liquid inoculant.
Even in fields where soybeans are a part of the cropping rotation, Hubsch encourages producers to apply a single inoculation at planting to ensure proper populations of rhizobium are available.
"Because Rhizobium is an aerobic, living microbe, excess moisture may kill it off. By reintroducing rhizobium every time we rotate back to soybeans, we’re ensure the plants have what they need for proper nodulation," Hubsch says.