Soybeans greatly benefit from nitrogen-fixing bacteria, which reduces the need for fertilizer, and a new study shows that gene-edited bacteria can supply the equivalent of 35 pounds of nitrogen from the air during early corn growth as well. 

Agricultural scientists tested products from Pivot Bio called PROVEN and PROVEN 40, which includes one and two species of soil bacteria, respectively, that turn atmospheric nitrogen into plant-available forms. An edited gene involved in nitrogen fixation makes more of it available so more of it at planting means the bacteria colonize plant roots.

They applied at planting during three field seasons, including nitrogen fertilizer at 0, 40, 80, 120, or 200 pounds per acre. Then they measured nitrogen in plant tissues at the V8 stage (eight fully-collared leaves) and at R1 (silk emergence) then grain yield at the end of each season.

Isotopic nitrogen showed that additional nitrogen uptake in the inoculated plots was from the atmosphere, supplementing the soil and fertilizer supply, and across all nitrogen fertilizer rates, the inoculant increased corn vegetative growth, nitrogen accumulation, kernel number, and yield by 2 bushels per acre on average. At the moderate nitrogen rates, yield went up by 4 bushels per acre. This was equivalent to 10-35 pounds of nitrogen per acre of fertilizer. 


Gene-edited bacterial inoculant supplied up to 35 pounds of nitrogen to corn during early growth. Credit: University of Illinois Urbana-Champaign

“The overall yield response was positive, but modest. The 35 pounds of fertilizer equivalent during early growth was down to about 10 by season’s end,” said senior study author Fred Below, professor in crop sciences at the University of Illinois. “Clearly, there is still a need to fertilize.”

Yet as part of a decades-long plan to boost food yields with even fewer chemicals than the conventional process uses now, this is an important waypoint. And could be used now.

“Every farm has areas of the field where the soil does not provide enough nitrogen or the fertilizer was lost or unavailable, so a microbial inoculant to provide a third source of nitrogen could help,” said co-author and research assistant professor Connor Sible. “Sometimes corn fields receive ‘insurance nitrogen’ where an extra 20 pounds is supplied in case it is a year prone to nitrogen loss. Perhaps a nitrogen-fixing inoculant can reduce the need for those extra 20 pounds, and this could have a large impact when summed across all Corn Belt acres.”