If corn has ever envied soybeans for their partnership with nitrogen-fixing bacteria, new advances in gene editing could change the game. A recent investigation from the University of Illinois Urbana-Champaign indicates that gene-edited bacteria can provide around 35 pounds of nitrogen from the atmosphere during the early stages of corn growth, potentially lowering the crop’s dependence on nitrogen fertilizers.
“Eliminating synthetic nitrogen completely would be remarkable. Perhaps in a century, we will discover the right microbes and genetic adjustments to get nearer to that goal, but we aren’t there yet. Yet, we must begin our journey, and this research shows that there is potential for nitrogen fixation in corn,” remarked Connor Sible, co-author and research assistant professor in the Department of Crop Sciences at the University of Illinois.
Sible and his team examined products from Pivot Bio named PROVEN and PROVEN® 40, which consist of one or two species of soil bacteria that can convert atmospheric nitrogen into forms available for plants. The gene-edited variants enhance the function of a crucial gene associated with nitrogen fixation, increasing the amount accessible for plants. When these bacteria are introduced at planting time, they colonize the roots, providing nutrients right where they are needed the most.
The company asserts that biologically-fixed nitrogen could potentially replace as much as 40 pounds of fertilizer nitrogen per acre.
“There is a scarcity of peer-reviewed data to back this assertion. Additionally, there hasn’t been any research evaluating the extent of nitrogen replacement and the timing of nitrogen accumulation during the growth cycle,” noted Logan Woodward, who conducted the study as a doctoral student at Illinois. “Our aim was to address these information gaps.”
The researchers applied the products during planting across three different seasons, utilizing standard practices for growing corn, which included nitrogen fertilizer at varying rates of 0, 40, 80, 120, or 200 pounds per acre. They subsequently measured nitrogen content in plant tissues at the V8 stage (eight fully developed leaves) and at R1 (when silks appear), along with grain yield at the end of each growing season. Analysis of the stable isotopic nitrogen revealed that the additional nitrogen in the inoculated plots originated from the atmosphere, supporting the supply from soil and fertilizer.
The findings demonstrated that, irrespective of nitrogen fertilizer rates, the inoculant led to enhanced vegetative growth, nitrogen accumulation, kernel count, and an average yield increase of 2 bushels per acre. For moderate nitrogen application rates, the yield rose by 4 bushels per acre, which corresponds to 10-35 pounds of nitrogen per acre from fertilizer.
“The general yield increase was favorable but modest. The 35 pounds of fertilizer equivalent during the early growth phase diminished to about 10 by season’s conclusion,” stated Fred Below, the senior author of the study and professor in crop sciences. “It is clear that fertilization is still necessary. A sufficient amount of nitrogen is essential for nurturing a robust plant, as a healthy plant can generate the root sugars required to sustain the microbes. Lack of nitrogen means the plant can’t thrive nor support the inoculated microbes, greatly reducing efficacy in the absence of some fertilizer nitrogen.”
While current products cannot fully replace synthetic fertilizers, the research team believes the technology has promise and hopes it can be enhanced to yield even greater outcomes. Nevertheless, these products may still be beneficial in certain situations today.
“Every farm has sections where the soil fails to supply enough nitrogen or where fertilizer is lost or inaccessible, so a microbial inoculant could introduce a third nitrogen source,” stated Sible. “Occasionally, corn fields receive ‘insurance nitrogen,’ where an additional 20 pounds is added as a precaution in years with potential nitrogen loss. Perhaps a nitrogen-fixing inoculant could lessen the necessity for those extra 20 pounds, which could significantly impact when considered across all acres in the Corn Belt.”
