A recent study from the University of Illinois Urbana-Champaign sheds light on the limited benefits of nitrogen fertilizer for modern high-yielding soybeans. Contrary to popular belief, the research suggests that the natural partnership between soybeans and nitrogen-fixing bacteria is sufficient to meet the crop’s nitrogen needs, even with increasing yield potential.
The Soybean-Bacteria Symbiosis
Appendix: A symbiosis with bacteria that infects soybean roots Relations between the two are of course mutual,:) as the bacteria do this conversion on atmospheric nitrogen to form which the plant can directly utilize and get its nitrogen from!
This symbiotic relationship, in combination with the nitrogen from soil, has historically been considered adequate source for the need of the plant for nitrogen. As soybean yields have risen steadily over time, though, other researchers and farmers began to wonder if the natural system in Illinois was enough to handle those higher demands for nitrogen.
Putting Nitrogen Fertilizer to the Test
In this study, researchers with the University of Illinois Urbana-Champaign look to answer this question by analyzing biochar from field trials in central Illinois between 2014 and 2017. To this end, they investigated the impact of VNFA at planting, flowering, pod setting, and seed filling stages or their combination on red gram production.
The results were surprising. Result: While adding nitrogen at all four timings increased yields in almost every case, the benefits in yield were not sufficient to pay for the fertilizer. Emerson Nafziger, professor emeritus in crop sciences, noted that while there have been yield increases with this practice these are not rates at which farmers should be running their fields because the extra costs would outweigh the extra bushels resulting considerable financial loss.
What is interesting, the researchers discovered that split application of nitrogen just single time during reproductive stages (flowering-pod setting-seed filing) rarely gave any significant improvement in yields. That the plant “made do” with the natural nitrogen supply (from the soil) and, possibly to some limit, its partnership with the soybean-bacteria.
Conclusion
This profile is contrary to the widely accepted view that modern soybean varieties respond favorably to increased soil N2 fertilizer levels. The study suggests that soybeans can generally provide itself with enough of its own nitrogen by naturally fixing it with the help of some soil nutrients, which ought to be sufficient for producing high yields at a fairly low cost and without throwing additional nitrogen into streams or adding high doses to a corn-on-soy rotation. This information is important to farmers because it will allow them to be able to make better decisions on farm input purchases, become more cost effective, and environmental friendly with their agricultural practices.
