Soybean plants have the ability to form a symbiotic relationship with nitrogen-fixing Rhizobia bacteria, which cause the small swellings on the root system called nodules. The soybean plants are developing rapidly and nodules will start to form shortly after plant emergence. If the plant is around 6 inches tall with the first or second true leaves (trifoliolate leaves) unfolded, nodules will start to actively fix Nitrogen (N) gas into plant available N. The number of nodules will increase until the R5 (the beginning of the seed formation) stage or slightly beyond. In Figure 1, the average number of soybean [...]