The availability of nitrogen can be a limiting condition that affects plant growth and ultimately yield. Soybean has the ability to interact with the bacteria Bradyrhizobium japonicum, the outcome of this interaction is a nitrogen fixing nodule that is capable of providing the plants nitrogen needs. Nitrogen fixing B. japonicum strains that interact with soybean are not native to Manitoba, and if soybean is planted, it is strongly recommended that the seeds are treated with a B. japonicum inoculum either on seed or in furrow. In many traditional soybean growing areas inoculant is not used every year. Farmers that have been growing soybeans have questions about the populations of rhizobia in fields with history of soybeans.
In 2013, a four year crop rotation experiment , funded by Western Grains Research Foundation and Agriculture and AgriFood Canada through Growing Forward 2, was established by Dr. Yvonne Lawley at three locations in Manitoba ( near Carman, St. Adolphe, Melita). In 2017 this experiment will be in the soybean test crop phase of the experiment. An important aspect that is not being addressed in this study is the affect that these cropping rotations have on the microbial populations that affect soil health as well as the population of B. japonicum. The ability to use this experimental plot to ask these questions is an opportunity to address fundamental questions about B. japonicum persistence and provide insight to how microbial populations are correlated with crop productivity.