Benefits of Inoculating Legume Crops with Rhizobia in the Northern Great Plains

Inoculation of forage and grain legumes with rhizobia is an important process to maximize biological N2 fixation capacity in these crops. Inoculation has the potential of increasing dry matter yield, N yield, and residual N levels. However, yield responses to inoculation are not universal in the northern Great Plains region. In fields that have previously grown the same grain legume crop (i.e., contain an endemic rhizobial population in the soil), positive yield responses occur from one‐third to one‐half of the time. Yield responses to inoculation are dependent upon many factors, but legume species and soil N levels prior to seeding are two important factors. However, given the modest cost of inoculation compared to the potential agronomic benefits, producers are well advised to seriously consider inoculation of their legume crops in all circumstances.