University of Nebraska Extension says deciding whether to inoculate soybeans should be based on soybean nitrogen needs, the probability of a yield response and data.

Soil pH, when soybeans were last planted, soil texture and any experience with droughts or floods can all factor into whether inoculating soybeans will provide a return on investment.

Soybean production is expanding.

Soybeans obtain up to 70% of their total nitrogen requirement from biological nitrogen fixation conducted by Rhizobia bacteria colonies (nodules) living on soybean roots. If the nodules fail to form, the plants will become deficient in nitrogen and significant yield reductions can occur.