If soybean plants are chlorotic (yellow) and nitrogen (N) deficient despite being inoculated, that probably indicates the inoculant has failed.

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.

Horst Bohner, a no-till soybean specialist from the Ontario Ministry of Agriculture Food & Rural Affairs, says a number of first-time soybean fields that were inoculated this year did not nodulate properly.