In 2008 the department of Biological Farming Systems of Wageningen University studied the effects of EM (“effective microorganisms”; see here (in Dutch)). The most important results have now been published in the scientific journal Crop Protection. The disease suppressive activity of EM, combined or not with Bokashi, was studied in various soils against Pythium ultimum in cucumber Rhizoctonia solani in carrot. In general, there was no consistent disease suppressive activity. Also no effects were found in diversity of the bacterial communities. After 1 week, an increase in biological soil activity was measured after applying sterilized or unsterilized EM/Bokashi, but this had disappeared 7 weeks later.
Shin & al. in Crop Protection, https://doi.org/10.1016/j.cropro.2017.05.025