The effectiveness of ″Effective Microorganisms (EM)″ was investigated scientifically in an organic farming field experiment between 2003-2006 at Zürich, Switzerland, differentiating the effects of the EM microorganisms from the effects of the EM nutrient solution in the carrier substrate of the EM treatments. "The experiment was arranged to separate the effect of the microorganisms in the EM treatments (EM-Bokashi and EM-A) from its substrate (sterilized treatments)." EM microorganisms showed no effect on yield and soil microbiology as bio-fertilizer in organic farming. Observed effects related to the effect of the nutrition rich carrier substrate of the EM preparations. "Hence ‘Effective Microorganisms’ will not be able to improve yields and soil quality in mid term (3 years) in organic arable farming."