What is Effective microorganism?

Effective microorganisms are various blends of common predominantly anaerobic microorganisms in a carbohydrate-rich liquid carrier substrate of EM Research Organization, Inc.,

Many of the so-called "pit additives" used for improving the performance of sanitation systems, namely pit latrines, septic tanks and wastewater treatment plants, are also based on EM. Despite the claims made by manufacturers, available studies which have used scientific methods to investigate these additives have come to the conclusion that long-term beneficial effects are not proven. Studies have stated that effective microorganisms show no effect on yield and soil microbiology in field experiments as bio-fertilizer in organic farming.