Effective microorganism

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Effective microorganisms (EM) are various blends of common predominantly anaerobic microorganisms in a carbohydrate-rich liquid carrier substrate (molasses nutrient solution) of EM Research Organization, Inc.,[1][2] The efficacy of EM on agricultural crops has been studied throughout the world. A review article (2013), which studies the nature of EM and the effect of EM on growth, yield, quality, and protection of vegetable plants, has concluded “in 70% of published studies, it was concluded that EM had a positive effect on growth of vegetable, while, in the other 30%, they had no significant influence.[3]

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.[4][5]

Possible constituents[edit]

One trademarked product was originally (c. 1985) marketed as EM-1 Microbial Inoculant.[6] Such EM blends include:[7]

In his presentational essay "EM: A Holistic Technology For Humankind", Higa states:"I developed a mixture of microbes, using the very common species found in all environments as extensively used in the food industry–namely Lactic Acid Bacteria, Photosynthetic Bacteria an[d] Yeasts (..) EM (..) was developed by accident (..)"[8]


The concept of "friendly microorganisms" was developed by agriculture scientist and Professor Teruo Higa, from the University of the Ryukyus in Okinawa, Japan. He stated in the 1980s that a combination of approximately 80 different microorganisms was capable of positively influencing decomposing organic matter such that it reverts into a "life-promoting" process. Higa invoked a "dominance principle" to explain the asserted effects of his "Effective Microorganisms". He claimed that three groups of microorganisms exist: "positive microorganisms" (regeneration), "negative microorganisms" (decomposition, degeneration), "opportunist microorganisms" (regeneration or degeneration). Higa stated that in every medium (soil, water, air, the human intestine), the ratio of "positive" and "negative" microorganisms was critical since the synergistic symbiotic microorganisms followed the trend to regeneration or degeneration. Therefore, he claimed that it was possible to positively influence the given media by supplementing with beneficial microorganisms.


The concept has been challenged. This was acknowledged by Higa in a 1994 paper co-authored by Higa and soil microbiologist James F Parr. They conclude "the main limitation...is the problem of reproducibility and lack of consistent results.".[9]

Various experimenters have examined the use of EM in making organic fertilizers and investigated the effects of the fermented organic fertilizer on soil fertility and crop growth, not distinguishing the effects of the microorganisms in the EM treatments from the effect of the EM nutrient solution in the carrier substrate. The resulting effects on crop growth depend nonspecifically upon multiple factors, including effects of the introduced EM nutrient solution with microorganisms, effects of the naturally microorganism-rich bio-organic fraction in the soil, and indirect effects of microbially-synthesized metabolites (e.g., phytohormones and growth regulators).[10][11][12][13][14][15]

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."[5][16]

In a study (2010), Factura et al. collected human fecal matter in airtight buckets (Bokashi-dry toilet) over several weeks, adding a mix of biochar, lime and soil after each deposit of fecal matter. Two inoculants were tested—sauerkraut juice (pickled sour cabbage) and commercial EM. The combination of charcoal and inoculant was very effective in suppressing odors and stabilizing the material. EM had no advantage over sauerkraut juice.[17]

Due to the fact that only very few studies exist which have used scientific methods to investigate additives based on EM, any claims made by manufacturers regarding long-term beneficial effects need to be evaluated in the intended conditions.

In Agriculture, the effect of long term application of EM compost for soil fertility and crop yield improvement was investigated at China Agricultural University from 1993 to 2013. This filed experiment shows that “The application of EM in combination with compost significantly increased wheat straw biomass, grain yield, straw and grain nutrition compared with traditional compost and control treatment.” Also, the experiment indicates the significant efficacy of EM on organic nutrition sources.[18]

In water treatment, Abdel-Shafy, H.I et al. (2014) examined the different hybrid treatment process for handling greywater for reuse. This study proves the reduction of TSS, COD, and BOD with the addition of EM. Furthermore, it states that “Addition of effective micro-organisms (EM) to the raw greywater enhance the settling and aeration process effectively” and “increasing the EM dose to 1.5ml/L and settling time up to 4.5 h followed by aeration for 90 min could improve the final effluent up to the permissible level”. This final effluent meets the ‘Egyptian Guideline’ for unrestricted water reuse.[19]

In addition, the effect of EM on the reduction of COD and BOD of wastewater is proved in the studies with Yamuna wastewater (the river of the Ganges in northern India) and the rubber processing wastewater.[20] Namsivayama. S.K.R et al. (2011) also illustrates that “The result of the experiment shows that EM has the potential to improve the effectiveness of treatment of domestic wastes”.[21]


EM-Bokashi, invented and marketed by Higa, uses commercial EM to ferment organic kitchen waste. Treatments with EM-Bokashi show no effects on soil microbiology or as bio-fertilizer which are caused by the EM microorganisms. Observed effects relate to the effect of the nutrition rich compost carrier substrate of the EM-Bokashi preparation.[5][16] Natural Yogurt, or Sauerkraut juice (pickled sour cabbage) can be successfully substituted for commercial EM-bokashi bran.[22][23]

In a community course of the Christchurch city council, New Zealand, 4-13-year-old students were invited to "learn the science behind reducing and utilising organic waste as a resource by turning it into natural fertilisers",[24] using EM in Bokashi composting for home kitchen waste at the EcoDepot/EcoDrop.[25]

In India, effective microorganisms have been used in an attempt to treat some sewage-polluted lakes in Bangalore in 2015.[26]

After the Bangkok floods of 2011 effective microorganisms were used in an attempt to treat polluted water.[27]

Scientific methods to investigate applications of wastewater additives have come to the conclusion that long-term beneficial effects are not proven.[4]

Pit additives used for improving the performance of sanitation systems do not work, because "the quantity of bacteria introduced to the pit by dosing additives is insignificant compared to the number already present in the faecal sludge. Similarly, while some additives operate on the logic of adding more nutrients to the sludge to feed bacteria and encourage their growth, faecal sludge is already rich in nutrients."[4] With regards to this situation, effective microorganisms is used for treating polluted waterways caused by faecal sludge, usually mixed with bokashi mudballs, to disinfect and consume sludge and disinfect water.

Currently, an Italian company named Nami Project created in 2003 by Patrizia Krisa and Alessandro Griso in Verona (Italy), has created a multipurpose line of products featuring a completely new formula based that started from Higa's EM-Bokashi. Thanks to the new formula, which lets co-exist an even greater number of microorganisms populations, they succeeded in making those kind of microorganisms suitable for different uses. The NAMI (なみ, nami; meaning wave in Japanese) can be used as body care, detergent for living spaces, food, agriculture fertilizer, pet care and even construction.[28]


  1. ^ Effective Microorganisms EM and EM・1 are the trademarks of Em Research Organization, Inc., Uruma City, Okinawa, Japan. "EFFECTIVE MICROORGANISMS". trademarkencyclopedia.com. Advameg, Inc. Retrieved 27 November 2015.
  2. ^ "Global Partners". emrojapan.com. EM Research Organization. Archived from the original on 8 December 2015. Retrieved 27 November 2015.
  3. ^ Olle, C.; Williams, Y. (2013). "Effective microorganisms and their influence on vegetable production – a review". Journal of Horticultural Science & Biotechnology. 88 (4): 380–386. doi:10.1080/14620316.2013.11512979. S2CID 87867402.
  4. ^ a b c Foxon, K; Still, D (2012). Do pit additives work?. Water Research Commission, University of Kwazulu-Natal, Partners in Development (PiD), South Africa.
  5. ^ a b c Mayer, J.; Scheid, S.; Widmer, F.; Fließbach, A.; Oberholzer, H.-R. (2003–2006). "Effects of 'Effective Microorganisms EM' on plant and microbiological parameters in a field experiment, Zürich, Switzerland" (PDF). 9. Wissenschaftstagung Ökologischer Landbau. http://orgprints.org/9691/. Retrieved 21 August 2016.
  6. ^ "Trademark Guidelines". emrojapan.com. 2011. Archived from the original on 1 November 2011. Retrieved 13 November 2011.
  7. ^ Szymanski, N.; Patterson, R.A. (2003). "Effective Microorganisms (EM) and Wastewater Systems in Future Directions for On-site Systems: Best Management Practice." (PDF). In R.A. and Jones, M.J. (Eds). (ed.). Proceedings of On-site '03 Conference. Armidale, NSW, Australia: Lanfax Laboratories. pp. 347–354. ISBN 0-9579438-1-4. Retrieved 14 November 2006.
  8. ^ Higa, Teruo. "EM: A Holistic Technology For Humankind". teraganix.com. TeraGanix, Inc. Retrieved 27 November 2015.
  9. ^ Higa, Dr. Teruo; Dr. James Parr (1994). Beneficial and Effective Microorganisms for a Sustainable Agriculture and Environment (PDF). Atami, Japan: International Nature Farming Research Center. p. 7. Retrieved 14 August 2016.
  10. ^ Yamada, K.; Xu, H. L. (2001). "Properties and Applications of an Organic Fertilizer Inoculated with Effective Microorganisms". Journal of Crop Production. 3: 255–268. doi:10.1300/J144v03n01_21. S2CID 73574288.
  11. ^ Pei-Sheng, Y.; Hui-Lian, X. (2002). "Influence of EM Bokashi on Nodulation, Physiological Characters and Yield of Peanut in Nature Farming Fields". Journal of Sustainable Agriculture. 19 (4): 105–112. doi:10.1300/J064v19n04_10. S2CID 84719846.
  12. ^ Xu, H. L. (2001). "Effects of a Microbial Inoculant and Organic Fertilizers on the Growth, Photosynthesis and Yield of Sweet Corn". Journal of Crop Production. 3: 183–214. doi:10.1300/J144v03n01_16. S2CID 83911431.
  13. ^ Xu, H. L.; Wang, R.; Mridha, M. A. U. (2001). "Effects of Organic Fertilizers and a Microbial Inoculant on Leaf Photosynthesis and Fruit Yield and Quality of Tomato Plants". Journal of Crop Production. 3: 173–182. doi:10.1300/J144v03n01_15. S2CID 85678704.
  14. ^ Daiss, N.; Lobo, M. G.; Socorro, A. R.; Brückner, U.; Heller, J.; Gonzalez, M. (2007). "The effect of three organic pre-harvest treatments on Swiss chard (Beta vulgaris L. Var. Cycla L.) quality". European Food Research and Technology. 226 (3): 345–353. doi:10.1007/s00217-006-0543-2. S2CID 56371177.
  15. ^ Daiss, N; Lobo, M. G.; Gonzalez, M (2008). "Changes in postharvest quality of Swiss chard grown using 3 organic preharvest treatments". Journal of Food Science. 73 (6): S314–20. doi:10.1111/j.1750-3841.2008.00842.x. PMID 19241576.
  16. ^ a b Mayer, J.; Scheid, S.; Widmer, F.; Fließbach, A.; Oberholzer (2010). ""Effective microorganisms® (EM)"? Results from a field study in temperate climate". Applied Soil Ecology. 46 (2): 230–239. doi:10.1016/j.apsoil.2010.08.007.
  17. ^ Factura, H.; Bettendorf, T.; Buzie, C.; Pieplow, H.; Reckin, J.; Otterpohl, R. (May 2010). "Terra Preta sanitation: re-discovered from an ancient Amazonian civilisation – integrating sanitation, bio-waste management and agriculture" (PDF). Water Science & Technology. 61 (10): 2673–9. doi:10.2166/wst.2010.201. PMID 20453341. Retrieved 25 August 2016.
  18. ^ Hu, M.; Qi, Y. (2013). "Long-term effective microorganisms application promote growth and increase and nutrition of wheat in China". European Journal of Agronomy. 46: 63–67. doi:10.1016/j.eja.2012.12.003.
  19. ^ Abdel-Shafy, H.I.; Al-Sulaiman, A.M.; Mansour, M.S.M. (2014). "Greywater treatment via hybrid integrated systems for unrestricted reuse in Egypt". Journal of Water Process Engineering. 1: 101–107. doi:10.1016/j.jwpe.2014.04.001.
  20. ^ Rois Anwar, N.Z.; Abu Hassan, M.A. (2013). "Treatment of rubber processing wastewater by effective microorganisms using anaerobic sequencing batch reactor". Journal of Agrobiotechnology. 4: 1–15.
  21. ^ Namsivayam; Narendrakumar (2011). "valuation of Effective Microorganisms (EM) for treatment of domestic sewage". Journal of Experimental Sciences. 2: 30–32.
  22. ^ "Make your own FREE bokashi starter", "Newspaper Bokashi", "Yogurt whey as a starter culture", 12 September 2008. Retrieved 7 November 2013.
  23. ^ Spuhler, Dorothee; Gensch, Robert; et al. "Terra Preta Sanitation". SUSTAINABLE SANITATION AND WATER MANAGEMENT TOOLBOX. SSWM, seecon international. Retrieved 25 August 2016.
  24. ^ "Fertilising for the Future". ccc.govt.nz. Christchurch City Council. Retrieved 27 November 2015.
  25. ^ "A Guide to Effective Microorganisms" (PDF). envismadrasuniv.org. Christchurch City Council. Retrieved 27 November 2015.
  26. ^ Mohit M Rao. "Micro bugs may help in restoring our embattled water bodies". The Hindu.
  27. ^ "EM balls produced by royal project". The Nation. 2 November 2011.
  28. ^ "Probiotic Microorganisms". Nami Organic. 2003. Retrieved 2 June 2021.