Effective micro organism

The concept of 'Effective Microorganisms' was developed by Japanese horticulturist Teruo Higa, from the University of the Ryukyus in Okinawa, Japan. He reported in the 1970s that a combination of approximately 80 different microorganisms is capable of positively influencing decomposing organic matter such that it reverts into a 'life promoting' process. Higa invokes
a 'dominance principle' to explain the effects of his 'Effective Microorganisms'. He claims that there exist three groups of microorganisms: 'positive microorganisms' (regeneration), 'negative microorganisms' (decomposition, degeneration), 'opportunist microorganisms'.
In every medium (soil, water, air, the human intestine), the ratio of 'positive' and 'negative' microorganisms is critical, since the opportunist microorganisms follow the trend to regeneration or degeneration. Therefore, Higa believes that it is possible to positively influence the given media by supplementing positive microorganisms.

The Effective Microorganisms concept may be considered controversial in some quarters and there may not be scientific evidence to support all of its proponents' claims. This is acknowledged by Higa in a 1994 paper co-authored by Higa and soil microbiologist Dr. James F Parr (USDA Agricultural Research) they conclude in their own words that, "the main limitation...is the problem of reproducibility and lack of consistent results."
They go on to write,

...it is difficult to demonstrate conclusively which microorganisms are responsible for the observed effects, how the introduced microorganisms interact with the indigenous species, and how these new associations affect the soil plant environment. Thus, the use of mixed cultures of beneficial micro-organisms as soil inoculants to enhance the growth, health, yield, and quality of crops has not gained widespread acceptance by the agricultural research establishment because conclusive scientific proof is often lacking.

In this same paper Parr and Higa also mention soil pH, shading and soil temperature, and flooding as factors affecting the interaction of 'EM's' with local microbiological organisms, as well as with each other. The philosophical approach that Higa and Parr invoke is the maintaining of pH and soil temperature within conditions known to be detrimental to negative microorganisms as well as the addition of EM's to favorably tip the balance of positive and negative microorganisms in favor of the positive microorganisms.

For these reasons the two proponents of the technology (Higa and Parr) dismiss 'silver bullet' EM's that are only a single microorganism as generally ineffective due to the host of uncertainty about the conditions a single microorganism would be effective in. They cite the scientific acknowledgment of the scientific community that multiple microorganisms (as in the case of Bokashi, invented and marketed by Higa) in coordination with good soil management practices positively influence soil microorganisms and plant
growth and yield. They call for additional research to develop more information on soil microorganisms and their interactions.

At present, there are nearly 30 peer reviewed papers on various applications and secondary products that are available on the market today (EM

  • 1 Microbial Inoculant and EM-X Rice Bran Supplement). These papers include

applications in dioxin remediation, crude oil remediation, use in building materials, and various medical applications.


The use of EM in the bokashi intensive composting process for home kitchen waste has been in use in Christchurch, New Zealand for several years, backed by the local city council, and its use as a plant fertilizer is beginning to be researched locally.