Effective Microorganisms (EM) are mainly anaerobic microorganisms in a substrate or medium made of carbohydrate-rich fluid. Most often the liquid substrate is molasses. It is prepared by Effective Microorganisms research organization and its other licensed manufacturers. It is used in composting, waste treatment and farming as it reduces environmental pollution. Effective Microorganisms is possibly constituted by a Lactic acid bacteria- Lactobacillus casei, Yeast- Saccharomyces cerevisiae and Photosynthetic bacteria- Rhodopseudomonas palustris. The effectiveness of Effective Microorganisms although some say that it has no effect on soil which is being studied throughout the world. Even though some say, that Effective Microorganisms has no effect on soil microbiology and crop yield, most of the studies have proved the positive action of EM on growth of crops. Effective Microorganisms are also sometimes called ‘pit additives’ because they are added to pit latrines, waste water treatment plants and septic tanks to improve their performance. However quite a few studies have shown that EM decreases the Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) of waste water.
Effective Microorganisms was first developed by Teruo Higa from University of the Ryukyus in Japan who stated that a combination of about 80 microorganisms is beneficial to decomposed organic matter and it helps in better crop yield.