EDUCATION · TERRAFERM
What Are Effective Microorganisms?
A plain-language guide to EM — where it came from, how it works, and where it fits into TerraFerm’s mission.
What EM Is
Effective Microorganisms (EM) is the general name for a defined group of naturally occurring, beneficial microbes first cultivated together in the 1980s by Dr. Teruo Higa, a professor at the University of the Ryukyus in Japan. Rather than relying on whatever organisms happen to show up in a given batch of compost, EM starts from a specific, repeatable blend of microbial families selected for how well they work together.
The term spread through Dr. Higa’s books on effective microorganisms and the now out-of-print An Earth Saving Revolution series, and it’s become shorthand across composting, gardening, and agricultural circles for this same core group of microbes. You’ll often see it sold or labeled as “EM-1,” which refers to one specific commercial formulation built on the same underlying science — not a different technology. See TerraFerm’s EM1 Effective Microorganisms page for what “activation” means and how EM1 is used.
How It Works
EM works through fermentation, not decomposition. The microbial families in an EM blend — lactic acid bacteria, photosynthetic bacteria, yeasts, and others — are co-cultivated so their byproducts feed and stabilize each other, producing a liquid that stays viable far longer than compost tea or a one-off microbial extract. That stability is the practical difference: an EM-based brew can sit on a shelf for months to years, where most homemade microbial teas have to be used within hours.
Once diluted and applied, those same organisms go to work wherever they land — breaking down organic matter, competing with less desirable microbes, and supporting biological activity in soil, compost, water, or litter. For the full breakdown of the five core microbial families and how EM compares to compost tea, see TerraFerm’s Compost Tea vs. Effective Microorganisms page.
Why TerraFerm Focuses On It
TerraFerm is the microbial products division of PlanetaryCARE.org. Our education and consulting work is built on the same EM science described above — TerraFerm’s own fermented product line is called Advanced Syntropic Antioxidative Microbes (ASAM), a name we use to distinguish TerraFerm’s specific kit-based formulation and process from the broader EM category, not to claim a different underlying science.
Good microbial fermentation should be teachable and repeatable, not something only large operations can access. Instead of shipping finished Mother Culture or promising guaranteed yields, TerraFerm focuses on giving growers and operators — starting with poultry — the pre-measured inputs, a defined brewing process, and the education to run their own EM-based program on-site.
Where Effective Microorganisms Are Used
EM shows up anywhere someone wants more control over microbial activity: composting and bokashi, soil and plant health, pond and water management, and on-farm fermentation for animal agriculture. In animal ag, water-line and litter application is the most common use — supporting cleaner litter, lower ammonia pressure, and more stable house conditions.
See TerraFerm’s poultry program for how that looks in practice, or the broader animal agriculture page for other sectors. For soil, compost, and plant-specific use cases, see TerraFerm’s Effective Microorganisms in Agriculture page. If you’re ready to source EM, see Where to Find Effective Microorganisms.
COMMON QUESTIONS
Effective Microorganisms FAQ
What does “EM” stand for?
EM stands for Effective Microorganisms — a term for a defined blend of naturally occurring, beneficial microbes first cultivated together by Dr. Teruo Higa in the 1980s. It’s also sometimes labeled “EM-1,” referring to one specific commercial formulation of that same underlying microbial group.
Is EM the same as compost tea?
No. Compost tea extracts whatever organisms are present in a batch of compost, so its makeup varies and it typically has to be used within hours. EM starts from a specific, co-cultivated blend of microbial families and is stabilized through fermentation, giving it a much longer shelf life. See TerraFerm’s full comparison for the details.
How is TerraFerm’s ASAM different from generic EM?
ASAM (Advanced Syntropic Antioxidative Microbes) is TerraFerm’s own fermented product line, built on the same core EM science described above. TerraFerm provides pre-measured kits and a defined brewing process so growers can produce a consistent, shelf-stable ASAM brew on-site rather than sourcing a one-size-fits-all commercial product.
Where is EM commonly used?
Composting, soil and plant health, pond management, and on-farm fermentation for livestock and poultry operations are the most common applications. Application method and dilution vary by use case.