Dear Marijn,
for clarification: my small company EcoPro is not a manufacturer, but a dealer and promoter of EM (the licensed EM manufactured in India). We got into this as we had obtained samples of EM (in 1999) and tested them in small field trials (seed germination and development of biomass) that convinced us of its benefits; this is to say, instead of talking advertisement style because we want to sell, we sell and promote because we are convinced of the product; in the EM scenario I have come across many dealers with the same motivation. We have also refused to sell EM in cases where EM does not promise benefits or where expectations are above the ceiling.
Benefits are listed in many websites. Personally observed by us are the following:
Yield increases of many crops (veggies, grains, fruit etc.), anything from between a few percent to doubling and tripling/triplicating - these are not controlled studies, but quantified observations from fields; of course, there are additional factors / parameters involved;
Higher stress tolerance of crops (in comparison to neighbouring fields without EM), stress such as untimely rains, droughts, wide-spread pests;
Reduction of offensive odours in toilets (and households and bathrooms), composting yards, animal stables, mixed waste dumpsites, dairy processing industries, distilleries etc.;
(Thanks to reduction of odours and other factors), reduction in fly nuisance and cockroaches, e.g. in stables, on composts, in households;
Reduction of COD, BOD, TDS, reduction and reduced generation of bottom sludge, removal of old scaling (with temporary increase in TDS until scaling is metabolized), etc.
No point in going on, you may as well trust the websites. In response to most inquiries on the potential use of EM (particularly in sewage and effluent treatment and in solid waste management), I rarely ask myself whether EM will work, but at which dosage and at which costs it will work, and whether the management of any set-up will be willing to spend that much for the hoped-for benefit. The sad observation is that money hardly ever is the constraint, but the will and/or capacity to involve mental efforts, training of staff, supervision of work - and, in public services, the lack of interest (for the common good) and the greed for personal enrichment i.e. corruption.
And yes, there are limits to EM use, even if very tolerant to a wide range of pH, salinity, temperature etc. Basic understanding of (micro)biology helps a lot. But small trials are ridiculously cheap (in material costs), hence where there is interest and engagement, even scenarios with less likely benefit can be tested.
As regards EM for farming, our teaching on EM farming starts with 1) insistence on input of biomass (compost, mulching etc.) and 2) observations of adequate moisture conditions, before we move on to 3) the use of EM. Am ready to send you our info leaflets via mail if you want to. Some stuff is also on our website
www.ecopro.in .
Rgds, Lucas
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Dr. Lucas Dengel
Executive, EcoPro
Aurosarjan Complex, Auroshilpam
Auroville - 605 101, Tamil Nadu, India
web:
www.ecopro.in 
