This (Dutch) post from Belgium, by Frank Anrijs says (in translation):
"If your soil is inoculated with EM, at instance you have these important organisms that will improve your soil and will help your plants. But they have no food! These organisms need organic material also, and you are the one to deliver this to them. Otherwise the improving of your soil is but limited in duration. (...) You should never forget about the basics of your vegetable garden, you can not skip some steps. Start at the beginning:... Give your soil organic matter. Then this EM will come naturally, without you doing something!"
When you can read some Dutch... Here you will find this post...
I can not escape the idea that you have to apply EM for the garden again and again. If this is so, then it does not contribute to a structural improvement of the soil. The earnings on EM rests with EM and not with the soil.
Here a (Dutch) study from the University Wageningen, in 2008: 'Effectiveness of bacteria preparation EM (Effective Microorganisms)', commissioned by the Belgian Association for ecological living and cultivation methods (VELT)... which among other things says, ".... that there is no detectable positive effect of the addition of EM. (...) It has been scientifically proven that organically cultivated soils themselves are already oppressive to disease, partly due to a large diversity of microorganisms. It is therefore questionable whether the suppressive ability may be improved by the addition of cultured micro-organisms to an already very rich soil."
We will see more of these kinds of products for the garden in the future. Nature, biology and ecology are hot business. Ultimately it will not bring us something.