Yeah it could well be. There are a lot of urban-legends around in the world of growing and that could be one of them. None of us know everything.. and all of us think something about growing that isnt scientifically true.
It can be done to some degree either by adding to it or by killing-off the microherd in the soil. If adding to it is something we do, then I'd say that, by deifinition, we've managed the population by increasing it. Bacteria aren't immortal and they do die off quite quickly, especially in the presence of certain additives, poor soil conditions and chlorinated water, so we have to maintain some sort of a level if we're consciously growing organically.
If it was a case of add once and never worry about them again.. none of us would bother dechlorinating our water to avoid killing them all off. So, in my view, we're all trying to some degree to manage the microherd in our mediums when we're growing organically
I don't think anyone can say that it's that black and white (commonly known as the either/or fallacy). We can provide an environment where they can do superbly well and be supercharged.. or one where they struggle to survive but just about hang-on in smaller colonies, or one where they do ok but could do better with earlier bedtimes and more porridge for breakkas.
Case-in-point.. two pots, one fed with molasses and the other not.. you'll find more microherd in the pot fed on molasses.
I also feel it's a bit of a flawed comparison to say that a plant outdoors with limitless soil to grow into is anything like one grown in an isolated little pot indoors that isn't even growing in real soil, with all the bad bacterial problems, waterlogging and nutrient buildups that occur in indoor pot plants that outdoor plants don't generally suffer from.
Pffftt.. could be any one of a thousand late-night trawlings on different gardening sites, or debates on another weed forum.. hence why I'm careful not to state them as facts unless I know they are. I seem to remember having a debate about it with a pro organic grower on another weed forum and him saying much the same - that too many bacteria break down the organic matter too quickly, and the speed if they break down too many too quickly, you have a nutrient buildup, potentially leading to a toxicity or lockout.
Scientifically-speaking those potentials hold-true because that's a lot of what the fauna do in the medium (break down organic matter into chelated nutes). I think balance is relevant, so if any plant had TOO many bacteria all burning off energy breaking down nutrients then the soil would eventually become toxic if the plant wasn't using them all.
One thing I said that I'm definitely doubting now was to say that too many microherd create an acidic soil.. but in fact another memory just surfaced that too acidic soil wipes out the microherd.. so.. that's probably confused and unwound.
I think that "restricting" bacterial growth is a very different propsition to "adding too many". I don't think anyone's said that they should be restricted.
