In message , Franz Heymann
writes
Mike Lyle wrote,

I wish I knew why these discussions always go round in the same
circles. It's perfectly straightforward: you can feed plants on
relatively pure chemical nutrients prepared in a factory, and they'll
grow. You can also feed plants on impure chemicals such as bone-meal,
dried blood, rotted farmyard muck, etc, and they'll also grow.

The plants can, of course, neither absorb nor digest the materials
mentioned in your last sentence. They have to be broken up by agents in
the soil into simple inorganic substances before the plant can make use
of them. What, then, is wrong with skipping a stage and putting the
required chemicals directly into the soil?

So-called organic husbandry is, by my understanding, a set of techniques
which aim to increase the levels of the 'agents' you mention. Rather
than relying on factories to produce concentrated chemical feeds in an
energy intensive fashion the aim is to increase the soils own fertility
in the long term in a sustainable way. All talk of specific substances
which can be applied to the soil or not is subsidiary to the underlying
approach.

--
dave @ stejonda