"Alan Gould" wrote in message
...
In article , J Jackson
writes
Genuine question are there any other plants that can be used too?
What about other deep rooted plants like docks, dandelion,
horseradish?

It is claimed that any deep rooted plant may contain nutrients,
trace
elements and minerals which shallow rooted plants do not have access
to
in a continually cultivated and cropped area of ground. Most deep
rooted
plants will be beneficial to compost for that reason if added to the
heap in moderate quantities. For making liquid infusions, more
tender
and less fibrous material is easier to handle and simpler to bio-
degrade, thus nettles and comfrey are preferable for that purpose to
e.g. horseradish, docks etc.

The principle in an organic system of horticulture is that what is
taken
from soil by plants needs to be replaced. Manufactured chemicals may
go
some way to replacing NPK, but there is a good deal more to soil and
plant needs than just those basic elements.

I don't understand why you say " may go some way to replacing
NPK....."
Why not replace those elements completely? Moreover, my understanding
is that most farmers who use fertilisers tend to *overreplace* the
elements used by the crops.

Also, there are fertilisers which, in addition to NPK, contain the
other elements needed for plant growth. As a matter of fact, I
suspect that simple fertilisers like Growmore do in fact contain
sufficient trace elements. The only reason only NPK concentrations
are declared is simply that that is all they have to do to comply with
the law.

Franz