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.
--
Alan & Joan Gould - North Lincs.