On Mar 16, 6:43*pm, songbird wrote:


**worms do secrete calcium.

The worms will just recycle the calcium already in the environment so this
would have no net effect.


* if a worm ingests a calciferous fragment
they will grind it in their gizzard along
with everything else they ingest. *add to
that secreted calcium. *i think all of
these things would increase available
calcium in the soil (which is what is more
important to plants than calcium levels
tied up in forms that aren't very
accessible).


Songbird, below info may help clarify:

http://cronodon.com/BioTech/Earthworm_nutrition.html

“It was originally thought that the calciferous glands excrete excess
calcium, since earthworms living in calcareous
soils ingest huge amounts of calcium carbonate (limestone/chalk) -
sometimes too much to digest and absorb and
so it is presumed that they must rid themselves of excess calcium.
However, whether or not an earthworm lives in
calcium-rich soil does not seem to correlate with calciferous gland
function. The glands have been shown to
contain large amounts of the enzyme carbonic anhydrase, which fixes
carbon dioxide gas by reacting it with
calcium to produce calcium carbonate. Carbon dioxide is generated by
respiration within the earthworm and must
be excreted since it is acidic. Experimental removal of the
calciferous glands has been shown to result in
increased acidity (lowering of pH) in the earthworm's coelomic fluid.
This suggests that these glands have an
important role in acidity (pH) regulation. All organisms function best
within a certain pH range and the body must
be maintained within this (often very narrow) range. The calcium
carbonate excreted by these glands may be so
abundant as to form crystals or concretions that pass out with the
worm's faeces (or casts). Perhaps in winter
these glands are not required as much, since the respiration rates of
earthworms may drop with a fall in
temperature. Calcium excretion may also help to neutralise the humic
acids in the ingested soil.”