In article , Merl Turkin
wrote:

On Fri, 10 Oct 2003 18:10:25 -0400, Sniz Pilbor wrote:

2. This question is actually a combo question. There are some materials
we are curious about with regard to mulching/composting properties that
aren't found in our composting tome. Could you give any info on their
properties, their vices and virtues in a compost pit? The materials a

[snip]

2c. shells (snailshells, seashells)

Not sure of their breakdown properties, I'd guess they'd take a long
time to breakdown.

A neighbor, whose gardens are uglier'n hell, gathers up sea shells on
every beach journey, or goes clamming & ends up with more shells that way,
& by now has an increasingly thick collection of them tossed in her
gardens, some of the gardens thickly mulched with shells. A couple years
ago I asked her why so many shells & she said the shells "feed" the
shrubs. Which I doubted, though I didn't comment further.

I've since noticed very occasionally in other yards, there'll be lots of
seashells tossed under shrubs or in flower beds. I've even found in my own
yard, while turning soil, evidence that some past owner of this house was
tossing whole shells in flower beds.

If shells are really to be a useful soil ammendment, they'd need to be
crunched up rather than tossed about entire. Crunched up shells can also
be severely alkalinizing, as their composition is identical to limestone,
& should be used with all the plusses & minuses in mind for using lime.
Under my zone's native shrubbery lime would be a bad idea, nearly
everything that grows here wants acidic soil, & the greater majority of
gardened cultivars prefer neutral to acidic soil if not specifically
chosen for regions with inescapably alkaline soils. So using too much of
anything that is a source of lime could be counterproductive.

I have seen recommendations that crushed oyster & clam shells can be used
as a compost additive to help retard the possibility of souring, but I
can't recall reading any actual study that this is so, & remembering to
stir the pile regularly would be a better way to keep it from smelling
bad.

Farm supplies sell big bags of crushed oyster shells for poultry diet
(necessary for chickens to have good eggshell density) & this stuff is
super cheap. There is also a pricier product called "horticultural grit"
which is crushed shells, but very likely the same farm-grade poultry grit
put in a different package.

Many desert plants do like alkaline soil & also like their soil gritty so
it drains instantly, so crushed sea shells might also be a good additive
for a desert garden, though anyone trying it should research beforehand so
as not to accidentally overdo it.

Lime is most often used in lawns, & I'm not sure such a gritty grade would
be quite the thing for lawns, but I don't know. I do not use lime in my
gardens except what's in low-nitrogen slow-release fertilizers, and even
those I use only less often than would most people. A few plants that are
not appropriate to our soils & need alkalinity, I feed them an annual
piece of chalkboard chalk shoved in their roots, as I don't want to alter
the soil pH anywhere else. Even if I were offered a lot of free crushed
shells, I doubt I'd use them in compost or garden, though when offered
free rabbit poo or llama doo, I'm right there with my shovel. But I'm sure
crushed shells do have their place in some gardens, though I still
seriously doubt my neighbor was doing anything useful when mulching with
whole clam shells.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/