It grows between paving stones in The Netherlands. Under the paving stones is
sand, all the way down.

The tallest hollyhock I ever saw (14 feet and covered in blooms) was
also growing "between" paving slabs. On lifting the slabs (I had to in
the end), I found the roots travelling at least that far in all
directions without any contact with soil. The plant seemed to be
thriving on top of a sand/hardcore base, but I've never understood how.
Seems some plants don't need any nutrition at all.

On Tue, 12 May 2015 13:55:51 +0200,
Martin wrote:
Locally they pump water from the Rhine and spray it onto the dunes, where the
water works are located. The dunes act as a natural filter. Recently they have
skimmed the top off the dunes "to remove alien plants". It could be to remove
the nasty substances that were in the water from the Rhine.

They should rather consider covering the dunes with some of the plants
which serve as a host for water cleaning bacteria. We have Iris,
Salicaires, and Scirpes (I do not know their english, nor the latin
names) for that purpose. Common reed is okay and chosen more often,
while a combination of different species is best.

If the dunes were to be “cleaned�, they would have to be leveled
completely, or replaced, as their tops will not contain most of the
realy nasty stuff, if any. Maybe they just began to look ugly with the
decomposing sludge which should cover the sand after a wile. But chances
are, those workers just removed alien plants. ;-)

Michael

--
Location: Lower Normandy (Orne), France
GnuPG/OpenPGP 4096R/3216CF02 2013-11-15 [expires: 2015-11-15]
sub 4096R/2751C550 2013-11-15 [expires: 2015-11-15]
[Next key will use elliptic-curve algorithm! :-) Get GnuPG!!]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

On Wed, 13 May 2015 00:09:59 +0200,
Martin wrote:
On Tue, 12 May 2015 16:18:42 +0200, Michael Uplawski
wrote:

On Tue, 12 May 2015 13:55:51 +0200,
Martin wrote:

They re moved the whole of the dirty layer. The Rhine has a lot of industrial
pollution in it, not just bacteria.

Did not make that claim. The sand of the dunes does a perfect job for
particles and some chemical pollution, both by providing with its grains
a surface to catch and keep “stuff� and by keeping a lot of the
pollution from simply sinking in deeper. The exact function depends on
the substance, filtered.

I did not mention filtering out bacteria, but *providing bacteria* in
the roots of specialized vegetation that eat, transform and thus clean
away a lot of polluting substances, even before they can sink into the
sand. Usual municipal sewage treatment plants under optimal conditions
may be effective at 70%... I have to guess, what this means; they
probably remove 70% of the pollution but event that is not very clear.

A domestic wet park with two succeeding basins, that works with
vegetation, is almost always better than that and appears to be less
sensible to altering conditions, like a changing volume of water,
temperature and the like, the latter probably for its modest size.
But nearby, such a system serves a whole village, looks nice and does
not smell at all (by the way).

As we are only two on our terrain and use a composting toilet, our
system comprises but 1 single basin, actually divided in two to
alternate between both sides for about two weeks each.

[This does, of course, not necessarily have the slightest impact on
horsetail. I do not have any and thus would not know... Actually, no one
has horsetail here. The pastures do not provide the necessary compaction
of the ground.]

Cheerio,

Michael
- --
Location: Lower Normandy (Orne), France
GnuPG/OpenPGP 4096R/3216CF02 2013-11-15 [expires: 2015-11-15]
sub 4096R/2751C550 2013-11-15 [expires: 2015-11-15]
[Next key will use elliptic-curve algorithm! :-) Get GnuPG!!]
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