On Fri, 17 Jun 2005 11:02:49 +0100, Martin Brown
wrote:


All is a bit of an exaggeration I will admit, but enough of the ones
nearest the surface to hamper oxygen diffusion (and in a plastic pot
that is pretty much where oxygen has to enter to get to the roots).


CO2 cuts some of it back to carbonate especially on the surface when the
dissolved salts get concentrated by evaporation. In really hard water
regions with dark compost you can see it happen over a couple of years
as the surface sets to a concrete like crust.



Problems with certain epiphytic plants with high oxygen demand at the
roots. Belgian tapwater is incredibly hard even by Yorkshire standards.

Miracid and their ilk are much more effective at stabilising the calcium
in solution, but I still would not rely on it regularly for lime hating
pot plants.

Regards,
Martin Brown


OK, I can see how a surface crust might build up over a long time and
under rather extreme circumstances, but not a problem I would expect
normally and with proper attention to surface cultivation.



--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net