On 09/08/2010 21:31, Daddy Tadpole wrote:

"harry" a écrit dans le message de
...
On 8 Aug, 21:53, "Daddy Tadpole" wrote:
All plants need calcium (lime), but some of the ones we particularly
like
can't survive with more than trace amounts. We also know that soil that
contains some lime, but not too much, gets depleted if you repeatedly
harvest stuff and don't make good the deficiency.

Hence my question: what plants would most rapidly deplete soil that
contains
just a a bit too much lime for rhododendrons and suchlike? A politically
correct approach could be to plant the right kinds of veggies between
the
bushes. Possibly someone might be able to propose a more practical
approach,
for example a method of preparing batches of low-lime soil.

Regards

Lime in soil is removed by rainwater which is acid due to dissolved
CO2 and by rotted plant material which also is acid.
If the soil is naturally limey (ie the subsoil is limestone or chalk),
then it very gradually subsides and caves are formed.
If the soil sandstone based it will be naturally neutral but rainfall
will make it acid (or rotted plant material) & lime may be needed for
most plants. But it has to be renewed. If it isn't, it will just
revert to it's true nature after a while. I can't think of a way of
accelerating this process.

The idea was that if your soil contains a bit too much lime (but not too
much), it should be possible to get rid of some of it relatively rapidly
by growing lime-snaffling stuff you can eat or put on the compost. The
cabbage family would be candidates except that they would be likely to
stop growing properly before the soil gets as depleted as you want.
Whatever ones' impression at a given moment, it doesn't rain enough to
make much difference...

It is probably easier to make a patch of almost pure composted material,
leaf mould and peat free compost to put your lime haters in. There are
some rhododenrdons that will tolerate a bit of lime - so if you choose
wisely you could grow them.

It is worth doing a pH test on the soil to see how far out it is.

In reply to Janet, there's nothing terribly politically incorrect about
trying to grow things that are a bit way out for the environment you
have. Otherwise, you could just let those lush indigenous weeds take
over completely.

It is always interesting to grow things that don't really match your
conditions (eg too tender) - but be prepared for a few failures.

Regards,
Martin Brown