"Shiva" wrote in
news:aHlwYXRpYQ==.e95d73a15c2acb5be5ce83fa2953984b @1044383898.cotse.net:

Joe Doe wrote:


You may choose to regard this as nonsense. However as I have pointed
out the opposite opinion to yours is actually held by numerous
gardening authorities (amend soil rather than replace soil).

I write from my own experience. How about you, Roland? Have you seen
this disastrous effect happen? I would be very interested to hear from
people who are speaking of their own experience. People with too much
time on their hands come up with impressive theories all the time, and
frequently publish articles written in quite the authoritative tone.

There are a lot of theories about this, as you point out; I could refer
you to a bibliography of sources that would curl your hair (mine too!).

I took soil science a long time ago when I was a horticulture major. One
of our experiments involved tracking soil porosity where aggregate and
organic matter were not well integrated. We examined different strata of
materials as well as surrounding clay states (similar to the model of
rose holes that you describe). In situations where clay and organic
matter are not well distributed, water drainage can be impeded, but it
depends on the ratio of clay to organic matter as well as the type of
organic matter used.

There may be situations where backfilling a rose hole with pure organic
matter may work, though the substance of the surrounding material (and
its own aggregate content) may influence it. Where I live we not only
have some heavy clay soil but tar as well; my neighborhood is a few
blocks from the La Brea Tar Pits in Los Angeles. In some of my rose
plantings I've had to backfill with original clay and organic matter but
I always make sure to remove the chunks of tar, which do not facilitate
drainage. :-)

As soil science understands it, the better one distributes clay and
organic matter, the more healthy the soil; both are technically necessary
(as are other chemical structures) for plant life to flourish. There are
times when personal experimentation provides results that don't always
correspond to what soil scientists understand, however. Gardening is
still not an exact science.

----