In article ,
Franz Heymann wrote:

If iron, which is easily available in the form of scrap, is capable of
acidifying soil, why is it that I found 5 references which mention that the
only realistic way of acidifying soil is the addition of large quantities of
sulphur, and none which mention anything about iron being used for this
purpose?

Because high levels of iron are poisonous to most plants! You can
kill the plant life in a pond by chucking scrap iron in. Furthermore,
how does sulphur acidify the soil, being as close to neutral as it is?

I have related in this thread that the soil in my garden in a place where
there is a
lot of rust from an ancient inicinerator has the same pH as that at a
position far away from this source of iron. Please explain.

For the third time, my chemistry stops long before the level at which
I could do that. But I do know enough of the mechanisms involved to
know that naive measurement of pH is unreliable, and have some
knowledge of why. I also know that iron is well-known to have an
"acidifying" effect on soil, but can't tell you more about what that
means and how it does it.


Regards,
Nick Maclaren.

"Nick Maclaren" wrote in message
...
In article ,
Franz Heymann wrote:

If iron, which is easily available in the form of scrap, is capable of
acidifying soil, why is it that I found 5 references which mention that
the
only realistic way of acidifying soil is the addition of large quantities
of
sulphur, and none which mention anything about iron being used for this
purpose?

Because high levels of iron are poisonous to most plants! You can
kill the plant life in a pond by chucking scrap iron in. Furthermore,
how does sulphur acidify the soil, being as close to neutral as it is?

I accept that there are devious strings of reactions which the sulphur might
undergo which would in effect end up with sulphuric acid.


I have related in this thread that the soil in my garden in a place where
there is a
lot of rust from an ancient inicinerator has the same pH as that at a
position far away from this source of iron. Please explain.

For the third time, my chemistry stops long before the level at which
I could do that. But I do know enough of the mechanisms involved to
know that naive measurement of pH is unreliable, and have some
knowledge of why.

So do I.
Nevertheless, a determination of pH is the only possible way of quantifying
the acidity of the soil. I know the measurements are not easy, and the
little stick-in-the-soil pH meters are crap. The (serious) kits sold for
determining the pH of aquarium water by titration are quite reliable and
produce eminently repeatable results when used to test soil pH.


I also know that iron is well-known to have an
"acidifying" effect on soil, but can't tell you more about what that
means and how it does it.

I have my doubts if we are going to arrive at a resolution, so perhaps we
might as well drop the subject.

Franz

The message
from "Franz Heymann" contains these words:


I have my doubts if we are going to arrive at a resolution, so perhaps we
might as well drop the subject.

So soon?

"Clunk clunk clunk clunk clunk...."
Franz: "What's that noise?"
Nick "I'm no audiotechnician, but probably the sound of a dropped thread".
Franz: "How many decibels?"
Nick : "I don't know, but it's a dropped thread"
Franz: "That can't be right."

"Clunk............................................ clunk...........................cl...
Franz: What's that noise?"


etc. etc.....
:-)

Janet

The message
from "Franz Heymann" contains these words:


I have my doubts if we are going to arrive at a resolution, so perhaps we
might as well drop the subject.

So soon?

"Clunk clunk clunk clunk clunk...."
Franz: "What's that noise?"
Nick "I'm no audiotechnician, but probably the sound of a dropped thread".
Franz: "How many decibels?"
Nick : "I don't know, but it's a dropped thread"
Franz: "That can't be right."

"Clunk............................................ clunk...........................cl...
Franz: What's that noise?"


etc. etc.....
:-)

Janet

The message
from "Franz Heymann" contains these words:

I have my doubts if we are going to arrive at a resolution, so perhaps we
might as well drop the subject.

iron

Clang!

/iron

--
Rusty Hinge
horrid·squeak&zetnet·co·uk
http://www.users.zetnet.co.uk/hi-fi/tqt.htm

The message
from "Franz Heymann" contains these words:

I have my doubts if we are going to arrive at a resolution, so perhaps we
might as well drop the subject.

iron

Clang!

/iron

--
Rusty Hinge
horrid·squeak&zetnet·co·uk
http://www.users.zetnet.co.uk/hi-fi/tqt.htm

The message
from "Franz Heymann" contains these words:

I have my doubts if we are going to arrive at a resolution, so perhaps we
might as well drop the subject.

iron

Clang!

/iron

--
Rusty Hinge
horrid·squeak&zetnet·co·uk
http://www.users.zetnet.co.uk/hi-fi/tqt.htm