In article , Mike Lyle mike_lyle_uk@REMO
VETHISyahoo.co.uk writes
Kay wrote:
In article .com,

Please can someone with botanical and chemical knowledge explain
this
thing about leaves being acid? I know that peat bogs are acid, but
could someone please explain the process by which pine needles.
holly
etc render the soil acid?

It's yer nitrogen balance, innit, missis? Yer plant, nah, that's like
all nitrogen and yer long-chain molecules an 'at. Yer calcium
compahns, onneuvverand, what is what achieves yer Swiss-style
neutrality, are fahnd in trivial quantities in yer average vegetable
material; an what there is, is leached aht by yer rainfall. Take it
from me, lady: you leave that stuff lyin abaht, you'll ave a bloomin
peat-bog before you can say "Paddy Murphy".

Are you saying that any compound containing nitrogen is acidic?
--
Kay
"Do not insult the crocodile until you have crossed the river"

"Kay" wrote in message
...
In article , Mike Lyle mike_lyle_uk@REMO
VETHISyahoo.co.uk writes
Kay wrote:
In article .com,

Please can someone with botanical and chemical knowledge explain
this
thing about leaves being acid? I know that peat bogs are acid, but
could someone please explain the process by which pine needles.
holly
etc render the soil acid?

Many leaves, stems, barks, flowers etc contain tannins (tannic acid) which
are leached into the soil therefore lowering its pH.

During the decomposition process the acids are either leached away,
neutralised or broken down.

It's yer nitrogen balance, innit, missis? Yer plant, nah, that's like
all nitrogen and yer long-chain molecules an 'at. Yer calcium
compahns, onneuvverand, what is what achieves yer Swiss-style
neutrality, are fahnd in trivial quantities in yer average vegetable
material; an what there is, is leached aht by yer rainfall. Take it
from me, lady: you leave that stuff lyin abaht, you'll ave a bloomin
peat-bog before you can say "Paddy Murphy".

Are you saying that any compound containing nitrogen is acidic?

No many are basic eg ammonium hydroxide

Nitrogen is also an essential component of protein.

Very simply
Woody plants are low in nitrogen when the plants are being broken down the
bacteria need a source of nitrogen and can deplete the soil around them.
When the bacteria die the nitrogen is fixed in soil again and is usable
again.

Also many nitrogen fixing bacteria cannot live in acidic conditions
therefore unusable nitrogen cannot be fixed.

suspicious minds wrote:
Many leaves, stems, barks, flowers etc contain tannins (tannic acid) which
are leached into the soil therefore lowering its pH.
During the decomposition process the acids are either leached away,
neutralised or broken down.

So, my holly leaves would leached away considerably before being broken
down and therefore it could poison/damage plants around it. Yes? Then
again the holly leaves takes ages and ages to decompose ... Looks like
I also might end up with a couple of tons of the stuff. Holly leaves
anyone?!

Very simply
Woody plants are low in nitrogen when the plants are being broken down the
bacteria need a source of nitrogen and can deplete the soil around them.
When the bacteria die the nitrogen is fixed in soil again and is usable
again.
Also many nitrogen fixing bacteria cannot live in acidic conditions
therefore unusable nitrogen cannot be fixed.

Would you perhaps know how long it takes for the soil to be usable
again?

"La puce" wrote in message
oups.com...

suspicious minds wrote:
Many leaves, stems, barks, flowers etc contain tannins (tannic acid)
which
are leached into the soil therefore lowering its pH.
During the decomposition process the acids are either leached away,
neutralised or broken down.

So, my holly leaves would leached away considerably before being broken
down and therefore it could poison/damage plants around it. Yes? Then
again the holly leaves takes ages and ages to decompose ... Looks like
I also might end up with a couple of tons of the stuff. Holly leaves
anyone?!

Depends on your soil type but woodlands usually have good growth in the
spring after the being carpeted in leaves in the autumn.

Very simply
Woody plants are low in nitrogen when the plants are being broken down
the
bacteria need a source of nitrogen and can deplete the soil around them.
When the bacteria die the nitrogen is fixed in soil again and is usable
again.
Also many nitrogen fixing bacteria cannot live in acidic conditions
therefore unusable nitrogen cannot be fixed.

Would you perhaps know how long it takes for the soil to be usable
again?

You misunderstood I meant usable nitrogen not soil.

suspicious minds wrote:
Depends on your soil type but woodlands usually have good growth in the
spring after the being carpeted in leaves in the autumn.

It's really dry around the holly tree, hard and compact. The leaves
rest there for months before showing sign of any decomposition.
Hopefully with a good hair cut the tree won't cast so much shade, and
obviously won't shed so many leaves. This year it was terrible, really
damp, no air going around, and I have another huge lime tree on the
other side, but that's from the street and I can't do nothing about it.


I'll keep the holly shreddings with my leaf mulch and will use it next
year or perhaps the following year. Ta for all your advice.

You misunderstood I meant usable nitrogen not soil.

Off course. I won't risk mulching my lotty plots with the holly leaves.

In article , Janet Galpin
writes
The ivy is quite finely shredded. I wouldn't have thought it could root
from shreddings. I was hoping that covering with black polythene would
create the same kind of conditions as keeping them in black polythene
sacks.

Janet G


I'd dig a trench, fill it with the shredding then cover and start a new
trench etc. Did this last year for the beans and it seems to work fine,
--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk

On Mon, 17 Oct 2005 20:00:16 +0100, Kay
wrote:

In article , Charlie
Pridham writes

"Kay" wrote in message
...
In article .com, La

Please can someone with botanical and chemical knowledge explain this
thing about leaves being acid? I know that peat bogs are acid, but could
someone please explain the process by which pine needles. holly etc
render the soil acid?

I do not think they make the soil acid, (I thought all soils are acid unless
there is some limestone or chalk around to make them alkaline, so soils on
volcanic islands would be acid and counties like Cornwall are largely acid
due to lack of limestone or chalk) but rather if you create soil humus with
vegetable matter it is bound to be acid,

Why is it 'bound' to be acid? Does the vegetable matter start off acid,
or is it the process of decomposition which makes it so, and if so, what
is the chemical process? There's a big gap in my knowledge here!

Most vegetable matter is naturally acidic. I have the following
average pH figures for various vegetables, with a range of typically
+/- 0.2 units:

Cabbage 5.3
Carrots 5.1
Peas 6.1
Potatoes 5.8
Pumpkin 5.0
Rhubarb 3.1
Spinach 5.4
Tomatoes 4.2
Turnips 5.4

Fruits are generally even more acidic:

Apples 3.1
Cherries 3.6
Gooseberries 2.9
Oranges 3.5
Plums 2.9
Raspberries 3.4
Strawberries 3.3

(Source: Handbook of Chemistry and Physics, CRC Press, 1985 edition,
aka 'The Rubber Bible')

Between 10 and 20% of wood is capable of being dissolved in dilute
alkali (the amount depending on the type of wood), implying it
contains significant amounts of acidic compounds, presumably tannic,
gallic and similar acids. Quinic acid is found in hay and leaves.

From all of the above I think it's reasonable to assume that virtually
all the garden waste going onto your compost heap is acidic to some
degree.

In a well-aerated compost heap, more acidic compounds are generated
and carbon dioxide is given off as the organic matter is oxidised by
bacteria. In general terms, oxidation of carbohydrate-type materials
such as the sugars and starches present in leafy and woody material
often proceeds via organic acids before complete oxidation to carbon
dioxide. As examples, bacterial oxidation is used in some industrial
manufacturing processes (e.g. Vitamin C from glucose), and that
half-finished bottle of wine soon turns to vinegar unless air is
excluded.

Having said all that, I read many years ago that leafmould made from
beech trees growing on chalk shouldn't be used for mulching
rhododendrons, as the beech leaves in that situation are high in
calcium. But the author didn't say the leafmould was actually
alkaline, although I suppose it is possible. Salts of weak acids (such
as the organic acids being considered here) and a weakish base such as
calcium can be alkaline if the base is strong enough and the acid weak
enough, which may be the case here. But equally well he may just have
been under the misapprehension that all calcium from whatever source
was bad for rhodies.


--
Chris

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