"nswong" wrote in news:2le8s2Faloo7U1@uni-
berlin.de:

"Salty Thumb" wrote in message
...

Diamon also having high C/N ration, I can assure you it will not
reduce the N available to plant when use as mulch. g

Diamonds (?) do not contain any biologically accessible carbon.

Yes, "diamond" not diamon.

This is my point, it's the carbon available to bacterial, not the
actual amount of carbon that causing temperary N deficiency.

If the carbon do in a slow release form for bacterial, it will not
cause a suddent bacterial bloom even there is a lot of carbon there.

I'm not sure what you mean by this. The carbon in cellulose is not going
to be released in any significant quantitiy without bacterial action.
The bacteria will not have action without also N being present. When
both are present the bacteria will use both the N and C, making less N
available for plants. [I don't know what happens to the N after the
bacteria get it (it has to go somewhere)]. Regardless, bacteria will not
be able to decompose diamonds.

It really depend on the available carbon instead of the total carbon
contain.

Both newspaper and sawdust have high cellulose percentage. Sawdust is
reported to reduce nitrogen availability when used in a compost pile.

I believe that is starch and sugar in the sawdust that cause this, not
cellulose or lignin. I believe newspaper do lost some of it starch and
sugar while in the process.

Cellulose is made from repeating units of glucose (a simple sugar) [1].
Starch is also made from glucose [2]. So unless there is some other form
of sugar you are thinking of, I don't think so.

[1] http://www.psrc.usm.edu/macrog/cell.htm
[2] http://www.poco.phy.cam.ac.uk/resear...rch/whatis.htm

I believe mulch will reduce N available to plant when the carbon(in
liquid form) leach to the soil in rain, but not when there is no
water soluble carbon are present in mulch.

Many forms of N are water soluable and is leached away by water
without any interaction with C, mulch or newspaper. You may actually
get additional N during rain.

So, either mulch will cause temporary N deficiency or not will depend
on the C/N ratio make available by rain to soil bacterial.

I will say that, some mulch will and some mulch will not causing
temporary N deficiency. It will depend on the amount of the C and N
available to bacterial that do bring to soil by rain water.

I think the amount of N from rain is relatively minor, but I do think the
water and biological activity is important, otherwise the decay rate is
slow. If you have low N to start, then the decay rate will be low and
your plants have low N. If you have high N, some of that N will be used
by decomposers leaving X amount for the plants, which still might lead to
low N. If your top layer is biologically active, then most of N from
rain will be intercepted before it reaches the plant roots.

In my impression, newspaper does not contain much water soluble
carbon. It need enzyme to convert it, and that is a slow process.

Cellulose is broken down by actinomycetes.

I believe this process are rather slow. Do actinomycetes got the
ability of N fixation from air?

I think the speed is dependent on N availability, temperature and maybe
water availability. I don't think they can fixate N from air like legume
inhabiting bacteria (rhizobium, phylum proteobacteria) or others, so they
have to use other sources (otherwise, wood would decay quite quickly in
open air).

If I'm not wrong, cellulose are not one of the form of carbon that
directly available by bacterial.

Despite the name and superficial resemblance, actinomycetes are
prokaryotic bacteria, phylum actinobacteria. (Fungi are all
eukaryotic.)

To tell the true, I don't know what is actinomycetes. g

"The mulitcellular actinobacteria include filamentous prokaryotes that
were originally mistaken for fungi. Unfortunately, even though they are
prokaryotic in all of their features, they are still sometimes called
'actinomycetes'." _Five Kingdoms_, Margulis and Schwartz, p.98, 3rd ed
1997. [-mycetes = plural of Greek "mykes" = "fungus"]

The other important thing to know about actinomycetes is that they
decompose cellulose.

Have you read the sci.bio.agriculture group?

I do take a look there when I looking for agriculture newsgroup few
month ago. Forgetted why I decide not to subscribe this group. May be
due to the lack of traffic, or it's more on academic than practical.
Not sure.

Do you think it's good for me to looking information there?

I only checked a few times, and you are right, aside from the spam, the
traffic is light and usually very academic. But if I were using my land
for commercial interests, I would keep an eye on it.

hmm ... I don't know what happened to the group ... I only see
sci.agriculture now (no '.bio') and that has quite a bit of useless junk
in it.

If you read the link I posted earlier,

I'm doing a research for X/HTML now for writing some program, will
read the link you provide later.

I see it probably doesn't say anything you don't already know.

it classifies earthworms in 3
groups. One of them i don't remember and is probably not relevant.
The other two are nightcrawlers and regular earthworms.

IIRC:
1. Litter dweller. Those live in the litter/mulch. E.g. red worm for
worm composting
2. Surface dweller. Those "regular earthworms" work their way most of
the time horizontally.
3. Burrower. Nightcrawler/dew worm.

Another link I
provided gave the population density for a certain species at some
test location as 0-7 per sq. meter. At this rate, and the size of my
flower bed, I think any detrimental effect by landscape fabric is
minimal.

The reason of some place are 0 per sq. meter, the other are 7 per sq.
meter are due to the environment of that place.

I do believe that for a same place, a landscape fabric do reduce the
earthworm population by reduce the accessability to food for
earthworm.

okay

I think, since it is a worm, eventually it will reproduce at a
sufficent rate to exploit any available opening.

Yes, to a far lower population in the total area.

I think if there is any population loss for type #3 in my case it is
neglibile. The total area of my flower bed is not large and assume the
original poster's is more or less the same. Additionally, one dimension
is significantly shorter than the other, so migration is not severely
affected. This is also assuming the normal population is in the 0-7 per
sq. meter range.

The other kind of earthworm does not live in static burrows and only
comes out during times of rain. I would guess that being subterranean,
they would also be minimally affected by landscape fabric.

They do need food, the landscape fabric do block organic matter to
reach the soil. If you mixed in a lot of manure yearly to the soil
that is another story.

I do not know exactly what earthworms(#2) eat, but plants do secret
organic debris from their roots, so perhaps falling surface debris is not
the only source of food for them.

I don't think plant roots are impermeable to water. I don't know how
a chunk of clay is going to get into my flower bed. It has been
several years and I have no problems with water blockage. Even if
some clay or other amendment (as below) were spread over the fabric,
water is a very effective solvent and while the clay or amendment is
not guarranteed to pass, the water certainly will.

It do reduce the infiltration, and causing run off when rain are
relative heavy.

I have not noticed this, but there is a gutter above the flower bed that
blocks most water flow. But even when the gutter was removed I did not
notice any pooling.

You can try this experiment: Cover some soil with newspaper. Time
how long it takes to develop an opening. It takes over 2 months in a
temperate climate.

Put other organic mulch on top of newspaper, it make difference.

Now, if that is true, then won't the weed blocking effect of the
newspaper be mitigated? It seems to be of marginal benefit when being
used in an active flower bed. You would have to rely on the soil biota
(which would occur with or without the newspaper) for suppression after
the newspaper decays. There may be significant initial suppression, but
it seems to me that would be eventually negated by the additional
fertility (of decaying mulch and other amendments).

Any holes that develop are not from macroscopic organisms.

I believe soil life do included those like earthworm, groundbettle,
millipede, fungus...

I only noticed bacterial decay when I tried, but I did not cover with
organic mulch.

Plants will grow through, but those opening are not available to
macroscopic organisms (being blocked by the plant).

Plants roots will dead, especially feeder roots, after the dead roots
decay, tunnels are there. This applied to fungus as well.

Yes, but this takes time.

I will be surprised if you can come up with any large organism (other
than termites, paper wasps and people) that will deliberately make a
hole in the newspaper.

Here I do saw rat making big holes anywhere. ;-)

okay, "and rats"

To be fair, cover
half the newspaper with organic mulch (I have not tried this) and see
what happens. You can cover the other half with a banana leaf or
something if you are worried about sun effects on organisms (you can
take the leaf off when it rains or artifically add water to simulate
tho condition). I predict the only difference is that mulch side
will have accelerated decomposition (1 month to first hole vs. 2
months).

It really depend on how abundant life form are there. An example are,
I put the newspapers under my curing compost that have abundant of
groundbettle, millipete, earthworm... I do quite sure it take less
than three days to have a first hole that go through all the layer of
newspaper if the newspaper are wet.

See above ... won't this make the newspaper less useful for weed
suppression?

It's not just the size of the hole but also any electrical or chemical
effects that may cause what ever you are adding to clump together
(similar to hard water calcification of drain pipes on a smaller
scale). Also, the landscape fabric regardless of the holes may be
semi-porous to water. That is not necessarily true for the solute.
[by 'hole' in this case, I'm refering to the factory made approx.
millimeter sized openings uniformly distributed over fabric area, not
the openings made by users to plant through.]

My point are, if the end result are nutrient in liquid form can be
filter/block, it's sure that it also will causing run off, and not
much water can get from rain for soil that is directly under the
landscape fabric. So why landscape fabric? ;-)

okay, but why would you add nutrient to the surface of your mulch (and
not directly to your flowers) or at least under the mulch? I know you
said you like to top dress, and let organisms do the transport, but this
seems inefficient for a small scale (ranking time to nutrient
accessiblity higher than labor time).

I think you are wrong about the soil not getting much water. I rarely
water my flower bed, and have the gutter blocking run-off from the roof,
and the plants appear very healthy.

The good thing about landscape fabric is you don't have to spend any time
weeding. Once every three months (or even longer), you can take a look,
a few thing may grow on top and these can be picked off by hand. No
significant root penetration occurs, so even a child could do it.

More importantly, there is no significant penalty for delayed removal.
Without landscape fabric, a weed may grow quite large and maybe even go
to seed or vegatatively propagate in 3 months (at the same time competing
with desirable plants for resources). With landscape fabric, the weed
may grow large, but the root system will be significantly impaired and
probably will not seed before it is pulled.