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Use Weeds Killer to Keep Weeds Out of My Flower Garden?
"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. |
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