Toxic? Wood Chips in and around garden Q

Discussion in 'Organic Gardening' started by drcarl, May 14, 2009.

  1. drcarl

    drcarl Active Member

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    Q: Are there any trees or shrubs which, when chipped and used on pathways, and for building future soil, that are poisonous or otherwise NOT suited for being in or around an ~organic~ garden?

    I am systematically replacing almost useless grass with yummy organic edibles...am loving the process and the results.

    A neighbor just took down a few trees and we acquired a load of chips. It smells SO good and is steaming now as it begins to decompose. The chips are from: Poplars, a Fir, some Maple and some Photinia.

    We are building a berm by stacking various yard clippings and plan to cover the berm with these chips and later with some soil. We would also like to cover some of our grass with cardboard and apply a layer of these chips for walkways. I don't want to use anything that would compromise or otherwise mess-up the organic-ness of our gardens.

    Thanks in advance for any and all replies.

    --Dr Carl
     
  2. greengarden bev

    greengarden bev Active Member

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    I love your enthusiasm! What an excellent inspiring project. None of the species you mention will harm your soil. Decomposing wood chips are the ultimate organic cover for walkways.

    One thing you mention makes me pause: putting soil on top of a base of pure organic matter (decomposed wood chips). IMO, it would be a better idea to imitate nature and put the soil down first, then cover it with your wood-chip compost. Or at least mix up the soil with the compost before laying it down. Good garden soil has, well, dirt in it. It is never pure OM.
     
  3. Millet

    Millet Well-Known Member 10 Years

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    The standard rule in the commercial nursery industry whenever Populus and Quercus spp. chips are to be used as an ingredient in container growth mediums, for nursery trees or shrubs, is to compost both species for a minimum of four to six months. This allows for the leaching of the excess manganese that is present in both of these species. Millet - (1,347-)

    VHEMT Starts with you never ever me.
     
    Last edited: May 14, 2009
  4. greengarden bev

    greengarden bev Active Member

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    Dr. Carl,

    Millet seems compelled to inject reasons why something can't or ought not be done, usually quoting an industry source. Still his posts are useful if only to prompt me to do research I wouldn't normally do-- it's usually an excellent learning experience.

    Anyway, if your wood chips are steaming now, they are well on the way to being compost and will be perfectly safe to use in your berm.

    Also, to refute the "manganese buildup" myth, here's a quote from Linda Chalker-Scott, who recently did an exhaustive review of the scientific literature comparing landscape mulches, published in December 2007 in the Journal of Environmental Horticulture. If you e-mail her, she'll send you the study. Here's her web site: http://www.puyallup.wsu.edu/~linda chalker-scott/Fact sheets.html

    I'm quoting her on the GardenRant blog (http://www.gardenrant.com/my_weblog/2008/09/the-hort-guru-a/comments/page/1/#comments)

    I forgot to address the manganese build up. There's no evidence this happens to the soil under wood chip mulches. Where you can find buildup of heavy metals is in the leaf litter - and eventually soil - of orchards and other landscapes that have been treated with foliar fertilizers or pesticides that contain zinc and other metals. Manganese and other metallic nutrients are associated with plant enzymes, most of which are in the leaves. You wouldn't expect much to be found in the wood.

    So don't worry about wood chips. Good luck with your project.
     
  5. Millet

    Millet Well-Known Member 10 Years

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    Composting is commonly used to reduce the carbon-nitrogen ratio to a more favorable level. Manganese is present in large quantities in the bark of most hardwood tree species. If this excess manganese is not removed by leaching or composting or balanced with iron, plant growth will be poor and toxicity symptoms are likely to appear. In every major commercial nursery, hardwood bark is improved by being composted with five to six pounds of urea per cubic yard, for two to four months. This will not only allow for the leaching of excess manganese which can be a problem with bark of populus and quercus , but will also allow for the decomposition of very fine bark particles, and small wood particles, and any cambium layer that was stripped from the logs in the de-barking process. The result is a fair growth medium component at a reasonable cost as long as the percentage is kept low. DrCarl being completely organic may not wish to use urea as a catalyst. Depending on the type of organic nitrogen, and amount of organic nitrogen he uses, DrCar's compost time might have to be extended,

    Remember several factor:

    The amount of nitrogen added must be sufficient for the particular mix component in question.

    Moisture must be present in order for the microorganisms to do their work.

    Microorganisms need oxygen as well as moisture so the pile must be turned or mixed and aerated frequently.

    A compost pile no more than three to four feed deep and spread over a sizable area is preferred over one 10 to 12 feet deep.

    Whatever you do, have fun in your garden this summer. Take care. - Millet (1.347-)


    VHEMT starts with you never ever me.
     
    Last edited: May 15, 2009
  6. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    Oleander wood is very toxic, but I doubt you'll find that in Seattle. Poison-ivy and Poison-oak could also be a health hazard in mulch.

    Otherwise, avoid any wood chips made from wood treated with preservatives.
     
  7. drcarl

    drcarl Active Member

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    Great replies! Thanks!

    I'll answer further later (mainly that I don't really expect to grow anything in an organized way for at least a year, and would in fact be surprised if it was usable before 2 years)

    ;)

    --DrCarl

    PS - I wonder if the organic urea I manufacture daily would be s suitable catalyst? lol.
     
  8. Millet

    Millet Well-Known Member 10 Years

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    DrCarl, I suppose it all depends, on the quantity and how good your nitrogen content is. Take care. - Millet (1,345-)
     
  9. drcarl

    drcarl Active Member

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    I think I'll surround everything with creasote-laiden railroad ties...JUST KIDDING!

    No oleander, poison oak or ivy wound-up in the pile of chips. Nice to know what's there is OK.

    I believe that the continual wetness of the Pacific NW (and perhaps a hose) combined with time will provide enough wetness for leaching. As-is, there is plenty of air circulation within the new berm since I have not moved any of the chips to the berm yet - probably this weekend. I guess I should poke it with a spading fork when the feeling strikes me...just like I should go poke my real compost pile someday soon.

    The berm is only about 3 feet high...the across the street neighbors were an eyesore so we thought to build-up that end of our property and grow some privacy. Now, the eyesore has been repossessed, many junk cars moved, will surely have a new owner, and we are more interested in building a little bit more bed, in eeking out a few more square feet of the elusive "full sun," and in growing things we love to EAT!

    Good point about adding some actual soil; I probably will not do this right away...so much to do.

    I am warmed by all the good data. This forum seems to come through with good answers consistently.

    I'm attaching a couple of shots of my pile of aromatic, steamy fresh wood chips.

    Thanks to all,

    Dr Carl
     

    Attached Files:

    Last edited: May 15, 2009
  10. sue1

    sue1 Active Member 10 Years

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    Just a thought here about putting wood chips/bark mulch in your garden: In the Pacific Northwest, sowbugs can be a big problem - they love rotting wood, or anything that is rotting really. When they reach large numbers, they can also start "attacking" your living plants/veggies. I know of many folks who have problems controlling them. Rotting wood and compost really encourages them to decide to take residence in your yard. However, I still use bark mulch, and still compost. This year I find them particularly problematic, and I would appreciate any advice as to controlling them while still proceeding with my composting, etc.

    sue
     
  11. Ron B

    Ron B Esteemed Contributor 10 Years

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    Wood chips are the best mulch. See Chalker-Scott's web site for additional discussion. As in the forest and other natural places, where quantities of plant matter accumulate on top of the ground, in the garden wood chips belong on the surface of the soil, rather than buried within it.

    The local climate is far from continually wet. I am already struggling with seriously droughty soil conditions in some planting areas. Spring occurs from Feb. to July here, with summer finally prevailing after the 4th. By this time of the year soils have been gradually warming and drying for months.
     
  12. canadiyank

    canadiyank Active Member

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    Free mulch - fantastic! Have fun with them. I like mulching and composting more than I like growing things, I think!
     
  13. CowValGardenGal

    CowValGardenGal New Member

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    I am not sure if this is still relevant, since your initial post was in 2007, almost 7 years ago, but I found it interesting that so many posts cautioned you against this method. Interesting because if you consider that the forest breakdowns trees as organic matter, and as they decompose they provide nutrients for seed growth (nursery trees) and also Hugelkulture is the process of taking logs and piling them one on top of the other and then adding soil and planting into it...as the trees/wood mater breakdown they provide the nutrients for the plants on top - just like in the forest!
    Also, I know that Maple, which is used in smoking of meats and Fir (needles are used in herbal teas and throat lozenges) are not toxic, but a quick search on Wiki found this entry for Photinia:

    Toxicity[edit]

    Some varieties of Photinia are toxic due to the presence of cyanogenic glycosides in the vacuoles of foliage and fruit cells.[10] When the leaves are chewed these compounds are released and are rapidly converted to hydrogen cyanide (HCN) which blocks cellular respiration. The amount of HCN produced varies considerably between taxa, and is in general greatest in young leaves.[11] Ruminants are particularly affected by cyanogenic glycosides because the first stage of their digestive system (the rumen) provides better conditions for liberating HCN than the stomachs of monogastric vertebrates.[12]
     
  14. Ron B

    Ron B Esteemed Contributor 10 Years

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    The logs and other woody debris that pile up on the top of the ground in forests here are critical to the maintenance of a presence of water during the annual summer drought - water contained in old logs has even been said to be a source of drinking water for animals. I was walking along a log one summer on Camano Island (Island County, WA, a generally reduced precipitation area) and had the top of it collapse, allowing my shoes and feet to become instantly and totally immersed in the reservoir of cold water contained within.

    In a cultivated setting when a layer of organic debris is not maintained over a soil the condition of the soil can deteriorate markedly. Woody debris such as arborist wood chips is the most effective for protecting the soil. However, such material may kill herbaceous plants not adapted to forest conditions or otherwise unable to cope with being buried by it.
     
  15. woodschmoe

    woodschmoe Active Member 10 Years

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    I've been tempted to bury my slash in the past to take advantage of this for plantings, and it works--the middling diameter logs remain spongy and wet for years. Problem with this locally, at least, is near inevitable honey fungus or other such fungi. Same with Hugelkulture. Exception seems to be blueberries I planted in the base of rotting stumps (where huckleberries were already growing out of the top), which are thriving and require no irrigation, and receive a near constant renewal of their mulch as the stump breaks down.

    Seems most reported issues (including mine) arise when the wood (chips or logs) are buried, rather than used at the surface...Out of a bunch of Persian Walnuts I've planted in a variety of spots, three that are growing through old stick/brush berms have outgrown the others by a factor of two (the others being planted in open spots with wood chip mulch), and receive no supplemental water, the area around the roots and extending about two feet up the trunk being loosely piled brush amongst Oregon Grape. Always cool and moist underneath, even in August/September droughts.
     
  16. Ron B

    Ron B Esteemed Contributor 10 Years

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