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queuetue

The SFG Rhizosphere

queuetue
15 years ago

I'm not a botanist, by any stretch, but I know a tiny bit about mycorrhizal fungi - essentially, they are fungi that exist in healthy soil, forming long fragile threads that harmlessly and symbiotically enter roots, transporting water and nutrients into the plant, and gathering the rich byproducts of photosynthesis to sustain themselves.

VAM fungi cultures form over time, and are easily destroyed by disrupting soil - protecting and reaping the benefits of soil biota like these is one of the largest reasons for the no-till movement. I know that without proper VAM fungi, many plants such as corn and potatoes have a hard time reaching their full potential.

When I harvest from a SFG, I do what I can to disturb as little of the soil as I can manage, so whatever culture is forming can maintain itself - but the frequent addition of compost, with it's own fugal and bacterial load must mean the biota in a SFG is constantly in flux.

I was wondering who else has considered these factors, and might know even more than I do about them, and how they interact with a intensive succession planting method like SFG.

Comments (22)

  • engineeredgarden
    15 years ago

    I just wanted to let you know that this was one of the most disturbing things I've ever read. Ha! Ouch, my brain hurts! Maybe someone else will understand all of this, 'cause it absolutely blew my mind. Whew.......

    EG

  • Dan _Staley (5b Sunset 2B AHS 7)
    15 years ago

    This is the tradeoff in double-digging - the wish to keep an undisturbed solum. In SFG, your disturbance is supposed to be only a few inches, so disruption is purportedly minimal.

    The issue in tight spaces is the inability to do good crop rotation to avoid exhaustion and the difficulty in cover cropping for green manure in the SFG. As long as you are not tilling down 24" and leave most of your roots, your overall soil structure (esp in a raised bed) will be fine for what you need.

    The real issue with no-till is the wholesale disruption by industrial agriculture, and no-till is a reaction to this disruption(s): altering N and P and C cycles, hydro cycles, till pan, erosion, monocropping, etc. Small-scale gardening is overall much better for the soil than industrial ag and IMHO the addition of OM into the solum makes up for disrupting the little guys. They are adapted to disturbance (but not adapted to high-speed plows and overapplication of N.

    Dan

  • sinfonian
    15 years ago

    Ok, unlike EG, you had me right up to Dan's undoubtedly well-informed analysis.

    Thankfully I never dig down 12 inches in my beds, though I do remove most of the roots when I rip out plants. I've never known to leave them. I wouldn't think they'd break down fast enough to allow for new roots to grow.

    If someone could speak to that I would appreciate it.

    Oh, and Dan, I think you said we are fine on this issue, am I wrong? From what I understood I think we are. /boggle

  • queuetue
    Original Author
    15 years ago

    EG,

    Uh-oh. I was hoping you'd be one of the ones nerdy enough to engage me in this. :)

  • rj_hythloday
    15 years ago

    Very interesting topic, I've read that it's good to leave roots in to keep mulch from blowing away in the winter, but I've also wondered if they break down enough to plant in the same space the next year.

    A question I've had is that I plan on planting many perrenials flowers and such that will be remaining in place and I'm wondering how the OM they are planted in will hold up. If I should plant them in as deep of OM as possible or just try to top dress it to make up for lost OM?

  • engineeredgarden
    15 years ago

    queuetue - I can be pretty sophisticated with alot of different topics, but for this one - i'll just have to sit back and learn from all of you. That's cool, I like learning new things.

    EG

  • shebear
    15 years ago

    Here are a few sites that talk about the soil food web.

    http://www.soilfoodweb.com/03_about_us/approach_pgs/a_01_benefits.html

    I can't believe you've not seen all this. Soil microbiologist Dr. Elaine Ingham is a fascinating speaker. I think you can find some videos of her on youtube too.

    I'm so into this stuff that it's the backbone of the community garden we're trying to create. So far after 3 years, we've repaired the environment enough to have frogs. The place had been a dirt parking lot for heavy equipment. The dirt was gray and you couldn't make a dent in it with a rock bar. Now we have mice, rabbits, an armadillo, a possum, a hawk and 5 owls and now frogs. The produce we grow goes to the poor. The city is amazed at what we've done.

    When you get done with all that, you need to see what Bill Mollison has done. Then see how Geoff Lawton has used swales to fight drought. Both have videos on youtube.

    We are in an time of great change for dealing with the earth. We are acquiring the knowledge to fix some of what we've done.

    Here is a link that might be useful: Soil food web

  • gringojay
    15 years ago

    Hi queuetue,
    Most kinds of fungal rhizomes that are broken/cut do not magically realign & perform individually the same. VAM is one of these types.
    Millet is the plant to grow when you want to colonize a beneficial mycorrhizii culture in your soil. In this case it is the millet root ball that is left in the ground and you don't incorporate the above ground plant matter into the soil.
    Most millet varieties get tall & as an inter-crop you might not have a layout that can accommodate the shade in a SFG .
    Some growers may still take advantage of millet's ability to symbiotically increase mycorrhizal soil content, because millet is a quick crop & there are dwarf varieties. You do not have to grow the millet to it's seed harvest stage for the soil fungii colony.
    I offer no advice on the cost effectiveness, benefit & pitfalls of commercial ecto/endo-mycorrhizii blended preparations for use in open ground cultivation, greenhouse, containers or under tree canopy.
    If you couldn't get organized & during your growing season feel you want to experiment with indigenous soil fungii here's how.
    Look for a field where a non-toxic native weed patch flourishes in dry conditions. Take some of the dirt clinging around those weeds' root hairs & then put that dirt, with it's attached root hairs, shallowly in the soil around the roots of your SFG plant. You will water this in & follow your seasonal watering method of course. If your experimental plant is nestled in compost then pull that compost away, & keep the compost back (if you later mulch use something more akin to plant litter).

  • sb158
    15 years ago

    Oy! Yet another thing to worry about, as if succession planting, companion planting, and organic gardening wasn't bad enough, now you want me to worry about soil fungi? Makes my head spin just thinking about it, though I don't doubt it is important...

  • anniesgranny
    15 years ago

    I agree with sb158...it might be important, but it sure takes the fun out of gardening and could be a big turnoff to someone who is just beginning to garden. If I have to go back to college to learn how to properly grow a carrot, forget it! Hey, new gardeners....shove a seed or two into some dirt, give it some water...watch the miracle happen. Not everyone has to make it rocket science.

    Granny

    Here is a link that might be useful: Annie's Kitchen Garden

  • gardener_sandy
    15 years ago

    LOL at anniesgranny! I love your attitude towards growing things. My Dad taught me to open a row, drop in some seeds, use my foot to push a little soil over the seeds, stomp lightly, and then jump out of the way! And sure enough, with only a little help, most things grow beautifully with that "care."

    That said, I think the more we learn about the soil, the better gardeners we will be. It doesn't take a botany or horticulture degree to understand that the less we interfer with nature's way of doing things (with some exceptions) the better off our gardens will be.

    I've stopped tilling my garden plot and started adding more and more OM, thanks in large part to things I've learned from people like queuetue and others here. And the results are pleasing. More knowledge and less work sometimes actually does mean better return on effort.

    Keep it up. This kind of conversation is fascinating.
    Sandy

  • Dan _Staley (5b Sunset 2B AHS 7)
    15 years ago

    What AG said.

    I don't think its anything to worry about. Leave some roots for breakdown products for the little guys and you are fine. Soil gets disturbed in ecosystems all the time - animals, tree fall and uprooting, frost heave, erosion, other geomorphic processes. BTW, we have found that mycorrhizal inoculation in the urban forestry field doesn't work, so we've stopped doing it for the most part where money is an issue.

    Fungi are unbelievably tough, resilient, and diverse (sinfonian: if you're a mushroomer, I used to live in Enumclaw and have a fantastic spot for chanterelles and a separate one on the way to Crystal for elfin saddles [still have some from several years ago]). Soil bacteria and viruses have been around for so long they've figgered it all out and they'll be here long after we destroy ourselves.

    IMHO this is not a problem in home veggie gardens. At larger scales, however, this is a big problem. Plant a couple of peas for Rhizobium only and turn them under if you must.

    Dan

  • sinfonian
    15 years ago

    Every situtation is different. Shebear NEEDED to know all about soil to turn a dessolate parking lot with compact, dead soil into a lush oasis for plant and animal alike. I for one am really glad she did and got great results from it. (Though don't you think the owls will eat the frogs? Just curious.)

    However, for the new gardener, or one that utilizes RBs with Mel's Mix or the like, this level of detail is far from necessary to grow a lush garden.

    It is very interesting though! If you want you can never stop learning it seems.

  • jbest123
    15 years ago

    My daughter use to work for a major producer of Mycorrhizal Fungi products. I had access to products that were nearing the end of there shelf life free. I ran a little test using a product called Mini Plug. I planted twelve tomato seeds in a commercial seed starting soil and twelve tomato seeds in the same soil with Mini Plug added.
    {{gwi:1262796}}
    I do not think there is a question as to its effectiveness, there are too many reports, technical paper to the affirmative. To me the question is, is it cost effective? The home gardener can do things like, when hiking in the forest take a plastic bag with you, and collect puffballs and burry them in the garden or compost pile. You can also dig up some of the forest soil and put that in the garden/compost pile. When clearing the garden of old veggie plants, cut the stalk at ground level leaving the roots, come spring the main stalk can be lifted from the soil leaving the feeder roots in place. If you are doing succession planting, simply plant the new plant beside the old stalk stub, the new plant roots will find there way down into the soil.

    John

    Here is a link that might be useful: Johns Journal

  • Dan _Staley (5b Sunset 2B AHS 7)
    15 years ago

    I do not think there is a question as to its effectiveness, there are too many reports, technical paper to the affirmative. To me the question is, is it cost effective

    Exactly. We don't think it is (YMMV) & don't recommend it.

    Some of our folks here are dropping native soil from areas with trees into the planting hole for this purpose. One debate we are having is B&B trees may have michorrizae & that is an advantage, balanced by the fact that so many B&B are planted too deep, with resultant increased mortality. The GF is bidding for container trees for all her projects this year & establishment will be looked at as well.

    Dan

  • gardener_sandy
    15 years ago

    A brief tale regarding forest soil:

    About 20 years ago I double-dug the foundation borders along the front of our house. When I put the soil back into each trench, I added a shovel or two of soil I had stolen from beneath the leaf litter in our woods along with some peat moss and compost. I have never added anything else to those borders except a top dressing of mulch and a very light dusting of fertilizer every couple of years. The soil is still light and fluffy and grows anything I put in it very well. I credit the forest soil since I've done essentially the same thing elsewhere without that addition and the results were nowhere near as good or long lasting. Just MHO.

    Sandy

  • rj_hythloday
    15 years ago

    ^^

    I'm really enjoying this one, any one else got anything?

  • sinfonian
    15 years ago

    Ah, leaving the stalks in the ground. That must be what the folks did at that public garden I blogged about yesterday. Good idea! I certainly could have done that with my corn last fall. Oh well.

    As for forest soil, we have a forested wetland behind our house. I don't suppose it would be the same thing? It's only a 50-100 foot buffer between houses and a park.

    Great thread! Interesting and new to me!

    Here is a link that might be useful: Sinfonian's garden adventure

  • greenbean08_gw
    15 years ago

    I think I cut off most of the plants instead of pulling them last fall, the corn for sure. I wondered how it would work leaving the corn stubble there. I was a little worried they'd be in the way this season but the other day I came across one and it came right out.

    I find this topic very interesting but a bit mind-boggling (from some previous reading). It won't be something I will worry about but something I will try to understand a bit better and to keep in mind. There may very well be some very simple things I can do that may make a difference.

    Here is a link that might be useful: Tales of a Transplanted Gardener

  • Dan _Staley (5b Sunset 2B AHS 7)
    15 years ago

    I wondered how it would work leaving the corn stubble there.

    We're windy here as well as where greenbean is and I wonder whether leaving stubble disrupts the wind at ground level enuf to give a better chance at soil retention. I cover a good fraction of my beds for the winter just to keep soil around, but this might help too...

    Dan

  • rj_hythloday
    15 years ago

    I read last year (after I had pulled all of my roots, even the corn) that it would help the leaf mulch stay in place.

  • Melissa Houser
    15 years ago

    Hmmm, my conclusion from all of this, then, is that I wasn't "just being lazy" when I didn't pull the old, dead plants from around the house. I was actually protecting the rhizosphere to improve this year's plantings. :)

    I'm so proud of myself... now, to convince hubby! ;)

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