Monday, November 22, 2010

Under Soil Critters We Need

Good morning ... how are you today?

The other day someone asked me some gardening questions. I just sent him an e-mail answer and thought I'd post it ... in case you also wanted a bit of information about vermiculture, low-till gardening, and soil organisms.

Of course, Barbara Pleasant's article (referred to in resources) is probably better than anything I'll put together from browsing around ... but between the stuff below and the article you'll get a bit of info.

*Vermiculture* refers to maintaining worms in contained space, giving them food and bedding, and letting them do the work of changing the food into poop – ‘castings’. The castings are a form of compost, containing many nutrients and trace elements. Mixed in with soil, these castings release their nutrients and trace elements through the magic of many organisms; in turn, these move through a moisture and root interface and into the plants. Usually the term vermiculture is used in regards to worm raising in indoor spaces, like apartment kitchens or school rooms, but if someone were raising worms for bait or for sale to people doing in-home composting, the term vermiculture is correct.

In his book, /Mike McGrath’s Book of Compost/, Mike gives a short overview of how to set up a worm composting bin, with the reliable Red Wiggler worms (Eisenia fetida). His most important advice is to do some reading up on the how-to before just going ahead. Just like raising chickens, or having a pet canary or rabbit, there are things to know for healthy critters. I do not know who/where in London deals in red wigglers or vermicomposting set-up kits.

*Low till gardening/agriculture*
Many articles have been written over the last few years which advocate for no-rototill home gardens and no-till or low-till agriculture. The article I've attached has a reference to this. Concepts addressed during no-rototill home gardening include:
- use of deeper mulch to keep weed seeds from germinating,
- that many weeds reproduce from even small root parts and that tilling only chops and distributes these,
- that there is a special group of fungi (mycorrhizae) that are a go-between between plant roots and soil; their work transfers nutrients to plants; it is best to not disturb soil so that their in-soil parts don't get damaged because this affects their in-root parts

Both Organic Gardening Magazine and Mother Earth News (magazines) are solid sources of information. Both have websites. Any book by Rodale Press is a good book. The Rodale Institute website is also interesting, and extends information about low-till into agriculture and carbon sequestration (and organic agriculture) as a major player in mitigating global warming.

*Soil Organisms*
Big topic!

To paraphrase Barbara Kingsolver … “sit down, I’ll make you a cup of tea, and then get ready for more than two hundred words.’

The article below also mentions these. And both Mother Earth News and Organic Gardening magazines or on-line can be searched. But to scale up ...

There’s a seriously cool book out, that I've mentioned before:Teaming with Microbes: the organic gardener's guide to the soil food web. It has really fascinating photos taken with souped up microscopes and way more information than I’ll ever get through, although each page I manage to get through fascinates me. This book is the text book for us ... imagine what the university level book must be!

The Teaming with Microbes book has chapters on many types of organisms that help in the creation and maintenance of healthy soil, in the transfer of nutrients to plants and ultimately the growth of plants. Bacteria, archaea, fungi, algae and slime molds, protozoa, nematodes, arthropods, earthworms, gastropods, reptiles, mammals and birds. It is noteworthy that humans don’t make it into this first section of the book!

Don’t think for a minute that I know what all those things even are! The /Teaming/ authors write that ‘A mere teaspoon of good garden soil, as measured by microbial geneticists, contains a billion invisible bacteria, several yards of equally invisible fungal hyphae, several thousand protozoa, and a few dozen nematodes.’ To me they are all ‘critters’.

As an ensemble – as a whole orchestra – these critters eat and are eaten. They excrete and exude stuff; they incorporate other stuff. They react to what is exuded by plants. Plants react to sunlight and water. All the plants and critters do things for, against and with each other. The interactions are like dozens of spider webs overlaying each other and rotated around and through each other … at least that’s my way of understanding the soil web, which, factoring in time, is really a four-dimensional soil web.

I am easily overwhelmed by what I read. So many complicated systems at work, balancing soil ecosystem with root interface with healthy plants! Sometimes I’m afraid to weed out stuff, lest I mess up the root/moisture/nutrient system of nearby plants I want to nurture.

But sometimes, I’ve just got to yank stuff out. Or dig a hole. Or make a new garden bed in a hurry by turning over the soil – flipping 8” cuts so they are soil up – grass down, adding a layer of compost for mulch and just planting right into it … trusting that all the upended critters will figure out their new world and get on with what they do, despite my mistakes and dithering.

I take heart from just the title of chapter 24: /No One Ever Fertilized an //Old// //Growth// //Forest//./ To me, what this comes down to is that, left alone, growing systems reach a balance. So I try to do less, do gently and watch more … in hopes of finding how the garden balance can take care of itself. This is where I’m coming up to the topics of permaculture and forest gardening, topics I’m only just starting to read on ... and which we'll be finding out more about on December 12.

Because I'm an information weinie ... here's an excerpt from Teaming with Microbes that refers to Mycorrhizae fungi. The Mycorrhizae have been getting a lot of press lately.

From Teaming with Microbes

/Soil fungi also form extremely important mutual relationships with plants. The first is the association of certain fungi with green algae, which results in the formation of lichens. Int his symbyotic relationship, the fungus gets food from the alga, which utilizes its photosynthetic powers while the fungal strands make up the thallus, or body, of the lichen, in which the pair lives. Chemicals secreted by the fungus break down the rock and wood upon which the lichens grow. This creates minerals and nutrients for the soil, soil microbes, and plants./

/The second are mycorrhizae (from the Greek for “fungus-root”), symbiotic associations between plant roots and fungi. In return for exudates from plant roots, mycorrhizal fungi seek out water and nutrients and then bring them back to the plant. The plant becomes dependent on the fungi, and the fungi, in turn, cannot live without the plant’s exudates. …/

/Mycorrhizae have been known since 1885, when German scientist Albert Bernhard Frank compared pines grown in sterilized soil to those grown in sterilized soil inoculated with forest fungi. The seedlings in the inoculated soil grew faster and much larger than those in the sterilized soil. Yet iwa s only in the 1990s that the terms mycorrhiza (the symbiotic root-fungus relationship; plural, mycorrhizae) and mycorrhizal (its associated adjective} started to creep into the agricultural industry’s lexicon, much less the home gardeners’s./

/We’re the first to admit that we were blindsided by the subject – and one of us had written a popular garden column every week for 30 years and never once mentioned them out of sheer ignorance, a state shared with most gardeners. We now know the extent of our ignorance: at least 90% of all plants form mycorrhizae, and the percentage is probably 95% and even higher. What is worse, we learned that these relationships began some 450 million years ago, with terrestrial plant evolution: plants started growing on the earth’s surface only after fungi entered into relationship with aquatic plants. Without mycorrhizal fungi, plants do not obtain the quantities and kinds of nutrients needed to perform at their best; we must alter our gardening practices so as not to kill these crucial beneficial fungi./

/Perhaps gardeners lack appreciation for fungi because all soil fungi are very fragile. Too much compaction of soil, and fungal tubes are crushed and the fungi killed. Clearly fungicides, but also pesticides, inorganic fertilizer, and physical alteration of the soil (rototilling, double digging) destroy fungal hyphae. Chemicals do so by sucking the cytoplasm out of the fungal body. Rototilling simply breaks up the hyphae. The fruiting bodies of mycorrhizal fungi even decrease when fungi are exposed to air pollution, particularly that containing nitrogenous substances./

/Mycorrhizal fungi are of two kinds. The first, ectomycorrhizal fungi, grow close to the surface of roots and can form webs around them. Ectomycorrhizal fungi associate with hardwoods and conifers. The second are endomycorrhizal fungi. These actually penetrate and grow inside roots as well as extend outward into the soil. Endomycorrhizal fungi are preferred by most vegetables, annuals, grasses, shrubs, perennials, and softwood trees./

/Both types of mycorrhizal fungi can extend the reach as well as the surface area of plant roots; the effective surface area of a tree’s roots, for example, can be increased a fantastic 700 to 1000 times by the association. Mycorrhizal fungi get the carbohydrates they need from the host plant’s exudates and use that energy to extend out into the soil, pumping moisture and mining nutrients from places the plant roots along could not access. These fungi are not lone miners, either. They form intricate webs and sometimes carry water and nutrients to the roots of different plants, not only the one from which they started. It is strange to think of a mycorrhizal fungus in association with one plant helping others at the same time, but this occurs. /

/Finding and bringing back the phosphorus that is so critical to plants seems to be a major function of many mycorrhizal fungi; the acids produced by mycorrhizal fungi can unlock, retrieve, and transport chemically locked-up phosphorus back to the host plant. Mycorrhizal fungi also free up copper, calcium, magnesium, zinc, and iron for plant use. As always, any nutrient compounds not delivered to the plant roots are locked up in the funge and are released when the fungi die and are decayed./

If you've made it through all the above and the article, give yourself a pat on the back!!

Dream gardens and I hope you have a good day,

Why's Woman

* A few references*

Kingsolver, Barbara. /A Fist in the Eye of God, /an essay contained in the book/ Small Wonder. /HarperCollins Publishers, 2002. [LPL: 814.Kin]

Lowenfels, Jeff and Wayne Lewis. Teaming with Microbes: the organic gardener’s guide to the soil food web. Revised edition. Portland: Tiimber Press, 2010 [LPL: 631.4 Low]

McGrath, Mike.* *Mick McGrath’s book of Compost. New York: Sterling Publishing Co., 2007. [London Public Library system: 631.875 MacG]
Mike is a former editor of Organic Gardening magazine and his bio says he hosts a Public Radio show called You Bet Your Garden, as well as doing other things. I love this guy’s take on things. The Compost book is a fairly fast, easy and /humourous/ read. It even has nifty cartoons. ‘Vermiculture’ is a term Mike dislikes because it sounds like you’re taking rats to the opera.

Mother Earth News:

Organic Gardening Magazine:

Pleasant, Barbara. /Simple Tips for //Better// //Garden// Soil/. Mother Earth News. April/May 2009.

Rodale Institute:

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