permaculture

[jamesdavid Sneed <harvestcircle@hotmail.com>]

Thanks for offering folks an in-depth description of such a good way to 
replace machinery with human power.

> Date: Tue, 11 May 2010 17:34:12 -0400
> From: venaurafarm@bellsouth.net
> To: permaculture@lists.ibiblio.org
> Subject: [permaculture] Venaura Farm Permaculture: Permanent Biointensive 
> Double-dug Garden Preparation & Handtool Information & Sourcelist
> 
> 
> http://venaurafarm.blogspot.com/2010/05/permanent-biointensive-double-dug.html
> 
> Permanent Biointensive Double-dug Garden Preparation & Handtool 
> Information & Sourcelist
> (work-in-progress - updates frequently)
> 
> The essence of it is that you invest a lot of effort and materials up
> front, inverting the soil, fragmenting the crumb structure, with
> associated temporary disruption of soil life and soil structure,
> oxidation of organic matter and release of co2 through exposure of humus
> to air in order to improve soil tilth, fertility, drainage, water 
> holding capacity,
> cation exchange capacity, organic matter content and overall soil 
> quality provifing an
> improved and healthy medium for hosting beneficial microorganisms and 
> other creatures
> that make garden soil their home. You remove much of the soil in the 
> bed, add organic
> matter and mineral based soil amendments to it, homogenize these 
> materials then
> return the amended, enriched soil mix to the bed. This is done in
> increments of one (typical short (42" to 48") English D-handled *see 
> below) digging
> spade blade width wide and one spade blade length deep for the width of
> the bed (38-50" wide depending on the gardener's height).
> 
> You want highly mineralized soil, high in tilth and fertility, producing 
> vegetables and fruits with exceptional flavor.
> Add rock dust from quarries to your garden soil for trace minerals, 
> microbe food and tilth, permanently eliminating soil
> compaction. This is called siltation pond fines. It is so fine that if 
> you put some in a glass of water it turns cloudy
> and stays that way for quite a while before settling into a layer of 
> sludge on the bottom; so fine it would take a microscope
> to see the individual particles. This is great material to feed plants 
> and soil microorganisms and invertebrates in your garden.
> I think we are talking 200 mesh or finer; some fines are a little coarse 
> by comparison to my basalt/tuff fines and some are an
> aggregate with the largest component almost microscopic, like the talcum 
> powder in pyrophylite fines (dredged from the quarry's siltation ponds).
> To prevent compaction, permanently, fines act mechanically to interfere 
> with clay and silt particles that when compressed when wet become highly
> compacted when dried out - a serious problem for gardeners needing 
> productive high-tilth soil.
> I have used this material to enrich soil for the benefit of plants, 
> microorganisms and invertebrates and to permanently
> prevent any compaction of my soil that would significantly reduce the 
> productivity of the gardens. The materials include
> "siltation pond fines" from the following types of rock: granite, 
> volcanic tuff (maybe basalt, very hard rock, 2nd hardest in NC)
> and pyrophyllite screenings. I am glad to hear that granite, high in 
> silica is a sink for lime making my soil acidic,
> good for most crops, pH 6.1 to 6.6 or so. Tillage is expensive, 
> disruptive of soil life and inconvenient when it needs to be done
> and the soil is too wet; i.e. weeds can get out of control and go to 
> seed when tillage can't be done, like in Spring, to remove them and
> create a fine, weed free seedbed for new plantings. Fines are mixed with 
> existing soil on site, sometimes in a 30 or 40 to 50 ratio.
> The clay or silt particles become permanently separated from each other 
> and cannot be seriously compacted again.
> This effect is also achieved with the addition of compost or manures to 
> the soil. The fines feed the microorganisms
> that help break down the fines and make trace minerals available to 
> plants; these microbes also break down any raw or composted organic matter
> added to soil to become humus, feed released nutrients to crops and 
> improve the soil crumb structure providing added tilth to your garden soil.
> The extra trace minerals in garden soil makes crops taste much better. 
> The famous tomatoes grown in volcanic soils in places in Italy taste so
> good for this same reason. That's how fines relieve compaction and add 
> to soil health and vitality, crop health and disease and predator
> resistance and crop flavor, appearance and keeping qualities. More about 
> fines dissolved in water. In places in the high country areas in
> Eastern countries people drink cold river water that is cloudy and high 
> in mineral content; they live long lives.
> 
> I would remove the top 8" or more of your raised bed-to-be. Then, "in 
> situ" (without turning or inverting the soil layers) tilth
> or dig up and pulverize an additional, lower 8-12" of subsoil; add 
> amendments of all sorts to the 8" of soil you removed then put
> it back in place on top of the subsoil layers you just tilthed - then 
> you will have a "raised bed", the new garden bed surface will
> now extend 4-8" above existing grade.
> 
> This will address any concern about your garden drying out during 
> drought times if you use raised beds. The benefits outweigh the
> disadvantages and with the following technique you will have no problems 
> whatsoever.
> 
> Avoid having paths between the beds that are level with existing grade 
> but ditches or furrows between the beds. These provide
> much needed drainage and you can fill these ditches with mulch, weeds, 
> hay, etc all the way up to the tops of your raised beds.
> 
> You want to to accomplish the objective of increasing depth of tilth and 
> fertility in the soil in your beds. Mulching the top layer is
> mandatory. Mulch will decompose leaving the seedbed fine and loose while 
> leaching humus and compost tea into lower layers of garden soil
> including sub soil areas to depths of several feet (partly because you 
> have already tilled this zone). You want a permanent, notill,
> biointensive raised bed that gets better each year through the action of 
> compost tea, humus and nutrients that leach from the top layers
> into the lower layers; that's a real "trickle-down bioeco-economy" with 
> big pay back in quality produce for the table and for market.
> This is real Pay Dirt as J.I. Rodale described it.
> 
> After this process is completed you need never again turn your soil,
> except to a depth no greater than is necessary to control newly emerging
> weeds, break crust and create a fine, loose seedbed. You now have
> biointensive no-till, permanent raised beds.
> 
> This technology has been around for centuries and it works.
> There is a very big net gain for soil, its inhabitants and the environment.
> 
> See John Jeavons books, Alan Chadwick's literature and lectures (links
> on my website) and Aquatias' "Intensive Culture of Vegetables, French
> System".
> 
> Double digging is as essential and indispensible to gardening anywhere
> in the world, where the climate does not mandate other methods, as grain
> is to bread.
> 
> * -> One of these spades:
> Wooden D-handled digging spade:
> 28" length for most people, 32" for tall people or get the long straight
> handled version, see below.
> http://www.bulldogtools.co.uk/img/products/thumbnails/5610012820_500x263.jpg
> http://www.bulldogtools.co.uk/index.php?mod=3&id=7&rid=1
> Long straight handled version:
> http://www.bulldogtools.co.uk/index.php?mod=3&id=12&rid=1
> This is the big dog on the block when it comes to traditional English
> hand gardening tools; these were available at the beginning of the
> modern organic gardening and farming movement in the 1960's:
> Bulldog - Quality Garden, Contractor and Agricultural Tools
> Rollins Bulldog Tools
> "Bulldog Tools have been made at Clarington Forge in Wigan, England, for
> over 200 years. Generations of Farmers, Contractors and Professional
> Landscapers stand testimony to a quality of product upon which their
> livelihoods depend. The skill and craftsmanship that were the key to the
> company's success in those early days are still maintained and are
> available to this day."
> \|/
> =
> /|\
> For hand tools unavailable elsewhere in the USA see:
> 
> EARTH TOOLS, Inc.
> Walk-Behind Tractors and Compatible Implements
> hand tools for gardeners, homesteaders and farmers.
> 1525 Kays Branch Road
> Owenton, KY 40359
> http://earthtoolsbcs.com
> (502) 484-3988 tel.
> (502) 484-3357 fa
> 
> Indispensable tools from them include:
> 
> G30 - DeWit Seed Bed Rake
> Made of forged steel, the 9 super-heavy duty tines are spaced nearly 2” 
> apart - perfect for ripping up and raking organic material out of old 
> seed beds without pulling all the soil out too. Straight neck allows you 
> to flip over and use the back to flatten bed.
> Head: 16.5” x 4”
> Length: 74”
> Weight: 4.4 lbs
> Price: $59.00
> 
> 53565 - SHW ‘Root’ Hoe
> Heavier head for tougher chopping applications.
> Head: 4.5” x 8.5”
> Weight: 4.4 lbs
> Length: 54”
> Price: $43.00
> Length: 75”
> Price: $49.00
> 
> 54306 - SHW Grape Hoe
> The 'Big Mama' of hoes, available with your choice of two handle lengths 
> (head shipped dis-mounted from handle)
> Head: 9.5” x 7”
> Weight: 5 lbs
> Length: 54”
> Price: $46.00
> Length: 75”
> Price: $50.00
> 
> You will also need (all from Bulldog or Spear & Jackson or other 
> manufacturer)
> 1) a D-handled garden spade (less angle between handle and blade)
> 2) a D-handled digging fork
> 3) a D-handled spade fork
> All of these can be seen at the Bulldog site
> \|/
> =
> /|\
> You will need an eye hoe, preferably the Japanese farmer hoe with
> short handle and a few other tools, available from Hida Tool:
> Hida Tool
> http://www.hidatool.com/shop/shop.html
> (this is the most useful eye hoe to get, the other is lighter in weight)
> Kusakichi Brand #524 Farmer Hoe
> item# blade length overall size price
> N-7524 7inch x 5inch 41inch $49.20
> This is an amazing tool, used to clean silt and OM from between beds to
> put back on beds - ridge making hoe - or move dirt or make beds
> Kusakichi Brand #553 Ridge Hoe
> item# blade length overall size price
> N-7553 15inch x 6inch 48inch $69.60
> Kusakichi Brand #531 Farmer Rake
> item# blade length overall size price
> N-7531 8 5/8inch x 5 3/4inch 41 1/4inch $59.00
> This is a three wide-tined hoe, great for weeding and tilthing,
> disturbs soil structure less.
> \|/
> =
> /|\
> Sneeboer tools are excellent. Great if you can find a source for them in
> the USA. The tools to get from them are the variois sizes and
> configurations of their SEEDING RAKES; they are indispensible!
> They also have a great garden spade and an exceptional Dutch-style spade
> fork, a one of a kind tool, as are the seeding rakes (you will find it
> difficult to do without several sizes of this useful tool.
> SNEEBOER & ZN
> http://www.sneeboer.com/
> Products
> http://www.sneeboer.com/index2.php?page=19
> (an amazing array of quality tools)
> These are the seeding rakes:
> -The best seeding rakes for preparing a seedbed for new plantings are
> -the ones with 6 and 8 medium length tines - the others are less
> -useful for this aplication.
> Sloothark 4t
> 4 long tines & 185 cm length
> http://www.sneeboer.com/index2.php?page=19&articleID=114
> Klauw of Hark 8t
> 8 medium tines
> http://www.sneeboer.com/popup.htm?beheer/ass/img/org_product115-1.gif
> http://www.sneeboer.com/index2.php?page=19&articleID=115
> Klauw of Hark 6t
> 6 long tines
> Tuinhark 8t
> 8 medium tines, 167 cm overall length
> http://www.sneeboer.com/index2.php?page=19&articleID=117
> Tuinhark 6t
> http://www.sneeboer.com/beheer/ass/img/org_product118-1.jpg
> 6 medium tines 167 cm
> http://www.sneeboer.com/index2.php?page=19&articleID=118
> Tuinhark 5t
> http://www.sneeboer.com/beheer/ass/img/org_product119-2.jpg
> 5 long tines 167 cm. length
> http://www.sneeboer.com/index2.php?page=19&articleID=119
> Tuinhark 4t
> 4 long tines
> http://www.sneeboer.com/beheer/ass/img/org_product120-2.jpg
> http://www.sneeboer.com/beheer/ass/img/org_product120-1.jpg
> http://www.sneeboer.com/index2.php?page=19&articleID=120
> Fijnhark 10 t
> http://www.sneeboer.com/beheer/ass/img/org_product207-2.jpg
> 10 medium tines
> http://www.sneeboer.com/index2.php?page=19&articleID=207
> Amerikaanse Hark 10 t
> American style rake
> 10 medium tines
> http://www.sneeboer.com/beheer/ass/img/org_product208-2.jpg
> http://www.sneeboer.com/index2.php?page=19&articleID=208
> 
> http://www.sneeboerusa.com/
> Sneeboer USA
> c/o Cole Gardens
> 430 Loudon Road
> Concord, NH 03301
> phone 603-229-0655
> fax 603-229-0657
> doug@sneeboerusa.com
> 
> Garden Rake, 4 prongs, fine toothed
> http://www.sneeboerusa.com/Images/Large/6007.jpg
> http://www.sneeboerusa.com/Images/6007.jpg
> Width : 5.2 in (13 cm)
> Handle Length : 59 in. (150 cm)
> Price : $83.00
> Product Code : 6007
> 
> American Rake, 10 tined
> http://www.sneeboerusa.com/Images/Large/6070.jpg
> http://www.sneeboerusa.com/Images/6070.jpg
> Width : 12 X 3.1 in (42 X 8 cm)
> Handle Length : 66.9 in. (170 cm)
> Price : $118.00
> Product Code : 6070
> \|/
> =
> /|\
> http://www.the-organic-gardener.com/images/garden-tool-english-spade.jpg
> http://www.vegetablegardener.com/assets/uploads/posts/2873/kg17-double-digging-01_lg.jpg
> http://www.gardeningknowhow.com/images/double-digging.jpg
> http://hubpages.com/hub/HubMob-Topic-Of-The-Week-Green-Thumb-Hubbers-Landscaping--gardening-and-loving-your-yard_1
> http://shop.waycooltools.com/images/1192658156236-807030603.jpeg
> This company offers an amazing selection of good tools for biointensive
> gardeners and double diggers, much to choose from:
> WayCoolTools.com
> # P.O.Box 235
> White Hall, VA 22987
> # 877-353-7783
> # contact@waycooltools.com
> # 434-823-4600
> http://shop.waycooltools.com/category.sc?categoryId=3
> \|/
> =
> /|\
> Here's more; this is good material from the BBC:
> 
> Gardening Guides
> Digging your garden
> http://www.bbc.co.uk/gardening/basics/techniques/soil_digging1.shtml
> Double digging
> 
> Double digging is useful when drainage needs to be improved, or if the
> ground has not been previously cultivated. This is a time-consuming
> process but is worth the hard work and will result in good soil.
> 
> * The soil is worked to a depth of two spades, rather than one, and
> it’s essential to keep the two layers of soil (subsoil and topsoil)
> separate. In order to do this, the lower half of the trench can be dug
> over in situ.
> * Remove the soil from the upper and lower spits of the first
> trench and from the upper spit of the second, placing it aside on the
> ground in three separate, clearly marked piles.
> * The soil can then be transferred from the lower spit of the
> second trench to the base of the first trench, and from the upper spit
> of the third trench to the top of the first. This ensures that the
> topsoil and subsoil remain separate.
> * Continue digging trenches in the same way, until you reach the
> end of the bed where soil saved from the first trench can be used to
> fill the appropriate layers in the final trench.
> \|/
> =
> /|\
> And this great blog article with extensive links on double digging
> using the Chadwick/Jeavons French Intensive biointensive method:
> Double Digging
> http://constructal.blogspot.com/2006/04/double-digging.html
> "In 2004 we also volunteered at the Center for Sustainability to help
> double dig some of their garden plots. Double digging is the first step
> in the bio-intensive gardening technique, which we were unfamiliar with.
> So I did a little bit of research on the technique and this year I am
> going to try it on our garden plot. This technique was developed by Alan
> Chadwick and furthered and promoted by John Jeavons of Ecology Action.
> It aims at maximizing the yield from the available area AND maintain the
> soil quality at the same time through sustainable organic methods of
> gardening. The center for sustainability has a very good webpage about
> this technique. Some other links I found are at the bottom of this post."
> Center For Sustainability http://www.engr.psu.edu/cfs/
> and there, on double digging:
> http://www.engr.psu.edu/cfs/projects/biointensive.aspx
> Ecology Action http://www.growbiointensive.org/biointensive/Ecology.html
> See also Bountiful Gardens http://www.bountifulgardens.org/
> Other links:
> http://constructal.blogspot.com/2006/04/double-digging.html#Links
> Biointensive Gardening Technique
> http://www.engr.psu.edu/cfs/projects/biointensive.aspx
> Bountiful Gardens
> http://www.bountifulgardens.org/growbiointensive.html
> Ecology Action Biointensive Gardening
> http://www.growbiointensive.org/biointensive/GROW-BIOINTENSIVE.html
> Books by John Jeavons
> http://www.growbiointensive.org/biointensive/book.html
> \|/
> =
> /|\
> Soil Quality resources, webforum archives, materials from various lists:
> souscayrous' biological farming & permaculture collection
> Hazelip, Bonfils and more
> http://www.ibiblio.org/ecolandtech/souscayrous
> Soils In Biological Agriculture
> http://www.ibiblio.org/ecolandtech/permaculture/mailarchives/discussion-threads/soil-quality/
> Remineralize the Earth
> http://www.ibiblio.org/ecolandtech/orgfarm/remineralization/remineralization.selected-writings
> Additional Soil Quality Links and Literature
> http://www.ibiblio.org/ecolandtech/soil-links+lit.html
> Compost Tea, Soil Foodweb, Soil Quality Discussion:
> Archive 1
> http://www.ibiblio.org/ecolandtech/SoilWiki/message-archives/composttea+soilfoodweb+soilquality/1/maillist.html
> Archive 2
> http://www.ibiblio.org/ecolandtech/SoilWiki/message-archives/composttea+soilfoodweb+soilquality/2/maillist.html
> Archive 3
> http://www.ibiblio.org/ecolandtech/SoilWiki/message-archives/composttea+soilfoodweb+soilquality/3/maillist.html
> Archive 4
> http://www.ibiblio.org/ecolandtech/SoilWiki/message-archives/composttea+soilfoodweb+soilquality/4/maillist.html
> Archive 5
> http://www.ibiblio.org/ecolandtech/SoilWiki/message-archives/composttea+soilfoodweb+soilquality/5/maillist.html
> \|/
> =
> /|\
> Gardening Hand Tool Sourcelist
> (needs revising)
> http://www.ibiblio.org/ecolandtech/documents/gardening-hand-tools.faq
> Soil and Health Library
> http://www.soilandhealth.org/index.html
> \|/
> =
> /|\
> Glomalin: Hiding Place for a Third of the World's Stored Soil Carbon
> http://www.ars.usda.gov/is/AR/archive/sep02/soil0902.htm
> 
> Glomalin, extracted from
> undisturbed Nebraska soil and
> then freeze-dried.
> (K9969-2)
> 
> A sticky protein seems to be the unsung hero of soil carbon storage.
> 
> Until its discovery in 1996 by ARS soil scientist Sara F. Wright, this
> soil "super glue" was mistaken for an unidentifiable constituent of soil
> organic matter. Rather, it permeates organic matter, binding it to silt,
> sand, and clay particles. Not only does glomalin contain 30 to 40
> percent carbon, but it also forms clumps of soil granules called
> aggregates. These add structure to soil and keep other stored soil
> carbon from escaping.
> 
> As a glycoprotein, glomalin stores carbon in both its protein and
> carbohydrate (glucose or sugar) subunits. Wright, who is with the
> Sustainable Agricultural Systems Laboratory in Beltsville, Maryland,
> thinks the glomalin molecule is a clump of small glycoproteins with iron
> and other ions attached. She found that glomalin contains from 1 to 9
> percent tightly bound iron.
> A microscopic view of an arbuscular mycorrhizal fungus: Click here for
> full photo caption.
> A microscopic view of an
> arbuscular mycorrhizal fungus
> growing on a corn root. The
> round bodies are spores, and
> the threadlike filaments are
> hyphae. The substance coating
> them is glomalin, revealed by
> a green dye tagged to an
> antibody against glomalin.
> (K9968-1)
> 
> Glomalin is causing a complete reexamination of what makes up soil
> organic matter. It is increasingly being included in studies of carbon
> storage and soil quality. In fact, the U.S. Department of Energy, as
> part of its interest in carbon storage as an offset to rising
> atmospheric carbon dioxide (CO2) levels, partially funded a recent study
> by lab technician Kristine A. Nichols, a colleague of Wright's. Nichols
> reported on the study as part of her doctoral dissertation in soil
> science at the University of Maryland.
> 
> That study showed that glomalin accounts for 27 percent of the carbon in
> soil and is a major component of soil organic matter. Nichols, Wright,
> and E. Kudjo Dzantor, a soil scientist at the University of
> Maryland-College Park, found that glomalin weighs 2 to 24 times more
> than humic acid, a product of decaying plants that up to now was thought
> to be the main contributor to soil carbon. But humic acid contributes
> only about 8 percent of the carbon. Another team recently used carbon
> dating to estimate that glomalin lasts 7 to 42 years, depending on
> conditions.
> 
> 
> For the study, the scientists compared different chemical extraction
> techniques using eight different soils from Colorado, Georgia, Maryland,
> and Nebraska. They found that current assays greatly underestimate the
> amount of glomalin present in soils. By comparing weights of extracted
> organic matter fractions (glomalin, humic acid, fulvic acid, and
> particulate organic matter), Nichols found four times more glomalin than
> humic acid. She also found that the extraction method she and Wright use
> underestimates glomalin in certain soils where it is more tightly bound
> than usual.
> Soil scientist examines a soil aggregate coated with glomalin: Click
> here for full photo caption.
> In her Beltsville laboratory,
> soil scientist Sara Wright
> examines a soil aggregate
> coated with glomalin, a soil
> protein she identified in 1996.
> (K9972-1)
> 
> In a companion study, Nichols, Wright, and Dzantor teamed up with ARS
> chemist Walter F. Schmidt to examine organic matter extracted from the
> same soils under a nuclear magnetic resonance (NMR) imager. They found
> that glomalin's structure differs from that of humic acid—or any other
> organic matter component—and has unique structural units.
> 
> In a current study in Costa Rica, partly funded by the National Science
> Foundation, Wright is using glomalin levels and root growth to measure
> the amount of carbon stored in soils beneath tropical forests. She is
> finding lower levels of glomalin than expected and a much shorter
> lifespan. "We think it's because of the higher temperatures and moisture
> in tropical soils," she explains. These factors break down glomalin.
> 
> Forests, croplands, and grasslands around the world are thought to be
> valuable for offsetting carbon dioxide emissions from industry and
> vehicles. In fact, some private markets have already started offering
> carbon credits for sale by owners of such land. Industry could buy the
> credits as offsets for their emissions. The expectation is that these
> credits would be traded just as pollution credits are currently traded
> worldwide.
> Soil scientist and technician examine extracted soil organic matter
> constituents: Click here for full photo caption.
> Soil scientist Sara Wright
> (foreground) and technician
> Kristine Nichols use nuclear
> magnetic resonance to examine
> the molecular structure of
> extracted soil organic matter
> constituents.
> (K9971-1)
> 
> How Does Glomalin Work?
> 
> It is glomalin that gives soil its tilth—a subtle texture that enables
> experienced farmers and gardeners to judge great soil by feeling the
> smooth granules as they flow through their fingers.
> 
> Arbuscular mycorrhizal fungi, found living on plant roots around the
> world, appear to be the only producers of glomalin. Wright named
> glomalin after Glomales, the taxonomic order that arbuscular mycorrhizal
> fungi belong to. The fungi use carbon from the plant to grow and make
> glomalin. In return, the fungi's hairlike filaments, called hyphae,
> extend the reach of plant roots. Hyphae function as pipes to funnel more
> water and nutrients—particularly phosphorus—to the plants.
> 
> "We've seen glomalin on the outside of the hyphae, and we believe this
> is how the hyphae seal themselves so they can carry water and nutrients.
> It may also be what gives them the rigidity they need to span the air
> spaces between soil particles," says Wright.
> Technician checks progress of corn plants: Click here for full photo
> caption.
> Technician Kristine Nichols
> checks the progress of corn
> plants growing in containers
> specially designed for
> glomalin production.
> (K9973-1)
> 
> As a plant grows, the fungi move down the root and form new hyphae to
> colonize the growing roots. When hyphae higher up on the roots stop
> transporting nutrients, their protective glomalin sloughs off into the
> soil. There it attaches to particles of minerals (sand, silt, and clay)
> and organic matter, forming clumps. This type of soil structure is
> stable enough to resist wind and water erosion, but porous enough to let
> air, water, and roots move through it. It also harbors more beneficial
> microbes, holds more water, and helps the soil surface resist crusting.
> 
> Scientists think hyphae have a lifespan of days to weeks. The much
> longer lifespan of glomalin suggests that the current technique of
> weighing hyphae samples to estimate fungal carbon storage grossly
> underestimates the amount of soil carbon stored. In fact, Wright and
> colleagues found that glomalin contributes much more nitrogen and carbon
> to the soil than do hyphae or other soil microbes.
> 
> Two rows of dried soil samples: Click here for full photo caption.
> Dried samples of undisturbed
> soil (top row) and material
> left after extractable organic
> matter has been removed
> (bottom row). Although minerals
> are the most abundant components
> of soil, organic matter gives
> it life and health. Soil
> samples from left to right
> are from Maryland, Nebraska,
> Georgia, and Colorado.
> (K9974-1)
> 
> 
> Rising CO2 Boosts Glomalin, Too
> 
> In an earlier study, Wright and scientists from the University of
> California at Riverside and Stanford University showed that higher CO2
> levels in the atmosphere stimulate the fungi to produce more glomalin.
> 
> They did a 3-year study on semiarid shrub land and a 6-year study on
> grasslands in San Diego County, California, using outdoor chambers with
> controlled CO2 levels. When CO2 reached 670 parts per million (ppm)—the
> level predicted by mid to late century—hyphae grew three times as long
> and produced five times as much glomalin as fungi on plants growing with
> today's ambient level of 370 ppm.
> 
> Longer hyphae help plants reach more water and nutrients, which could
> help plants face drought in a warmer climate. The increase in glomalin
> production helps soil build defenses against degradation and erosion and
> boosts its productivity.
> 
> Wright says all these benefits can also come from good tillage and soil
> management techniques, instead of from higher atmospheric CO2.
> 
> "You're in the driver's seat when you use techniques proven to do the
> same thing as the higher CO2 that might be causing global warming. You
> can still raise glomalin levels, improve soil structure, and increase
> carbon storage without the risks of the unknowns in global climate
> change," she says.
> 
> Putting Glomalin to Work
> 
> Wright found that glomalin is very manageable. She is studying glomalin
> levels under different farming and ranching practices. Levels were
> maintained or raised by no-till, cover crops, reduced phosphorus inputs,
> and the sparing use of crops that don't have arbuscular mycorrhizal
> fungi on their roots. Those include members of the Brassicaceae family,
> like cabbage and cauliflower, and the mustard family, like canola and
> crambe.
> 
> "When you grow those crops, it's like a fallow period, because glomalin
> production stops," says Wright. "You need to rotate them with crops that
> have glomalin-producing fungi."
> 
> In a 4-year study at the Henry A. Wallace Beltsville (Maryland)
> Agricultural Research Center, Wright found that glomalin levels rose
> each year after no-till was started. No-till refers to a modern
> conservation practice that uses equipment to plant seeds with no prior
> plowing. This practice was developed to protect soil from erosion by
> keeping fields covered with crop residue.
> 
> Glomalin went from 1.3 milligrams per gram of soil (mg/g) after the
> first year to 1.7 mg/g after the third. A nearby field that was plowed
> and planted each year had only 0.7 mg/g. In comparison, the soil under a
> 15-year-old buffer strip of grass had 2.7 mg/g.
> 
> Wright found glomalin levels up to 15 mg/g elsewhere in the Mid-Atlantic
> region. But she found the highest levels—more than 100 mg/g—in Hawaiian
> soils, with Japanese soils a close second. "We don't know why we found
> the highest levels in Hawaii's tropical soils. We usually find lower
> levels in other tropical areas, because it breaks down faster at higher
> temperature and moisture levels," Wright says. "We can only guess that
> the Hawaiian soils lack some organism that is breaking down glomalin in
> other tropical soils—or that high soil levels of iron are protecting
> glomalin."
> 
> It's Persistent and It's Everywhere!
> 
> The toughness of the molecule was one of the things that struck Wright
> most in her discovery of glomalin. She says it's the reason glomalin
> eluded scientific detection for so long.
> 
> "It requires an unusual effort to dislodge glomalin for study: a bath in
> citrate combined with heating at 250 °F for at least an hour," Wright
> says. "No other soil glue found to date required anything as drastic as
> this."
> 
> "We've learned that the sodium hydroxide used to separate out humic acid
> in soil misses most of the glomalin. So, most of it was thrown away with
> the insoluble humus and minerals in soil," she says. "The little bit of
> glomalin left in the humic acid was thought to be nothing more than
> unknown foreign substances that contaminated the experiments."
> 
> Once Wright found a way to capture glomalin, her next big surprise was
> how much of it there was in some soils and how widespread it was. She
> tested samples of soils from around the world and found glomalin in all.
> 
> "Anything present in these amounts has to be considered in any studies
> of plant-soil interactions," Wright says. "There may be implications
> beyond the carbon storage and soil quality issues—such as whether the
> large amounts of iron in glomalin mean that it could be protecting
> plants from pathogens."
> 
> Her recent work with Nichols has shown that glomalin levels are even
> higher in some soils than previously estimated.
> 
> "Glomalin is unique among soil components for its strength and
> stability," Wright says. Other soil components that contain carbon and
> nitrogen, as glomalin does, don't last very long. Microbes quickly break
> them down into byproducts. And proteins from plants are degraded very
> quickly in soil.
> 
> "We need to learn a lot more about this molecule, though, if we are to
> manage glomalin wisely. Our next step is to identify the chemical makeup
> of each of its parts, including the protein core, the sugar
> carbohydrates, and the attached iron and other possible ions." Nichols
> is starting to work on just that.
> 
> "Once we know what sugars and proteins are there," says Nichols, we will
> use NMR and other techniques to create a three-dimensional image of the
> molecule. We can then find the most likely sites to look for iron or
> other attached ions.
> 
> "Researchers have studied organic matter for a long time and know its
> benefits to soil. But we're just starting to learn which components of
> organic matter are responsible for these benefits. That's the exciting
> part of glomalin research. We've found a major component that we think
> definitely has a strong role in the benefits attributed to organic
> matter—things like soil stability, nutrient accessibility, and nutrient
> cycling."
> 
> As carbon gets assigned a dollar value in a carbon commodity market, it
> may give literal meaning to the expression that good soil is black gold.
> And glomalin could be viewed as its golden seal.—By Don Comis,
> Agricultural Research Service Information Staff.
> 
> This research is part of Soil Resource Management, an ARS National
> Program (#202) described on the World Wide Web at
> http://www.nps.ars.usda.gov.
> 
> Sara F. Wright and Kristine A. Nichols are with the USDA-ARS Sustainable
> Agricultural Systems Laboratory, Bldg. 001, 10300 Baltimore Ave.,
> Beltsville, MD 20705; phone (301) 504-8156 [Wright], (301) 504-6977
> [Nichols], fax (301) 504-8370.
> 
> 
> "Glomalin: Hiding Place for a Third of the World's Stored Soil Carbon"
> was published in the September 2002 issue of Agricultural Research 
> magazine.
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