Glomalin in the soil

Discussion in 'Organic Lawn Care' started by ICT Bill, Jun 17, 2008.

  1. ICT Bill

    ICT Bill LawnSite Platinum Member
    Messages: 4,115

    I had heard of this but had not seen a good explanation like this is. This comes from . I would think if you could come up with a cheap test to see if it is in the soil it would be a good indicator of soil health, if its there and in good numbers you must be doing something right.

    A soil constituent known as glomalin provides a secure vault for the world's soil carbon. That’s according to Kristine Nichols, a microbiologist at the Agricultural Research Service (ARS) Northern Great Plains Research Laboratory in Mandan, N.D.

    Glomalin is a sticky substance secreted by threadlike fungal structures called hyphae that funnel nutrients and water to plant roots. Glomalin acts like little globs of chewing gum on strings or strands of plant roots and the fungal hyphae. Into this sticky “string bag” fall the sand, silt and clay particles that make up soil, along with plant debris and other carbon-containing organic matter. The sand, silt and clay stick to the glomalin, starting aggregate formation, a major step in soil creation.

    On the surface of soil aggregates, glomalin forms a lattice-like waxy coating to keep water from flowing rapidly into the aggregate and washing away everything, including the carbon. As the builder of the formation “bag” for soil, glomalin is vital globally to soil building, productivity and sustainability, as well as to carbon storage.

    Nichols uses glomalin measurements to gauge which farming or rangeland practices work best for storing carbon. Since glomalin levels can reflect how much carbon each practice is storing, they could be used in conjunction with carbon credit trading programs.

    In studies on cropland, Nichols has found that both tilling and leaving land idle--as is common in arid regions--lower glomalin levels by destroying living hyphal fungal networks. The networks need live roots and do better in undisturbed soil.

    When glomalin binds with iron or other heavy metals, it can keep carbon from decomposing for up to 100 years. Even without heavy metals, glomalin stores carbon in the inner recesses of soil particles where only slow-acting microbes live. This carbon in organic matter is also saved, like a slow-release fertilizer, for later use by plants and hyphae.

    Nichols began her career with ARS working with soil scientist Sara Wright, who first discovered and named glomalin in 1996. Wright has since retired.

    Nichols will present these research results this afternoon at a public field day in Brookings, S.D.
  2. ICT Bill

    ICT Bill LawnSite Platinum Member
    Messages: 4,115

    Something else very interesting that I found at

    Vegetation and Arbuscular Mycorrhizal Fungi Since AM fungi produce glomalin, soil stocks of glomalin may be indirectly infl uenced by factors that control AM growth. Globally, AM fungi are most abundant where standing lengths of fi ne roots and host plant availability are greatest (Treseder and Cross, 2006). This pattern is consistent with the notion that photosynthetic rates should determine absolute amounts of C available for AM fungi (Harris and Paul, 1987; Harris et al., 1985; Johnson et al., 2002). Inorganic
    Resources and Arbuscular Mycorrhizal Fungi
    Plants often allocate more C to their AM symbionts when plant growth is limited by soil nutrients (Read, 1991; Treseder, 2004). For example, N and P fertilization often reduces AM growth (e.g., Mosse and Phillips, 1971; Treseder, 2004) because nutrient limitation is alleviated. Conversely, elevated atmospheric CO2 consistently increases AM abundance (e.g., O’Neill et al., 1987; Staddon and Fitter, 1998; Treseder, 2004), either because plants are more N or P limited, photosynthate is more readily available, or both (Read, 1991). Abundance of AM fungi also tends to be greatest when water availability is low, possibly owing to increased investment by plants in AM fungi to improve water status (Auge, 2001). Arbuscular mycorrhizal fungi increase water use effi ciency in plants more often (Al-Karaki and Clark, 1999; Cui and Nobel, 1992; Di and Allen, 1991; Honggang et al., 1989; Ruiz-Lozano and Azcon, 1995; Ruiz-Lozano et al., 1995a, 1995b; Sieverding, 1979, 1981) than not (Koide and Li, 1991; Sieverding, 1979), and this effect has been attributed to improved P nutrition in host plants (Auge, 2001). In general, both the availability of host plant photosynthate and the degree to which it is allocated to AM fungi appear to determine the distribution of AM fungi within and among ecosystems.
  3. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    Glomalin: The Real Soil Builder
    By Don Comis
    February 5, 2003

    An Agricultural Research Service scientist now has more proof that she has found a key ingredient responsible for the well-known benefits of soil organic matter.
    Sara F. Wright, a soil scientist with the ARS Sustainable Agricultural Systems Laboratory in Beltsville, Md., discovered glomalin in 1996 and named the substance after Glomales, the taxonomic order of the fungi that produce the sticky protein. Recently, she used a nuclear magnetic resonance imager to show that glomalin is structurally different from any other organic matter component, proving it is a distinct entity.
    The fungi live on most plant roots and use the plants' carbon to produce glomalin. Glomalin is thought to seal and solidify the outside of the fungi's pipe like filaments that transport water and nutrients to plants.
    As the roots grow, glomalin sloughs off into the soil where it acts as a "super glue," helping sand, silt and clay particles stick to each other and to the organic matter that brings soil to life. It is glomalin that helps give good soil its feel, as smooth clumps of the glued-together particles and organic matter flow through an experienced gardener's or farmer's hands.
    Glomalin was long lost in humus, the organic matter that is often called "black gold." When it did turn up in humus measurements, it was thought to be a contaminant.
    Glomalin is not just the glue that holds humus to soil particles, it actually does much of what humus has been credited with. Because there is so much more glomalin in the soil than humic acid, an extractable fraction of humus, glomalin stores 27 percent of total soil carbon, compared to humic acid's eight percent. It also provides nitrogen to soil and gives it the structure needed to hold water and for proper aeration, movement of plant roots and stability to resist erosion.
    ARS is the U.S. Department of Agriculture's chief scientific research agency.
  4. JDUtah

    JDUtah LawnSite Silver Member
    from UT
    Messages: 2,636

    INteresting.... Any simple tests for it?
  5. treegal1

    treegal1 LawnSite Gold Member
    Messages: 3,911

    Glomeraceae, is the way we where told it was spelled. and to store carbon in the soil is a little more involved, there are several AM that can secrete. As a glycoprotein, glomalin stores carbon in both its protein and carbohydrate (glucose or sugar) subunits. Most research on glomalin-related soil proteins (GRSP) has focused on the role of arbuscular mycorrhizal fungi in soil aggregation and environmental about we test for chitins, ergosterol and Glomalin in balances to quantify the glomalin based on the total.

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