Mycorrhizal Magic

Mycorrhizal Magic

The creature most often missing in agricultural soils is a fungus that burrows into the crop roots. This usually evokes images of an undesirable parasite but this is not a disease organism. Once this creature is locked into a food source from the plant, it gives far more than it receives. In fact, that flow of root sugars is repaid handsomely. The soil, the other root zone microbes, the plant, your livestock, your family and the planet are all beneficiaries of this exchange. This generous life force is called Mycorrhizal fungi and it has become an unfortunate casualty of extractive agriculture. Fungicides, herbicides, acid phosphates, salt fertilisers, nematicides, fallow periods, compaction, erosion and tillage all take their toll, to the point that many soil life analyses reveal serious decimation of this essential symbiont.

Ancient Heroes

There are two forms of Mycorrhizal fungi, one that surrounds the plant roots and another that physically attaches to the roots. In both cases they harvest sugar exudates from the plant. Ectomycorrhizal organisms form a fine spidery web around each root and they are limited to conifers and some hard woods. However, the more intrusive of the pair is much more prevalent. Endomycorrhizal fungi should be found attached to the roots of over 80% of crops. They were originally called VAM (vesicular arbuscular mycorrhiza) but their classification was recently changed to AM or AMF (arbuscular Mycorrhizal fungi). Their maze of hyphae filaments effectively increases the original surface area of the roots by up to 1000% with a remarkably productive outcome. Root benefits are magnified tenfold and the plant is perfectly positioned to achieve its true genetic potential. The only plants that do not attract Mycorrhizal colonisation are brassicas and the chenopods. Brassicas release chemical exudates that repel nematodes and these same chemicals also discourage AM Fungi. Chenopods flourish in salty or alkaline soils and include saltbush, sugar beet and spinach.

AM create structures within root cells called arbuscules that facilitate the transfer of nutrients between the plant and the fungus. […] It is now acknowledged that these compromised creatures may be the single most important tool available to reverse global warming. Over 30% of the offending CO2 in the atmosphere originated from the soil due to the massive humus loss since the Industrial revolution (470 thousand million tonnes). In 1996, a researcher called Sara F. Wright, discovered glomalin, a sticky substance produced by mycorrhizal fungi that generates stable humus in the soil. It is apparent that the decline in humus mirrors the decline in AM in our soil and now we understand why!

The Humus Imperative

Soils are carbon sinks with more potential to keep carbon out of the atmosphere than plant biomass. […] Carbon is stored in biomass for an average of ten years but that critical storage time extends to forty years when it is stored in the soil as stable humus. The principal producers of stable carbon are Mycorrhizal fungi and glomalin is a huge player.  This substance is produced by Glomales, the taxonomic order of which AMF are a part. These fungi use sugar exudates (carbon) from the plant (carbon) to make glomalin. This remarkable material permeates organic matter, binding it to silt, sand and clay particles in the soil. The substance itself contains 40% carbon but it also creates aggregates that stabilize carbon in the soil and prevent its return to the atmosphere as part of the carbon cycle. As a glycoprotein glomalin stores carbon in both its protein and carbohydrate sub-units.  Glomalin contributes much more nitrogen and carbon to the soil than do hyphae or other soil microbes.  Glomalin contains 1-9% tightly bound iron and researchers wonder whether these large amounts of iron could be protecting the plants from pathogens.

Research now suggests that glomalin accounts for over one third of the stored carbon in the soil and that carbon remains in the soil for four decades! It is not too difficult to imagine a time in the near future where there will be legislation protecting these critically important, humus-building organisms. Unfortunately, much of modern agriculture involves practices that compromise AM fungi. This is one of many reasons why biological agriculture is the shape of the future. […]

To read the full article, please go to http://www.nutri-tech.com.au/blog/2011/04/mycorrhizal-magic-–-new-biological-breakthrough/

Reprinted with kind permission from Graham Sait, Nutri-Tech Solutions, Australia.