Healthy soil and sustainable growing

["TradingPostPaul" <tradingpost@riseup.net>]

Some gems from Michael Melendrez website - some of the point's I've been
stressing for months, and a lot more. I strongly recommend reading the
whole thing. I might add that the critical mycorrhizal connection is
something that's been discussed in organic circles since Sir Albert
Howard's work back in the 1930's. Which is where I happened on it
originally ... 

paul, tradingpost@riseup.net
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Soil Ecology & The Soil Food Web
http://www.soilsecrets.com/SoilEcologyandtheSoilFoodWeb.pdf
Or you can read it as html without Adobe reader at
http://66.102.7.104/search?q=cache:6eoYwl9Bs1sJ:www.soilsecrets.com/Soil%252
0Ecology%2520and%2520the%2520Soil%2520Food%2520Web.pdf+glomalin+humus+produc
tion&hl=en&gl=us&ct=clnk&cd=8&client=firefox-a


Organic fertilizers, like composts and manure, have nutrients stored in the
organic matter. The beneficial microorganisms are fed as the nutrients are
slowly released to plants. Adding incorganic fertilizers supplies nutrients
but does not feed microorganisms. The microorganisms decline in numbers
and, since they aren't there in sufficient numbers to release nutrients
stored in organic matter, the plants become even more dependent on repeated
applications of fertilizer nutrients. 

What Happens to Plants Without a Functioning Soil Food Web?
Disease organisms are not suppressed; and therefore multiply and threaten
plants. The loss of symbiosis with soil microorganisms results in reduced
ability to take up water and nutrients. Not only are plant growth adversely
affected but resistance to temperature and moisture stress is reduced as
well. 

Mycorrhizae

Vesicular-arbuscular mycorrhizal (VAM) fungi are very important for most
plants because they hellp plants scavenge for water and nutrients in the
soil. Studies have shown, so far, that over 90% of all plant species form a
symbiotic association with mycorrhizae in natural soils. After the
mycorrhizae "infect" the plant roots, the plants feed the mycorrhizae. The
mycorrhizae benefit plants by sending mycelial threads far out into the
soil, penetrating the spaces too small for plant roots. These threads
capture water and plant nutrients that were not available to plant roots.
The greater nutrients use efficiency that result means that fertilization
requirements go way down. In addition, your plants can tolerate drought a
lot better if they are mycorrhizal, because mycorrhizae also bring in
water. ... Studies have also shown that if soil nutrient levels are very
high, due to regular chemical fertilizer additions, the plants will not
form the symbiotic association with VAM fungi. Because of this, they become
dependent on regular and frequent watering and fertilization to continue
living and growing. 

The Glomus genus of Mycorrhiza fungi living on plant roots, use the plants
carbon to produce glomalin. 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. 

Mycorrhizal fungi play an important role in disease suppression. These
fungi wrap its mesh of hyphae around the root system, so root-feeding
nematodes can't penetrate the network. In addition, mycorrhizal fungi
secrete compounds that are antibiotic and inhibitory to many pathogenic
microbes. 

Organisms That Build Soil Structure

Good soil structure allows for water, mineral nutrients and air to move to
the plants easily. Both bacteria and fungi improve soil structure. Bacteria
produce glues that attach to soil colloidal surfaces, causing the small
particles to stick together. Fungi grow hyphae strands around soil
particles and groups of soil particles, binding them together into what are
called microaggregates. Soils high in microaggregates have a loose, crumbly
structure - like earthworm casts. In the spaces between the "clumps" of
soil particles, water and air can penetrate, and plant roots grow down
between the clumps. In addition, larger organisms like nematodes,
earthworms, millipedes and other arthropods create passages for air, water
and roots as they push through the soil. But these organisms are sensitive
and easily disturbed by pesticides and heavy fertilizer additions.
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