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GROWERS INFORMATION -
ARTICLE - LIFE IN THE SOIL |
Life In The Soil
By: Eric Biska
AKA "Ask Eric"
If you want to grow 100% organic, just purchase or brew
organic tea solutions that can be watered into the crop
manually or by drip irrigation. Very few organic solutions
will not clog drippers, so you may want to run spaghetti lines
open-ended, but with very precise control over flow rates, and
the frequency and duration of applications.
When re-using the medium in the raised bed, remove as much
root debris, leaf matter, etc by hand from the soil without
disturbing the hardware cloth. The cloth should keep most of
the roots out of the drainage layer. To further re-loosen the
soil and speed decomposition of old roots, run a small roto-tiller
up and own the bed(s). Be very careful that the tiller blade(s)
are set to the correct depth, and do not ensnare the hardware
cloth. Leech the medium heavily with warm to hot water. If
possible, hook up your lines to a hot water tank, and let it
run for 48 hours through the system. A floor drain that
doesn’t clog is a must for this application. Do not consider
using raised beds for several crops if you are unable to apply
large volumes of water to flush through the raised beds to
wash away salts, residues, etc. Before replanting, you will
need to re-buffer the medium for pH. If using peat-moss add
another 5 to 6 cups of dolomite lime and loosely till into the
soil. For coco, check the pH of the medium before planting and
make any necessary adjustments, although few if any, should be
required. After a healthy crop or two you should have a pretty
good population of microbes working for you in the soil. Most
microbes require a source of carbon, so it’s not a bad idea to
add several liters of worm castings to the medium each
planting. Worm teas are said to be high in carbonic acid. One
veteran grower remarked on re-using their raised beds: “…each
crop just gets better and better…”. To create a complex life
system in your beds, you might consider some of the below as
additions or to learn more about how you can make them work
for you.
Bacillus- several varieties of Bacillus (i.e Bacillus
megaterium) have been found to play a role in the conversion
of unavailable forms of phosphates into plant available forms.
In natural settings they can provide near 10% of the available
phosphorous in the soil solution. With increased levels of
plant available phosphorous, Bacillus strains become less
effective. However, if the Bacillus can sustain as a back up
it may continue to provide hungry blooms with phosphorous if
it should become otherwise unavailable or “locked out”. This
bacterium is of special interest to organic farmers who
incorporate rock phosphate into the growing medium or if
introduced through fertilizer teas, preparations, etc. Rock
phosphate tends to be mostly unavailable, breaking down into
plant available forms over time.
Mychorhizae-This fungus forms a symbiotic relationship with
the plants. The mychorhizae fungi penetrate the plants grow
around the plants root system, effectively increasing the root
surface area available for nutrient absorption. The fungi are
able to transfer phosphorous into the plant, the product of
their digestion of soil materials (nutrients).
Nitrosomonas- Converts plant available ammonium (NH4) to
unavailable nitrite (NO2). In doing so, it acidifies the soil,
which in nature is a means of storing it in the soil for later
use.
Nitrobacter-These bacteria convert the nitrite resulting from
the nitrification into nitrate (NO3-), a potentially available
form of nitrogen.
Rhizobium-A bacteria associated with nitrogen fixation,
usually in legumes. The bacteria form a symbiotic relationship
with the plants, increasing the plant root surface area
available for nutrient absorption. Much of the air we breathe
contains a percentage of inert nitrogen gas (N2). These
bacteria digest the atmospheric nitrogen and feed the plant
nitrogen in a plant available form. In some agricultural field
crops, this is the plants principal provider of nitrogen.
Additions of nitrogen fertilizer can actually inhibit the
performance of these bacteria.
Pseudomonas-another PGRB (plant growth regulating bacteria)
which is associated with the solublization of unavailable
forms of phosphate in the soil.
Streptomyces- Bacteria that secrete a variety of compounds
including antibiotics that prevent and control root zone
pathogens. A closely related species of Streptomyces produces
the antibiotic that we use, streptomycin. Many studies
demonstrate the bacteria’s effectiveness at controlling root
diseases, and select foliar diseases. An interesting
consideration noted in one study is that they will also reduce
levels of some nitrogen fixing bacteria in the soil.
Trichoderma-Strains of Trichoderma bacteria are found
naturally occurring in many soils can play a role in the
prevention and control of root pathogens, ultimately providing
a healthier soil environment which can lead to higher yields.
Some research suggests that the proteins in Trichoderma can
degrade chitin, which is a structural component found in
pathogenic fungi such as powdery mildew and in insects. Some
innovative propagating plugs, growing blocks and materials are
inoculated with strains of Trichoderma. If a healthy soil
environment is maintained, the bacteria will continue to
colonize the roots and multiply in the growing media. The
trichoderma help to form a protective layer around the root
system, helping to fend off invading pathogens, etc.
Urease-an enzyme that plays a role in the conversion of urea
CO(NH2)2 into ammonia which is able to pick up a free hydrogen
ion to become ammonium (NH4), a plant available form nitrogen
which may be absorbed by the plant, stored, or nitrified. Some
organic standards recognize certain grades of urea, as it is a
carbon based source of nitrogen. For most indoor applications
additions of urea are not recommended, unless they are
prepared specifically (usually as a blend) for your
applications. Urea is usually very unstable in the soil
solution, disrupting pH levels, and at worst burning plants
and toxifying the soil. |
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