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By Julian White of Fertile Farms
There are a number of ways that carbon can store in
the ground, including organic matter recycling and humification; photosynthetic bacteria;
plant sugars and root exudates; phytoliths or plantstones; and
carbonates.
ORGANIC MATTER RECYCLING AND HUMIFICATION
This is probably the first process that comes to mind
when thinking of increasing organic matter. It is certainly the most visual.
Seeing worms and white fungi consuming residues from the previous season is
something we have all experienced at some point. The use of carbon in the
cellulose form by decomposers that break down complex carbon chain molecules to
more simple polymers via the complex microscopic ecosystem that is the soil
food web is the process of humification,
resulting in what has been referred to as the ghost in the machine - humus.
PHOTOSYNTHETIC BACTERIA
A not so talked about process is what could be called
micro-photosynthesis. Research has shown that enormous amounts of carbon can be
generated by photosynthetic bacteria at up to 200 mm of depth. But there is no
light at that depth! Says the healthy scepticism in your mind. Light spectrums
such as UV and IR do energise this depth and power organisms such as purple
non-sulphur photosynthetic bacteria. Phosphorescence or fluorescing bacteria
are also at work here. Herbicides especially Glyphosphate kill off phototropes
and algae in large numbers and most soils as Lab tested by Fertile Farm are
very low in these species. These are the species that continue to function in anaerobic
soil conditions and support the aerobic soil microbes by releasing carbon,
nitrogen and oxygen via their metabolic processes. Photosynthetic bacteria are
found in formulations of EM (Effective Microorganisms) and work in symbiosis
with yeasts, actinomycetes and
lactobacillus bacteria. The Prime Carbon: Soil Enhancement and Carbon
Sequestration Program is unique in incorporating products and practices that
support this process.
PLANT SUGARS AND ROOT EXUDATES
Familiar to those of us in the biological farming
world, plant sugars are the bi product of photosynthesis, and aware of it or
not, is every farmers daily goal of achievement.
C02 + H20 and
sunlight through chlorophyll = C6 H12 O6 or sugar, the basic building block of
all life. Sugars are measured in Brix by a refractometer and readings of over
10 - 12 indicate adequate levels of photosynthetic efficiency. The plant manages
the fruits of its labour wisely and combines some sugars with nitrogen to form
amino acids for proteins some for building more tissue with cellulose and
around 20 -30% of sugars are dumped out in the roots. Why! To feed the microbes
of course! Microbes in the rhizosphere use this custom designed energy source
to make goodies such as enzymes that solubilise nutrients from the unavailable
pool in your soil (have a totals test done with your next soil test to see how
much is there).
This carbon now
forms part of the soil food web and the humification process. It is eventually
combined with other soil minerals and according to the work of Dr Christine
Jones, ends up in the stable fraction of soil carbon.
PHYTOLYTH OR PLANT STONES
Plantstones form as microscopic grains of silica in
plant leaves particularly in grass-based pastures and crops such as sugar cane
and wheat. During plant growth a small proportion of organic carbon becomes
encapsulated within these silica grains. Regardless of whether the plant dies,
burns or is harvested, the carbon entrapped in the plantstone is highly
resistant to decomposition. Therefore, unlike most plant matter which readily
decomposes in soil returning CO2 to the atmosphere, the carbon in plantstones
effectively removes CO2 from the atmosphere for millenia. The rate of phytolith occluded carbon sequestration varies
widely between plant types1 and it is likely that the PhytOC
sequestration rate of many plant types could be increased considerably by
selection or genetic manipulation and agronomic management as this trait has
not been selected for previously. Indeed, the amount of carbon sequestered in
phytoliths as a proportion of that fixed by plants is minor. For example, in
the case of sugar cane, the PhytOC sequestration rate only represents ~0.3% of
the dry above-ground biomass production.
CARBONATES
Sodium, Calcium and Magnesium Bicarbonates are what
cause the yucky white scale on my shower head because we use ground water. Lime
is Calcium carbonate (CaCO3) and is a mineral form of carbon containing only
about 12% carbon. So if you are thinking that liming will increase your soil
carbon, it won't increase it by much. Calcareous soils have the carbonates
dissolved out of them with acid in the lab to give a more accurate soil test
result for total carbon.
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