The Science of Soil Health: Cycle, Re-cycle, Repeat


[Music] [Music] If your reductionist science background is anything like mine,
you’re probably imagining soil carbon as individual atoms
either laying or bouncing around the soil and nothing could be further from the
truth. I met with doctor Will Brinton who was
able to give us a more holistic picture on the subject. “I tell people there’s no
such thing in soil as “C”, carbon. It doesn’t exist as carbon! It exists as organic matter from
once-living material, detritus that’s decomposing and you can’t see it here but there’s
humus all through here that has carbon in it. Fifty percent of
humus is carbon the rest is hydrogen, oxygen and some
minerals, nitrogen in particular, and then phosphorus and a little sulfur – bound up in this complex molecule but here’s what I’m saying about carbon
it’s really you have to see it in the active
sense of being carbon dioxide. Well when I say carbon dioxide, you’re saying “oh this CO2 in the in the air” and that’s what all the climate change discussion is about but these soils are producing CO2 from the carbon. It’s not a chemical
reaction it’s a biological process. Microorganisms are feeding on this organic matter right
here and turning it into nutrients for the body and releasing the “C” as CO2 which is coming up here, diffusing up
through the soil. The beauty of the CO2 relationship is
that what’s the primary requirement
of a growing plant that absorbs sunlight? It’s gonna be carabon – carbon dioxide. That’s correct. Without the carbon dioxide no sugars are formed and the whole
infrastructure plant metabolism doesn’t happen so we naively think oh plants are just
getting the CO2 from the air but if you think
dynamically, the CO2 is coming from soil and this is a great canopy here to show
it these are rich soils there’s a high activity we’ve
measured the respiration rate in this soil – we can
quantify that now as CO2 per acre that’s what’s getting really exciting! This plant canopy has a very high CO2 demand during full growth probably in the order a fifty to a
hundred pounds of CO2 per day while these radish plants are at full growth. Where’s the CO2 come from? Well, isn’t it convenient its being produced
right here in the soil? and it’s bubbling up out of the soil so
to speak by capillary and diffusion going past the water
molecules and soil particles and the plant leaves are grabbing and
recycling it immediately so the humus was humus one minute next hour CO2, another hour later its
synthesized sugar in the plant and its on its way back down into the
soil. Carbon dioxide requirements can be
quantified and I believe we will find that there’s
evidence that canopies during full growth are CO2-limited in what that
means is photosynthesis saturates out early so the plant can’t
take up nitrogen if the CO2 isn’t there commensurate to meet the
requirement of the metabolism ’cause taking up nutrients is a
metabolically depleting process – it’s not a passive
process, so it’s a whole system. And I think as we begin to quantify CO2
we’re gonna have some astonishing discoveries here in terms are crop yield limitations. Then we’re going to change our farming practices to be carbon-oriented. ‘Cause it’s not just N-P-K, it’s its C-N-P-K. That’s the difference. [Music] [Music] [Music] [Music]

7 thoughts on “The Science of Soil Health: Cycle, Re-cycle, Repeat

  1. This a great video! Take a look at www.comet-farm.com to see how changes in soil and crop management can reduce greenhouse gas and increase carbon in the soil.

  2. Great video; but it neglects the role of organic matter in the soil beyond supplying CO2 to the growing plant as it reenters the atmosphere from the soil; the risk here is that this video undermines the understanding in the public imagination of the enormous potential for sequestration of atmospheric C as soil humus and other occluded soil carbon, with all of the attendant benefits, including improved soil water and nutrient holding capacity, improved soil tilth, etc.  Perhaps follow up with a video on how some CO2 taken up by the plant is diverted to the soil, drives soil ecological processes, and can become bound within the soil matrix for long periods of time…

    thank you!

  3. Early critics of biochar soil amendments cited increased soil CO2 respiration rates as a negative aspect of biochar's strength as a carbon sink.  As this video explains CO2 soil emissions are not synonymous with CO2 from smoke stacks & tail pipes.

    Increased soil respiration is part and parcel for increased photosynthesis, increased yields and increased root exudates. CO2 struggling past a plant canopy of hungry stomata is a horse of a different color to that released at hundreds of feet or over hot asphalt.

    Isotopic study of Carbon can diferentiate fossil CO2 from young biomass generated CO2. Petroleum-engineers from Conoco accused CoolPlanet Biofuels of adding fossil fuels to their Bio-Gasoline because of it's very high octane levels, but after Isotopic analysis of C-14, Conoco had to eat their hat. (The half-life of carbon-14 is 5,730 years)

  4. One correction However;

    There is very recalcitrant Pyrolitic Carbon in soils. In fact the % of this charcoal, (or now called Biochar when in soils), has been reappraised;
    Demonstration, Using quantitative 13C nuclear magnetic resonance (NMR) spectroscopy measurements, concluding that both Terra Preta Soils and Midwest dark soils contain 40% to 50%+ of their organic carbon (SOC) as pyrolytic carbon char, that this pyrolytic carbon can account for all CEC

    Abundant and Stable Char Residues in Soils:
    Implications for Soil Fertility and Carbon Sequestration;
     J.-D. Mao,, J. Lehmann, 2012, American Chemical Society
    http://pubs.acs.org/doi/abs/10.1021/es301107c

    Given the new findings about electron shuttling & chars, that pyrolitic carbons constitute 40-50% of SOC in dark soils, plus all the new work in microbiology in general over the last few years, chemical plant/microbe signaling comunications,  finding geobacters that eat electrons, metals like uranium & Hg, grow nano-wires forming true soil micro-grids and meta-genomic study & characterization of the wee-beastie worlds that soil food web advocates of humus & composting would be happy that such windows to their worlds are opening so wide.

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