Photosynthesis, Oxidation & the Energy Equation

  • Kate Tarrant

    04/10/2023 at 10:48 am

    Thanks Mark, fascinating, I have to admit I do find it a bit complicated to wrap my head around the Eh-pH thing but in my view it really does confirm that the principles behind regenerative agriculture are absolutely underpinned by science. For me the key points to note from your article is more about what we do with that science – and that is as you say:

    Firstly, we need to find ways to minimise the use of practices that have an oxidising effect on the soil and/or damage soil life.

    This involves moving towards conservation/minimal/no tillage, biologically considerate nutrition, pest, disease and weed management methods, keeping the soil covered to avoid exposure, etc…

    Simultaneously we must implement strategies that provide soil microbes with more fuel to drive beneficial activity.

    These include the growing of cover crops and interplanting companion species, increasing plant diversity, mulching with organic residue, composting, targeting nutritional applications to optimise photosynthesis, managing grazing to improve pasture growth, etc…

    I did find this review (uploaded to the documents tab in the as well in case the link doesn’t work ) by the same guy (& others) for those that do want to take a deep dive.

    Also if you want to listen to the podcast Mark is referring to check it out here..

  • Andrew Bland

    05/10/2023 at 9:05 am

    Hi Mark, I can not download the doc. Can you please email it to me [email protected] Thanks, Andrew.

    • Lower Blackwood LCDC

      05/10/2023 at 10:58 am

      Andrew if you hover your cursor to the right of the document name you’ll see a download button. But in case not I have uploaded to the documents tab for this group.

  • Laura Stocker

    05/04/2024 at 8:30 am

    Thank you. This is fascinating. The more I learn, the more there is to learn! I’m a bit confused about oxygen in the soil. From what you’re saying it’s not a good thing to have oxygen in the soil because it causes oxidisation. However, we are also told that compacted soil is bad because it excludes air, and we know that loose friable soil is good for plant growth. Can you explain what I’ve misunderstood please? Thank you,


    • Mark Tupman

      16/04/2024 at 12:51 pm

      Hi Laura,

      that’s a great question.

      Firstly, oxygen is definitely needed in the soil for respiring microbiology and plants but we need both good oxygenation and restricted oxygen environments in our soils to support different microbe groups and processes. This happens with good soil aggregation, where air flows freely between the gaps of, but not so much into, soil aggregates.

      Secondly, the amount of energy in our soils is in a state of flux as energy is generated and used. We must ensure that sufficient energy in the form of carbohydrate’s are being generated by plant photosynthesis to fuel good aerobic activity.

      In this case, it’s not really the excess oxygen that’s the root of the problem, it’s the lack of carbohydrate production and we need to try and improve the situation with better plant cover, diversity, growth etc… this is essentially a reduction process which is the opposite of oxidation I.e. energy gain instead of loss.

      What we also need to do is minimise the amount of wasteful oxidation that occurs through practices such as tillage, bare fallow etc…that result in the burning of organic matter (stored energy) that is exposed to excessive oxygen and heat/sunlight, for no biological gain.

      in summation, with things like excess cultivation, overgrazing, herbicide use, lack of adequate plant cover etc… our soils are are subject to wasteful oxidation and low energy supply.

      To strike a balance, we need to make sure organic matter is being produced at a similar or greater rate to what it is being used or else the system starts to go South – organic matter declines, aggregation isn’t maintained, plant growth is compromised, microbial activity subsides and so on.

      • This reply was modified 1 month, 4 weeks ago by  Mark Tupman.
      • Laura Stocker

        19/04/2024 at 6:48 pm

        Thank you. Very clear!

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