Can readers help Richard Sibly with research into the sustainability claims made about
methane emissions and soil as a carbon sink?
Regenerative farming is an approach that aims to enable the land, the soil, water,
nutrients and natural assets to regenerate themselves, rather than employ conventional
approaches that can deplete these natural resources.
Two excellent films featuring enthusiastic farmers advocate this approach are Six Inches
of Soil and Rachel’s Farm. The former is available to rent on Amazon Prime the latter is
available on the BBC iPlayer.
There are many good aspects in both these films, but there are a couple of points about
which I was less sure.
One is a claim that - contrary to conventional opinion - ruminants are not responsible for
the methane that exists in the upper atmosphere. In Rachel’s Farm, Rachel attends a
course in which the lecturer, Dr Walter Jehne, asserts that the methane emitted by
ruminants is neutralised in the vicinity of the animals by the hydroxyls, OH, given off by
the surrounding grasses.
Chemistry is not a specialisation of mine, but I have gleaned the following from some
research.
It is generally agreed that OH is a highly reactive gas that acts like an atmospheric
detergent, breaking down methane and other gases. The conventional view is that the
process occurs in the troposphere 6–19 km above the earth’s surface.
In contrast in Dr Jehne’s theory, the process occurs locally before the methane leaves
the vicinity of the cow because there is there an abundance of OH molecules created by
the breakdown by sunlight of water molecules emitted by local plants.
I have tried to find evidence for this theory but there is no scientific paper in the places I
rely on, Google Scholar and Web of Science. Dr Jehne is a scientist who retired from
Australia’s national science agency CSIRO in order to work on regenerative farming, so I
contacted CSIRO to ask them about the theory but have not received a reply.
The other point on which I am seeking input is the claim that when farmed
regeneratively, soil is a continuing carbon sink. I can see this working while the soil is
regenerated and soil carbon levels increase, but long-term, continuing absorption of
carbon would surely require soil levels to rise. Is this something that happens in
practice?
If WCAG newsletter readers can provide any help it would be greatly appreciated. Please
send comments to r.m.sibly@reading.ac.uk
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