Wealden Times | WT166 | December 2015 | Interiors supplement inside

Earth
Matters
Jo Arnell reminds us of the importance of garden soil
This isn’t a very festive topic, I know, but I’ve just
discovered – in the nick of time, that 2015 is the
International Year of Soil. This should have been
headline news – street parties held, allotments hailed, earthy
celebrations enjoyed. Oh well, every year is a year of soil
to gardeners, as we struggle to manage it, improve it and
remove it from under our fingernails. It’s not just gardens
that need soil, either – there’s a growing body of evidence
that says that people need it too. In fact, connection with
the soil is implicated in the prevention of allergies, asthma
and some mental disorders. There are some very good
reasons why we should all be getting down and dirty.
Soil creatures great and small
We all know about earthworms and how good they are for
the soil, incorporating dead and decaying matter, aerating
and generally improving things. The well-known worm
appreciator Charles Darwin once wrote: “It may be doubted
whether there are many other animals which have played so
important a part in the history of the world, as have these
lowly organised creatures.” But, just as vital to soil, plant
and ultimately our health, are billions of microscopic soil
organisms. Get this – just one spoonful of soil contains more
FreeImages.com/Andrew Richards
microorganisms than there are people on the earth. Don’t rush
to wash your hands (again) – some of them are good for us.
Micorrhizae and soil bacteria
Gardeners have lately been introduced to the benefits of a
substance containing Micorrhizae – tiny fungi that form
mutualistic associations with plant roots, helping plants to
obtain nutrients that they can’t otherwise access, in return
for sugars and minerals. Sprinkling a powder containing
the mycorrhizae directly on to plant roots when planting
will help them to establish and grow more strongly.
Bacteria are found in vast numbers in the rhizosphere (the area
around the roots of plants) and their actions work in a similar
way to the beneficial bacteria within the digestive systems
of animals. One group, called Rhizobia, live in symbiosis
with leguminous plants (peas, beans, lupins) in root nodules.
These fix atmospheric nitrogen and make it available to the
plant in return for shelter and sugar (sounds familiar).
Some bacteria are pathogens to be avoided, but many, like
the rhizobia, are vital to plant health, and the rest we have
no clue about, as only five per cent of the bacteria in soil has
been identified as yet. It’s becoming clear that there are huge
implications for the health of our planet in the microbiome,
and the more we’re discovering about this darkly mysterious
world, the more interesting it’s getting. It’s already known
that children playing outside and interacting with the soil
are much less likely to develop allergies and other immune
system disorders, and now scientists have discovered that
being near to one particular bacterium, Mycobacterium
vaccae, could even help cure depression, causing us to produce
serotonin, the hormone that improves our mood. Before
we rush out for a mood enhancing mud bath though,
there’s some soil improvement to be considered.
FreeImages.com/Mike Berg
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