Surrey Homes | SH14 | December 2015 | Interiors supplement inside

Earth
Matters
Jo Arnell reminds us of the importance of garden soil
FreeImages.com/Mike Berg
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. 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 only gardens that need soil, either – there’s a
growing body of evidence that says that people need it too;
connection with the soil is implicated in the prevention
of allergies, asthma and some mental disorders.
no clue about, as only 5 per cent of the bacteria in soil has been
identified. There are huge implications for the health of our
planet in the micro biome, and the more we’re discovering about
this mysterious world, the more interesting it’s getting. Children
playing outside and interacting with the soil are much less
likely to develop allergies and other immune system disorders,
and scientists have discovered that being near to the bacterium,
Mycobacterium vaccae, could reduce depression, causing us
to produce serotonin, the hormone that improves our mood.
Soil creatures great and small
We all know that earthworms are good for the soil,
incorporating dead and decaying matter, aerating and
generally improving things. 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.” Just as vital
to soil, plant and our health, are billions of microscopic,
soil organisms. Get this – just one spoonful of soil contains
more microorganisms than there are people on earth.
Know your soil
Understanding your soil will give you an indication of what
is going to thrive in your plot. There are several types of soil,
derived from particles of the rocks from which they’re formed:
sand, clay, silt, chalk and peat being the main ones. Then
there’s the acidity level which, combined with soil type, will
determine which plants will grow happily. You can buy soiltesting
kits that show how acid or alkaline your soil is (most
hovers around the neutral mark), but you can easily test soil
with your hands, or a jam jar filled with soil and water.
Micorrhizae and soil bacteria
Gardeners have recently been introduced to the benefits
of Micorrhizae – tiny fungi that form mutualistic
associations with plant roots, helping plants to obtain
nutrients that they can’t otherwise access. Sprinkling a
powder containing the mycorrhizae on to plant roots
when planting will help them to establish and grow.
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.
Some bacteria are pathogens to be avoided, but many, like
the Rhizobia, are vital to plant health, and the rest we have
Clay soil
Clay is fertile and tends to be slightly alkaline, which many
vegetables – especially brassicas – appreciate. The main problem
is that it is hard to work, it’s claggy through the winter, slow
to warm in spring, and is like concrete until the autumn. To
improve clay soil, keep adding organic matter and grit. Clay
and silty soils can be prone to forming ‘pans’ of compacted
soil, leading to problems with drainage and poor penetration of
roots. If your soil is compacted, you will need to dig down and
break up the compacted areas and incorporate organic matter –
whether this is compost, manure or spent mushroom compost.
Sandy soil
This is lovely and easy to work, fast to warm, so the season
can start earlier. The problem with this type of soil, however,
is that it is very free-draining, so water and the precious
nutrients dissolved in it leach quickly out of the soil, leaving
93 www.wealdentimes.co.uk