Our Indispensable Soil - Soil: Reflections on the Basis of our Existence - page 7

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Nutrient-poor sand . Grains of sand on the beach easily blow inland on the wind. Farmers in the
southern Swedish provinces of Sk￥ne and Halland suffered major problems in the mid-sixteenth cen-
tury when nutrient-poor coastal sand caked their fields. One of the reasons for this erosion was the
practice of using seaweed as fertiliser, which depleted growing conditions for plants such as European
beachgrass and lyme grass ( pictured ), weakening their ability to hold the sand in place. Human popu-
lation growth further increased the pressure on beachside vegetation and the problems persisted until
the nineteenth century, when large-scale planting of pine trees took place along the coast

Desertification in Africa

One might imagine that the ability of fungi to bind soil particles together could
come in handy in areas susceptible to erosion—so long as one uses plants that
attract the right sort of fungi. The Swedish International Development Cooperation
Agency (Sida) liked the idea and sent me on a reconnaissance trip to Tunisia,
where desertification has increased due to the felling of acacia trees. So I packed
my bags with test tubes and soil collection equipment and headed for the airport.
The first African I met was a young Tunisian fellow passenger on the flight to
Tunis. A student at Chalmers University of Technology in Gothenburg, he told me
Sweden was clean and well ordered compared to his country, where rubbish lines
the streets. But he was proud of his roots and invited me to meet his family in
Tunis, promising that his grandmother's couscous was altogether superior to the
precooked variety one buys in Sweden. Unfortunately, I had to decline this gener-
ous offer as I needed to travel south into the desert, but I told him about my fungi
and how I hoped they could help to combat erosion. As we bade each other a warm
goodbye at Tunis airport I tried to picture a young Swede inviting a stranger from
North Africa home to taste his mother's pickled herring or his father's aquavit.
After clearing customs I was met by Hafedh Nasr, North Africa's leading expert
on mycorrhiza, with whom I was to investigate how symbiotic fungi might combat
soil erosion in the savannah forests on the edge of the Sahara. The acacias in this
region are highly resistant to drought, their roots capable of reaching water forty
metres beneath the surface. The trees once served as a natural buffer against desert
encroachment, but most have been cut down to provide food for livestock and fire-
wood for a rapidly increasing local population. Many were destroyed during fight-
ing between Allied and German and Italian troops during World War II and the
forests today are little more than a scattered vestige of a bygone era.
Windblown sand due to inadequate vegetation is a problem not only in the
Sahara. The southern Swedish province of Sk￥ne suffered similarly in the early
twentieth century, when sand blown inland from beaches rendered arable land
infertile. The pine plantations along the coast today testify to how the authorities
solved the problem then.
History is littered with examples of how people have been forced to flee infer-
tile land. In The Grapes of Wrath and East of Eden , John Steinbeck relates how
farmers in America's Midwest abandoned their homesteads and relocated to
California when the soil on their land was blown away during a period of severe
drought in the 1930s. The Midwestern prairie is especially susceptible to wind
erosion and giant dust bowls darkened the skies as far away as New York. The