Floral Splendour and Shortage of Nutrients - Soil: Reflections on the Basis of our Existence - page 48

better known for explaining the nature of the Aurora borealis . Most spectacu-
larly, he also invented an electromagnetic cannon with a range far exceeding the
howitzers of the day and which, Birkeland claimed, was also silent when fired.
When Birkeland demonstrated this wizardry at the Oslo University banquet hall
in 1903, an almighty roar filled the air when he turned on the electricity. The
accompanying flash of light sent the audience scattering in panic. Birkeland
himself was delighted, calling it the most dramatic moment in his life and later
remarking that “the projectile shot down my shares from a value of three hun-
dred kroner to zero, but hit its target perfectly”. This was because he had realised
that atmospheric nitrogen reacted with oxygen during the release of energy from
the flash of light. It was well known by then that nitrate was created in this way
when a lightning bolt hit the ground, and Birkeland realised his cannon could
be developed into an oven to make artificial fertiliser. Such a venture would be
energy-intensive so Birkeland teamed up with an industrial magnate who bought
one of Norway's waterfalls, Rjukanfallet, to build a hydropower dam. During the
course of twelve months they manufactured a couple of kilograms of artificial
fertiliser. Of course, this did not get them very far and the oven was a commer-
cial failure. Not until the Haber-Bosch process was invented did it become pos-
sible to manufacture artificial fertiliser on an industrial scale.
Hoofmarks. Livestock grazing and trampling shapes plant communities. Grass withstands graz-
ing because the animals cannot reach all the way down to the leaf buds at the base of the plant.
The buttercup forms substances that cows cannot tolerate and grows commonly in grazed fields.
Grazing also benefits low-growing species that would otherwise be overshadowed by tall grass.
Some species thrive in the disturbed soils trampled by cattle, while others grow unhindered in
thorny thickets the cows cannot reach