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

Geoscience Reference

In-Depth Information

then Czechoslovakia were dying due to acid rain caused by the burning of sul-

phur-containing oil and coal, some scientists feared Swedish forests would suf-

fer the same fate. Acid rain leaches key nutrients such as calcium, potassium and

magnesium from the topsoil, causing many Czechoslovakian spruce trees to die

from a lack of magnesium, a necessary ingredient in chlorophyll and hence essen-

tial for photosynthesis. When I visited the country in the late 1980s I saw large

areas of dead forest in exposed mountainous areas near the German border, while

spruces had fared much better on magnesium-rich serpentine soil. In Sweden we

are lucky because large quantities of magnesium are carried inland on wind from

the sea. Also, we were not as heavily affected by sulphur emissions as former

Czechoslovakia, where vast quantities of sulphurous lignite were burnt for energy

production during that era.

Some plants are capable of storing large concentrations of heavy metals in spe-

cial structures, effectively neutralising them. Such plants, such as willow—known

for its ability to store cadmium—can be used to remediate contaminated ground.

Pollution from cadmium compounds in artificial fertiliser is a widespread problem

in agricultural soils. Willows grown near water treatment plants can effectively

purify the water and be later harvested for biomass. It is, however, important to

collect the ash and dispose of it safely to avoid re-releasing it to the environment.

Arsenic is a deadly heavy metal and one of the most carcinogenic substances

known to science. It occurs naturally in certain types of rock and is responsible for

polluting many wells in India and Bangladesh. However, a potential solution has

emerged in the form of a Chinese fern that can store arsenic in its leaves. The fern

will only grow in warm and moist climates but scientists hope they can use genetic

engineering to graft its arsenic-storing properties onto other plants, especially

those with large root systems capable of purifying substantial expanses of ground.

But soil contains much more than plant roots. It is teeming with microorgan-

isms, and it is here that soil biodiversity reaches its zenith, as we will discover in

the next chapter.