Life in the Soil - Soil: Reflections on the Basis of our Existence - page 67

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Inventive microfauna. Amoebae are single-cell organisms that can number tens of thousands in
a single teaspoonful of soil. Some have a shell, like the one in the upper image; others have no
particular form but develop arm-like extensions that can capture bacteria, their principal food. In
the middle photo, an amoeba moves within a pore and elongates its body when the pore becomes
narrow. The amoeba is visible in white and the pore cavity is blue. A special group of amoebae
burrow like vampires into fungal hyphae and suck out the cell fluid. They even go by the Latin
generic name Vampyrellids
The most common multicellular land animals in the soil are nematodes, a sort of millimetre-
length worm. Together with amoebae, they accelerate nutrient turnover when consuming bacteria
and fungal hyphae. Some can cause disease: many of them in plants, others in animals. The plant
parasitic nematodes in the bottom image puncture plant cells with their stylet and ingest the content

why earthworms took leaves into the soil, suggesting that they used them to insu-
late their chambers against draughts. Presumably he based this on Britain's damp
and poorly insulated buildings.
Darwin also took an interest in how worms reacted to stimuli. One experiment
involved placing worm-containing pots in his living room while his wife Emma
played Chopin on the piano. The worms did not react to the music, but when
Darwin placed the pots on the piano the vibrations caused them to tunnel into
the soil. This reminds me of the lawn in Tomelilla and how the vibrations from
African drums echoed through my body. Perhaps the worms were reacting to the
same good vibrations.
By modifying the physical structure of the soil, worms facilitate decompo-
sition of organic matter and accelerate plants' access to vital nutrients. It could
take a hundred years for the earthworms to work their way through the soil of
the Tomelilla lawn, during which they could produce up to one hundred tonnes
of excrement per hectare in the form of the “castings” one sees on the surface.
This may sound a lot but is nothing compared to what earthworms can achieve
in the most fertile soils. The Nile river valleys are rich in earthworms and scien-
tists there have estimated that they eat their way through two and a half thousand
tonnes of earth per year and per hectare. Worm castings consist of organic matter,
mineral soil and mucus from the worms' gut and the mucus-forming bacteria that
live there. Darwin explained how mineral particles ground down the organic mat-
ter like a miller's stone. Worms live on the nutrients released by bacteria in their
gut—a moist environment in which the bacteria thrive when breaking down cel-
lulose and other compounds.
Earthworms' tunnels create pores that aerate the soil, allowing rainwater to pen-
etrate the ground rather than collect on the surface, where it can damage the soil
structure. Plant roots are known to be able to penetrate earth packed thickly by
heavy farm machinery by utilising tunnels made by worms. I am always mindful
of keeping my vegetable patch well aerated to create optimal growing conditions,
digging nutrient-rich compost earth full of earthworms a good twenty centimetres
down. Woe betide anyone who treads on the flowerbeds and compacts the soil: even
with a spade or pitchfork you cannot recreate the earthworms' delicate tunnels.
In natural ecosystems, earthworms favour nutrient-rich soil in deciduous forest
with a neutral pH. Here they carry fallen leaves with them below ground, where