Site A is a field in the countryside outside Geneva, bordered by a hedge and used in rotation for grazing cattle and growing crops. Its soil formed on moraine left by the Rhône glacier: sand, silt, clay and stones of every size, weathered from rock the ice dumped here. The upper layer is dark with humus, the pore spaces hold water and air, and the soil is full of earthworms, fungi and bacteria.

Each autumn leaves fall from the hedge onto the edge of the field, and the farmer spreads cattle manure. Rain soaks into the surface and drains down through the soil. Earthworms drag dead leaves into their burrows, where fungi and bacteria break them down into humus and release carbon dioxide. Over the summer the crop photosynthesises, loses water vapour from its leaves, and takes up water and nitrate through its roots. Some nitrate is carried down below the roots by draining water and reaches the gravel aquifer beneath the field, the nappe du Genevois. On hot days water evaporates from the soil surface, and in a summer storm soil is washed off any ground left bare. In winter the cattle graze the grass.

Source: Site A as described in the ESS lessons land.1.1 and land.1.2, with the sources cited there (Republic and Canton of Geneva; Federal Office for the Environment)