l), our knowledge of the turn-over of forest soil humus is very incomplete. This is particularly true of the organic matter in soil horizons below the humus layer.

There are three main British soils; podzol, brown earth and gley. Podzols are easily recognisable by their distinct layers or horizons. A grey or light-coloured 'E' horizon is the result of severe ...

Soil organisms, like earthworms, mix the materials together, merging the boundaries between the horizons. These soils are leached, but not heavily, so the aluminium and iron oxides are dispersed ...