(a) What is soil profile?
(b) Draw a well-labelled diagram of the soil profile.
(c) Describe the characteristics of the three zones of soil profile.
Explanation
(a) Solution Definition
(1) Soil profile is the vertical section of the soil from the surface down to the bedrock or parent rock below
(2) Soil profile is a vertical section through the soil showing various horizons of the soil
(b) Labelled diagram
(1) Title
(2) Zones
(3) Labelling
(c)(i) A- Horizon
(1) It is the topsoil
(2) Contains remains of plants and animals undergoing decomposition to form humus
(3) It is also known as the eluviation zone
(4) A zone of maximum biological activities of plants and soil micro-organism
(5) Darker in colour than other zones
(6) Most plant roots are anchored there.
(ii) B — Horizon
(1) It is called the subsoil
(2) It is a zone of accumulation of soil nutrients due to leaching from A -horizon
(3) It is also called the zone of illuviation
(4) Humus and other organic matters washed down from A — horizon are converted to the inorganic compound
(5) Rich in iron, aluminium and magnesium
(iii) C — Horizon
(1) It is called the parent material horizon
(2) Contains unweathered rocks
(3) Contains materials from which A and B horizons are formed
(4) Underlain by hard unweathered rocks