Consortium for Educational Communication
Frequently asked questions (FAQs)
Q.1. What is a soil profile?
Ans: the soil forming factors result in the formation of layers within
the sol from the surface down to varying depths. These layers are
called horizons. The combination of these layers in a sequence from
the surface down is called a soil profile.
Q.2. What is a soil horizon?
Ans: A soil horizon is a layer parallel to the soil surface, whose
physical characters differ from the layers above and beneath.
Horizons are defined in most cases by obvious physical features,
chiefly colour, and texture.
Q.3. What is a genetic horizon? How it differs from a diagnostic
horizon?
Ans: Genetic horizon is a soil horizon with properties which identify
it as having been exposed to a particular process of a group of soil
forming factors and the diagnostic soil horizon is a named horizon
that has a set of quantitatively defined properties which are used
for identifying soil units within classification system. Diagnostic
horizons are distinct from genetic horizons in that their thickness
and degree of development is stipulated.
Q.4. What is a pedon?
Ans: A pedon is a soil volume represented by a soil profile with its
constituent horizons and layers.
Q.5. What is an O soil horizon?
Ans: It is an organic horizon composed of mostly vegetation that
has fallen to the ground and the remains of animals such as insects
and other microorganisms. Such horizons are predominant in forest
soils.
Q.6. Discuss the two subdivision of O horizon.
Ans: The organic horizon O is subdivided into O1 and O2, the farmer
designates an organic horizon in which essentially the original form
of most vegetative matter is visible to the naked eye and the latter
designates the horizon in which the original form of most plants
and animal matter cannot be recognized with the naked eye.
Q.7. What is an A horizon?
Ans: A horizon is a surface horizon located at the surface or below
Consortium for Educational Communication
O horizon and is composed of more or less intimate mixture of
minerals and organic matter where most the biological activity
occurs.
Q.8. What are the subdivisions of ‘A’ horizon?
Ans: The A horizon has following subdivisions:
A1 in which the feature emphasized is an accumulation of humified
organic matter immediately associated with the mineral fraction;
A2 in which the feature emphasized is the loss of clay, iron or
aluminum with resultant concentrations of Quartz or other resistant
minerals in sand and silt size and A3 which represents a transitional
zone between A and B with dominant characters of A1 or A2
Q.9. How are E horizons formed?
Ans: These are the eluviated mineral horizons formed by the loss
of silicate clay, iron, aluminum, or some combination of these,
leaving a concentration of sand and silt particles.
Q.10. Where is B horizon found? What is it composed of?
Ans: The B horizon is the illuviated subsurface horizon underlying
O, A and E horizons and is commonly referred to as subsoil. It
contains manly silicate clay or minerals such as oxides of iron and
aluminum, with gypsum and silica and leached out organic matter
hence called zone of accumulation
Q.11. What are transition horizons?
Ans: Horizons dominated by properties of one master horizon but
having subordinate properties of another are called as transition
horizons. These are represented by two capital-letters, e.g., AB, EB,
BE, or BC. The first of these symbols indicates that the properties
of the horizon so designated dominate the transitional horizon.
Q.12. Discuss in brief C soil horizon.
Ans: C horizon constitutes the transition layer between the actual
soil and parent bedrock. It is less weathered than the upper horizons
and contains partially weathered parent material of the bedrock or
sometimes the materials transported by glaciers, wind or water.
Q.13. What is an R horizon?
Ans: R horizon is also called D horizon in some soil classifications;
constitutes underlying cemented and consolidated bedrock or
sometimes the sediment from which overlying horizons have
Consortium for Educational Communication
developed.
Q.14. Discuss W horizon.
Ans: It represents water layers within or beneath the soil. It
includes permanently frozen water layers as well as unfroze
waters; however, shallow waters ice and snow above the soil are
not included in this layer.
Q.15. Define Jarosite?
Ans: Jarosite is an alteration product of pyrite resulted due to
oxidizing conditions and generally has chroma of more than 6.