| Soil
formation
By
Marjorie Henry, Contributor
 |
| Friends of
Cuba Ceremony for Jamaican Students to study in Cuba, held at the Jamaica Conference
Centre, Duke and Port Royal streets, on Wednesday, September 20. Here Camille
Dixon (right), secretary of the Jamaica Cuba Students Association, speaks to the
students who are going to Cuba. - Winston Sill/ Freelance Photographer |
In the
last lesson, it was stated that ecosystems are influenced by climate, soil and
human activity. As I continue to share the information on ecosystems, I would
like to focus on soil in today's lesson. One of the definitions offered for soil
is that it is 'the unconsolidated mineral material on the immediate surface of
the earth that serves as a natural medium for the growth of land plants.' Since
the ecosystem is a community of plants and animals, you can understand that soil
plays an important role in the ecosystem. Background
knowledge of the factors that affect soil formation is vital to the study of soils.
I will encourage you to do some reading on this. In the meantime, I will list
them and then highlight a couple of them. Factors affecting soil formation are:
- Parent
Material
- Climate
- Topography
- Vegetation
and other organisms
- Time
You
would have noticed, I hope, that climate was mentioned earlier as one of the factors
influencing the ecosystem and now as a factor affecting soil formation. Climate
is regarded as the most important factor affecting soil formation. It affects
soil type both directly through its weathering effects, and indirectly as a result
of its influence upon plant life. Let me also highlight vegetation and other organisms
in soil formation. Both
plants and animals influence soil development. Vegetation establishes itself on
the parent material. Many roots will penetrate and shatter the rocks to form soils
at a later stage. Plant and animal remains produce humus or organic matter, which
helps to break down minerals found in the soil. Generally, organic matter influences
soil profile differentia, by its distribution in the soil. It also influences
soil productivity. Both of these factors for soil formation that have been highlighted
underscore the fact that there is a link or interaction within the components
of the ecosystem. Another
aspect of soil that you need to be aware of is its composition. The basic components
are Mineral
fraction - This is formed by the disintegration (weathering) of rocks and
makes up the greater portion of the soil. Water
- This has percolated into the ground as a result of precipitation and is
taken up by the plant roots. Air
- The air spaces between the soil particles allow the plant roots to breathe.
Living
organisms - Such as earthworms, help to maintain the soil structure and nutrient
balance. Organic
fraction - This comes from the dead plants and animals and is called humus.
Humus is very important to the soil. Some of the benefits of humus are that it
forms a source of food for plants; helps to maintain bacterial life in the soil;
it helps to break down pesticides in the soil and it improves the soil's ability
to retain moisture. Please
note that the components of the soil will vary according to the different types
of soil. The
syllabus advises us to have knowledge of the characteristics of the soils found
in the equatorial, tropical marine and tropical continental regions. In essence,
there are two major types found in these regions, namely latosols and rendzinas.
I will share information on these in the next lesson. The
responses to the questions given in the last lesson are as follows: 1.
The INPUTS in the ecosystem are rainwater, sunshine and minerals. 2.
Green plants are PRODUCERS within the ecosystem. 3.
The animals that feed directly off the plants are called PRIMARY CONSUMERS. 4.
Lizards, spiders and birds of prey are called SECONDARY CONSUMERS. 5.
DECOMPOSERS feed off dead organic matter. 6.
CLIMATE, SOIL and HUMAN ACTIVITY influence ecosystems.
Here
are a few questions to review today's lesson:
1.
List the factors that influence the formation of soil. 2.
How does climate affect soil formation? 3.
List the components of soil. 4.
Of what importance is HUMUS in the soil? The
following textbooks provided the references for today's lesson: Principles
of Geography by Norrel A. London and Mike Senior
The
Caribbean Environment for CXC Geography by Mark Wilson (New Edition)
Modern
Caribbean Geography by John Niles. | 
