Various definitions of soil have emerged depending upon the point of view of soil users. Perhaps the first and the most popular definition is that given by agriculturists that soil is a medium or a stuff in which plants grow.
The soil chemist sees the soil either as a chemical laboratory where various chemical processes and reactions take place or as a test tube into which plant nutrient can be introduced for the benefit of plant.
Both the soil physicist and geologist conceive soil as a collection of matter, solid, liquid and recognizable mechanical properties associated with the rock from which they are formed.
The engineers see the soil either as a material for civil engineering constructions or in terms of its suitability for foundation laying.
To the geographer, the term “soil” means the uppermost superficial layer of loose or unconsolidated material overlying the crustal rock in which plants may grow.
The Science of Pedology
We now turn to looking at the soil, as the pre-occupation of the science of pedology. Pedology is the science of soils. It studies the origins, characteristics and uses of soils.
Let us now consider the interests of the penologist.
The pedologist is interested in the appearance of the soil.
The pedologist wants to know the mode of formation of such a soil.
The physical, chemical and biological compositions also interest the pedologist.
Besides all these, the pedologist wants to classify the soil types of the world and how they are distributed over the surface of the earth.
The pedologist is also interested in how soils are managed and conserved
Do you know that for the pedologist to achieve his/her interests in the study of soils he/she makes use of a larger number of branches of scientific knowledge? These fields are many.
They include biology, chemistry, physics, agriculture, forestry, geology, geography archaeology and history.
Functions of Soil
Soil has many functions it performs. Out of these we will consider five of them.
Soil acts as a medium in which seeds, spores and corm may germinate. This is because most seeds, spores corm need the protection; warmth and moisture of the soil to enable them commence their life cycles.
Soil provides support for many growing plants, that is, soil is essential as an anchorage for plants.
Soil is the main medium whereby water is brought to the roots of plants. This is so because soil is capable of holding moisture and air, both of which are necessary for plant life.
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It is through soil that nitrogen, potash, phosphorus, potassium, iron and other numerous mineral substances essential to plant life are supplied.
Lastly, soil functions as a habitat for organisms whose biological activities are responsible for the recycling of mineral nutrients derived from organic matter.