Soil is composed mainly of mineral particles, organic matter, organisms, air pores, and water all of which relate to one another and with plants and microbes to form an ecosystem. The soil, as the upper layer of the earth’s surface, supports the entire human race for food, fiber, water, building materials construction sites, and waste disposal.
Soil science deals with the systematic study of soils as a non-renewable (or very slowly renewable) resource that should be judiciously managed so that it could serve our generation and future generations.
Definition of Soil
The Soil is the upper layer of the earth’s surface. The soil is highly variable from one location to another on the earth. That is, the soil comprises individual soils which are natural bodies of different characteristics and behaviors. It is a dynamic natural body composed of mineral and organic materials and living organisms in which plants grow.
A soil or an individual soil has three dimensions (Length, Width, and Height) just like a body of water. A soil occupies a small three–dimensional part of the land surface. The water or soil can be sampled and analyzed in the laboratory.
Each soil has specific properties, qualities, and characteristics. It is usually recognized in the field and indicated on a soil map.
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Such a soil map contains several soils with different names and classes according to the system of taxonomy and classification adopted by the particular country.
Soils are usually examined by describing soil pits or soil profiles using uniform definitions, terminology, and nomenclature. During the early development of soil science, the concept of soil differs among investigators with different disciplines or backgrounds.
Chemists considered soils as the storehouse of chemical compounds. Geologists on their part hold a restricted rock weathering concept.
They consider soils as disintegrated and more or less decomposed rock material mixed perhaps with organic matter from plant decay.
Engineers define soils as any unconsolidated material regardless of depth or mode of formation. To a highway engineer, the soil is regarded as a material on which a roadbed is to be placed.
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However, the most used concept of soil is the agronomic view. Soil is defined as the natural medium for the growth of land plants whether or not it has identifiable soil horizons. This old meaning is still common. Thus this book will adopt this consensual concept as our framework.
Although there are many uses of the soil, the people of the world are more concerned with food because it supports plants that supply food, fibers, drugs, and other wants of man.
Soil covers the land as a continuum, except on large rocks, in areas of perpetual frost, or on the bare ice of glaciers. In this sense, the soil has a thickness that is determined by the depth of plant roots.
What is Soil Science?
Soil science deals with the systematic study of soils as a natural resource on the surface of the earth including soil formation, classification, and mapping. Additionally, it includes the physical, chemical, biological, and fertility properties of soils as well as the properties of their management for crop production.
Knowledge of soils in the tropics and sub-tropics is increasing but far behind the soils of temperate regions. Tropical soil science emphasizes the demand for specialist knowledge and experience with tropical soils which are quite different in properties, qualities, characteristics, and management from soils of temperate regions.
Two major forces have stimulated the rise and development of soil science as a discipline. The first driving force is the use and relevance of soil to human societies. Soils are very crucial to life and therefore their study cannot be ignored. The second force is the quest after abstract knowledge to discover the laws of nature.
Soil science deals with the examination, description, and mapping of the different soils which occur in a country or district. Soil survey is fundamental to land evaluation or land use planning. It is very practical.
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Land resources, surveys, or soil surveys supply the information needed for the identification of areas for development based on the quantity of the land. Soil Scientists usually investigate the biological, chemical, physical, and mineralogical properties of soils which are then grounded and classified.
The increased knowledge of soils had led to changes in approaches to the study of soils with emphasis on quality and capacity to support plant ecosystem, animal life, and human society.
Knowledge of soils has been applied in solving practical problems, especially in crop production and land use planning.
As each soil possesses specific biological, chemical, physical, and mineralogical properties, soil scientists also specialize in dealing with particular branches of soil science such as penology (soil genesis and classification), soil physics, soil chemistry, soil biology, soil fertility, and plant nutrition, soil survey, soil technology, and soil mineralogy.
A team of soil scientists works together in soil Research Institutes and University Departments bearing in mind that real soils are in the field and that soils are an indispensable medium to grow food for people and animals and to support natural vegetation.
In summary, the need for the study of soil science by the forester, farmers, engineers, ecologists, and natural resource managers is very essential to our everyday life.
