Lecture 2: The Pedosphere - Soil Science

ABE 101 Principles of Soil Science and Engineering LECTURE 2 : PEDOSPHERE AND HISTORY OF SOIL SCIENCE Engr. May Rose Boston-Osoteo Instructor  PEDOSPHERE oThe pedosphere is the soil cover (blanket) of the Earth, which con...

ABE 101 Principles of Soil Science and Engineering LECTURE 2 : PEDOSPHERE AND HISTORY OF SOIL SCIENCE Engr. May Rose Boston-Osoteo Instructor  PEDOSPHERE oThe pedosphere is the soil cover (blanket) of the Earth, which consists of specific natural bodies (elements), i.e. of soils, which are diverse in their compositions and properties. oThe soil cover was formed on the surface of the land as a result of centuries-old effects (actions) of solar radiation, atmospheric moisture, vegetation, animals (animal kingdom), and microorganisms on surface layers of rocks. 2  PEDOSPHERE o Among numerous properties and functions of soils and the pedosphere as the whole, the following ones, having especially important ecological significance: ▪ unique habitat for a great diversity of life forms; ▪ link between geological and biological substance circulation in terrestrial ecosystems and the biosphere; and ▪ soil fertility in agriculture and biological productivity in natural landscapes. 3  PEDOSPHERE o Pedosphere (from Greek words pedon – soil, and sphaira – ball) is the soil shell (cover) of the Earth, similar to other terrestrial envelopes, i.e., geospheres those are the lithosphere, the hydrosphere, and the atmosphere. oThe term pedosphere is synonymous with the notion “the soil cover of the Earth”. 4  HISTORY OF SOIL SCIENCE o Some level of soils knowledge would have been necessary when the earliest known agricultural practices were used around 11,000 BP. o Civilizations all around the world showed fairly advanced soil knowledge by the 4th century AD, including irrigation, the use of terraces to control erosion, various ways of improving soil fertility, and ways to create productive artificial soils. o In many ways, the Greeks and Romans excelled in early soils knowledge. o However, these early civilizations did not take soils knowledge to the level of a true science. 5  HISTORY OF SOIL SCIENCE o Early soils knowledge was based on observations of nature; experiments to test theories were not conducted. o Through the Middle Ages, Renaissance Period, and Age of Enlightenment many advances were made and famous scientific names such as Francis Bacon, Robert Boyle, and Leonardo da Vinci worked on soils issues. In many ways, the Greeks and Romans excelled in early soils knowledge. o However, soil science did not become a true science in its own right until the 19th century with the development of genetic soil science, lead by Vasilii V. Dokuchaev. 6  HISTORY OF SOIL SCIENCE o In the 20th century, soil science moved beyond its agricultural roots. o Soils information is now used in residential development and the planning of highways, campgrounds, building foundations, septic systems, wildlife management, and many other applications. o In short, soils have become an important component across the board in land use evaluations. 7  HISTORY OF SOIL SCIENCE oHowever, soil science today is at something of a crossroads. oWhether it continues to stand alone as a separate, distinct scientific field or is absorbed into related fields such as crop science, geology, and geography is one of the biggest questions facing soil science in the 21st century. 8  HISTORY OF SOIL SCIENCE oSoil Science is the branch of science that studies soil formation, its mapping and classification, properties including physical, chemical and biological and management of soil for various purposes. 9  BRANCHES OF SOIL SCIENCE oDue to this importance of soil, scientists divide soil science into various branches for easy understanding of various soil phenomenon. There are 8 branches of soil science. These include; ▪Soil Physics - Soil Fertility ▪Soil Chemistry - Soil Survey ▪Soil Biology - Soil Technology ▪Soil Mineralogy ▪Soil Genesis and Classification (Pedology) 10  BRANCHES OF SOIL SCIENCE Soil Physics oSoil has a mechanical behavior. oBy mechanical behavior, it means the soil has physical properties through which it controls physical process in and through the soil. oThere is a need to measure that control of soil over various physical processes and for this, soil physics is the branch of soil science that focuses on this phenomenon. 11  BRANCHES OF SOIL SCIENCE Soil Chemistry oThis branch of soil science deals with the study of chemical properties and composition of soil. oIt also studies the chemical processes that takes place in soil. 12  BRANCHES OF SOIL SCIENCE Soil Biology oThis branch deals with the soil ecology. In this, scientists study the role of living organisms in biological transformations that take place in soil. Soil Mineralogy oThe study of minerals present in the soil is focused on soil mineralogy. oIt also includes the study of contributions made by those minerals in soil physical, chemical, biological and fertility 13 and their relation to the genesis of soil.  BRANCHES OF SOIL SCIENCE Soil Fertility oThe status of nutrients present in the soil and the ability of soil to provide these nutrients to the crops or plants for optimum growth under finest environmental conditions like temperature, light etc. Soil Genesis and Classification (Pedology) oThe study of weathering of rocks and minerals and soil formation is studied under this branch of soil science. oIt also includes the classification of soil in recognized 14 manner.  BRANCHES OF SOIL SCIENCE Soil Survey oSystematic analysis and examination of soil in the laboratories as well as in fields is studied in soil survey. oIt also includes the study of adaptability of soils to various crops in different areas and also interpretation of soil according to soil productivity under different management systems. 15  BRANCHES OF SOIL SCIENCE Soil Technology oIt is an applied side of the soil science. It deals with the study of principles and the practices of soil erosion and conservation. o It also deals with the soil health or soil problems that include salinity, sodic (alkaline), acidic, degradation, water logging etc. 16 END OF PRESENTATION 17