- Soil science
Soil science is the study of
soilas a natural resourceon the surface of the earthincluding soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils.
Sometimes terms which refer to branches of soil science, such as pedology (formation, chemistry, morphology and classification of soil) and
edaphology(influence of soil on organisms, especially plants), are used as if synonymous with soil science. The diversity of names associated with this discipline is related to the various associations concerned. Indeed, engineers, agronomists, chemists, geologists, geographers, biologists, microbiologists, sylviculturists, sanitarians, archaeologists, and specialists in regional planning, all contribute to further knowledge of soils and the advancement of the soil sciences.
Fields of study
Soil occupies the
pedosphere, one of Earth's spheresthat the geosciencesuse to organize the Earth conceptually. This is the conceptual perspective of pedology and edaphology, the two main branches of soil science. Pedology is the study of soil in its natural setting. Edaphology is the study of soil in relation to soil-dependent uses. Both branches apply a combination of soil physics, soil chemistry, and soil biology. Due to the numerous interactions between the biosphere, atmosphereand hydrospherethat are hosted within the pedosphere, more integrated, less soil-centric concepts are also valuable. Many concepts essential to understanding soil come from individuals not identifiable strictly as soil scientists. This highlights the interdisciplinarynature of soil concepts.
Dependence on and curiosity about soil, exploring the diversity and dynamic of this resource continues to yield fresh discoveries and insights. New avenues of soil research are compelled by a need to understand soil in the context of
climate change, [ Pielke, Roger( December 12, 2005) [http://climatesci.atmos.colostate.edu/2005/12/19/is-soil-an-important-component-of-the-climate-system/ Is Soil an Important Component of the Climate System?] The Climate Science Weblog. Url last accessed 2006- 04-19] greenhouse gases, [cite web |url=http://www.co2science.org/scripts/CO2ScienceB2C/subject/g/summaries/glomalin.jsp |title= Glomalin -- Summary |archiveurl=http://web.archive.org/web/20070708192258/http://www.co2science.org/scripts/CO2ScienceB2C/subject/g/summaries/glomalin.jsp |archivedate=2007-07-08 Last updated 25 January 2006. CO2 Science. Url last accessed 2006- 04-19] [cite web |url=http://www.co2science.org/scripts/CO2ScienceB2C/subject/s/summaries/soilstability.jsp |title= Soil (stability) -- Summary |archiveurl=http://web.archive.org/web/20070225230420/http://www.co2science.org/scripts/CO2ScienceB2C/subject/s/summaries/soilstability.jsp |archivedate=2007-02-25. CO2 Science. URL last accessed 2006- 04-19] and carbon sequestration. [cite web |url=http://www.co2science.org/scripts/CO2ScienceB2C/subject/c/carbonsoils.jsp |title= Soil Carbon Sequestration |archiveurl=http://web.archive.org/web/20070708192202/http://www.co2science.org/scripts/CO2ScienceB2C/subject/c/carbonsoils.jsp |archivedate=2007-07-08. CO2 Science. Url last accessed 2006- 04-19] Interest in maintaining the planet's biodiversity and in exploring past cultures has also stimulated renewed interest in achieving a more refined understanding of soil.
Most knowledge of soil in nature comes from
soil surveyefforts. Soil survey, or soil mapping, is the process of determining the soil types or other properties of the soil cover over a landscape, and mapping them for others to understand and use. It relies heavily on distinguishing the individual influences of the five classic soil forming factors. This effort draws upon geomorphology, physical geography, and analysis of vegetation and land-use patterns. Primary data for the soil survey are acquired by field sampling and supported by remote sensing.
As of 2006, the
World Reference Base for Soil Resources, via its Land & Water Development division, is the pre-eminent soil classification system. It replaces the previous FAO soil classification.
The WRB borrows from modern soil classification concepts, including
USDA soil taxonomy. The classification is based mainly on soil morphologyas an expression pedogenesis. A major difference with USDA soil taxonomyis that soil climate is not part of the system, except insofar as climate influences soil profile characteristics.
Many other classification schemes exist, including vernacular systems. The structure in vernacular systems are either nominal, giving unique names to soils or landscapes, or descriptive, naming soils by their characteristics such as red, hot, fat, or sandy. Soils are distinguished by obvious characteristics, such as physical appearance (e.g., color, texture, landscape position), performance (e.g., production capability, flooding), and accompanying vegetation. [ [http://forages.oregonstate.edu/is/ssis/main.cfm?PageID=168 Vernacular Systems] Url last accessed on
2006- 04-18] A vernacular distinction familiar to many is classifying texture as heavy or light. Light soil content and better structure, take less effort to turn and cultivate. Contrary to popular belief light soils do not weigh less than heavy soils on an air dry basis nor do they have more porosity.
Vasily Dokuchaev, a Russian geologist, geographer and early soil scientist, is credited with identifying soil as a resource whose distinctness and complexity deserved to be separated conceptually from geology and crop production and treated as a whole.
Previously, soil had been considered a product of chemical transformations of rocks, a dead substrate from which plants derive nutritious elements. Soil and bedrock were in fact equated. Dokuchaev considers the soil as a natural body having its own genesis and its own history of development, a body with complex and multiform processes taking place within it. The soil is considered as different from bedrock. The latter becomes soil under the influence of a series of soil-formation factors (climate, vegetation, country, relief and age). According to him, soil should be called the "daily" or outward horizons of rocks regardless of the type; they are changed naturally by the common effect of water, air and various kinds of living and dead organisms. [Krasilnikov, N.A. (1958) [http://www.soilandhealth.org/01aglibrary/010112Krasil/010112krasil.intro.html Soil Microorganisms and Higher Plants] ]
A 1914 encyclopedic definition: "the different forms of earth on the surface of the rocks, formed by the breaking down or weathering of rocks". [web cite |url=http://en.wikisource.org/wiki/The_New_Student%27s_Reference_Work/4-0310 |title=Soils |work=The New Student's Reference Work |date= 1914 |publisher= F. E. Compton and Company |accessdate=2008-07-08] serves to illustrate the historic view of soil which persisted from the 19th century. Dokuchaev's late 19th century soil concept developed in the 20th century to one of soil as earthy material that has been altered by living processes.cite book | last = Buol | first = S. W. | authorlink = | coauthors = Hole, F. D. and McCracken, R. J. | title = Soil Genesis and Classification | edition = First | date = 1973 | publisher = Iowa State University Press | location = Ames, IA | id = ISBN 978-0-8138-1460-5 .] A corollary concept is that soil without a living component is simply a part of earth's outer layer.
Further refinement of the soil concept is occurring in view of an appreciation of energy transport and transformation within soil. The term is popularly applied to the material on the surface of the earth's moon and Mars, a usage acceptable within a portion of the scientific community. Accurate to this modern understanding of soil is Nikiforoff's 1959 definition of soil as the "excited skin of the sub aerial part of the earth's crust". [cite journal | author = C. C. Nikiforoff | title = Reappraisal of the soil: Pedogenesis consists of transactions in matter and energy between the soil and its surroundings | journal = Science | volume = 129 | pages = 186–196 | doi = 10.1126/science.129.3343.186 | year = 1959 | pmid = 17808687]
Areas of practice
Academically, soil scientists tend to be drawn to one of five areas of specialization: microbiology, pedology, edaphology, physics or chemistry. Yet the work specifics are very much dictated by the challenges facing our civilization's desire to sustain the land that supports it, and the distinctions between the sub-disciplines of soil science often blur in the process. Soil science professionals commonly stay current in soil chemistry, soil physics, soil microbiology, pedology, and applied soil science in related disciplines
One interesting effort drawing in soil scientists in the USA
as of 2004is the Soil Quality Initiative. Central to the Soil Quality Initiative is developing indices of soil health and then monitoring them in a way that gives us long term (decade-to-decade) feedback on our performance as stewards of the planet. The effort includes understanding the functions of soil microbiotic crusts and exploring the potential to sequester atmospheric carbon in soil organic matter. The concept of soil quality, however, has not been without its share of controversy and criticism, including critiques by Nobel Laureate Norman Borlaugand World Food Prize Winner Pedro Sanchez.
A more traditional role for soil scientists has been to map soils. Most every area in the United States now has a published soil survey, which includes interpretive tables as to how soil properties support or limit activities and uses. An internationally accepted soil taxonomy allows uniform communication of soil characteristics and functions. National and international soil survey efforts have given the profession unique insights into landscape scale functions. The landscape functions that soil scientists are called upon to address in the field seem to fall roughly into six areas:
* Land-based treatment of wastes
**Food and fiber processing waste
* Identification and protection of environmentally critical areas
**Sensitive and unstable soils
**Unique soil situations that support valuable habitat, and
* Management for optimum land productivity
* Management for optimum water quality
* Remediation and restoration of damaged lands
**Flood and storm damage
* Sustainability of desired uses
There are also practical applications of soil science that might not be apparent from looking at a published soil survey.
* Radiometric dating: specifically a knowledge of local pedology is used to date prior activity at the site
Stratification (archeology)where soil formation processes and preservative qualities can inform the study of archaeological sites
* Altering soils to achieve new uses
Vitrificationto contain radioactive wastes
**Enhancing soil microbial capabilities in degrading contaminants (
Environmental soil science
** Soil genesis
*** Soil micromorphology
USDA soil taxonomy
* Soil biology
** Soil microbiology
** Soil biochemistry
** Soil mineralogy
Soil mechanicsand engineering
* Soil hydrology,
Fields of application in soil science
** archaeological stratigraphy
International Union of Soil Sciences(IUSS)
Soil Science Society of America(SSSA)
Australian Society of Soil Science Incorporated(ASSSI)
World Congress of Soil Science(WCSS)
List of Universities with Soil Science Curriculum
List of State Soil Science Licensing Boards
List of State Soil Science Associations
International Soil Reference and Information Centre
* [https://www.soils.org/certifications/pdf/soil_sci_cert.pdf Certified Professional Soil Scientist]
* [http://www.nscss.org/REGISTRY%20APPLICATION.pdf Registered Professional Soil Scientist] (PDF)
* [http://info.soil.ncsu.edu/ Soil-Science.info]
* [http://soilsciences.blogspot.com/ The Soil Science Daily]
* [http://www.isric.org/ ISRIC - World Soil Information]
* [http://www.soilscientist.org/ IPSS - Insitute of Professional Soil Scientists]
* [http://www.soils.org.uk/ BSSS - British Society of Soil Science]
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