Soil science

Study of soil as a natural resource on the surface of the earth

File:Soil sci.jpg

Soil scientist examining horizons within a soil profile

Soil science is the study of soil as a natural resource on the surface of the Earth including 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.[1]

Sometimes terms which refer to branches of soil science, such as pedology (formation, chemistry, morphology, and classification of soil) and edaphology (how soils interact with living things, 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, physical geographers, ecologists, biologists, microbiologists, silviculturists, sanitarians, archaeologists, and specialists in regional planning, all contribute to further knowledge of soils and the advancement of the soil sciences.[1]

Soil scientists have raised concerns about how to preserve soil and arable land in a world with a growing population, possible future water crisis, increasing per capita food consumption, and land degradation.[2]

## Contents

* 1 Fields of study
* 2 Research
* 3 Mapping
* 4 Classification
* 5 History
* 6 Areas of practice
* 6.1 Fields of application in soil science
* 6.2 Related disciplines
* 7 Depression storage capacity
* 8 See also
* 9 References

## Fields of study[edit | edit source]

Soil occupies the pedosphere, one of Earth's spheres that the geosciences use 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, atmosphere and hydrosphere that 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 interdisciplinary nature of soil concepts.

## Research[edit | edit source]

Dependence on and curiosity about soil, exploring the diversity and dynamics 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,[3][4] greenhouse gases, and carbon sequestration.[3] 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.

## Mapping[edit | edit source]

This section is an excerpt from Soil survey.[edit]

Soil survey, soil mapping, is the process of classifying soil types and other soil properties in a given area and geo-encoding such information. It applies the principles of soil science, and draws heavily from geomorphology, theories of soil formation, physical geography, and analysis of vegetation and land use patterns. Primary data for the soil survey are acquired by field sampling and by remote sensing. Remote sensing principally uses aerial photography, but LiDAR and other digital techniques are steadily gaining in popularity. In the past, a soil scientist would take hard-copies of aerial photography, topo-sheets, and mapping keys into the field with them. Today, a growing number of soil scientists bring a ruggedized tablet computer and GPS into the field with them. The tablet may be loaded with digital aerial photos, LiDAR, topography, soil geodatabases, mapping keys, and more.

The term soil survey may also be used as a noun to describe the published results. In the United States, these surveys were once published in book form for individual counties by the National Cooperative Soil Survey. Today, soil surveys are no longer published in book form; they are published to the web and accessed on NRCS Web Soil Survey where a person can create a custom soil survey. This allows for rapid flow of the latest soil information to the user. In the past it could take years to publish a paper soil survey. Today it takes only moments for changes to go live to the public. Also, the most current soil survey data is made available on the Download Soils Data tab at NRCS Web Soil Survey for high end GIS users such as professional consulting companies and universities.

The information in a soil survey can be used by farmers and ranchers to help determine whether a particular soil type is suited for crops or livestock and what type of soil management might be required. An architect or engineer might use the engineering properties of a soil to determine whether it is suitable for a certain type of construction. A homeowner may even use the information for maintaining or constructing their garden, yard, or home.

Soil survey information can be used to predict or estimate the potentials and limitations of soils for many specific uses. A soil survey includes an important part of the information that is used to make workable plans for land management. The information must be interpreted to be usable by professional planners and others. Predictions based on soil surveys serve as a basis for judgment about land use and management for areas ranging from small tracts to regions of several million acres. These predictions, however, must be evaluated along with economic, social, and environmental considerations before they can be used to make valid recommendations for land use and management.[5]

## Classification[edit | edit source]

Main article: soil classification

File:Global soils map USDA.jpg

Map of global soil regions from the USDA

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 morphology as an expression pedogenesis. A major difference with USDA soil taxonomy is 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.[6] 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.

## History[edit | edit source]

The earliest known soil classification system comes from China, appearing in the book Yu Gong (5th century BCE), where the soil was divided into three categories and nine classes, depending on its color, texture and hydrology.[7]

Contemporaries Friedrich Albert Fallou, the German founder of modern soil science, and Vasily Dokuchaev, the Russian founder of modern soil science, are both credited with being among the first to identify soil as a resource whose distinctness and complexity deserved to be separated conceptually from geology and crop production and treated as a whole. As a founding father of soil science Fallou has primacy in time. Fallou was working on the origins of soil before Dokuchaev was born, however Dokuchaev's work was more extensive and is considered to be the more significant to modern soil theory than Fallou's.

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.[8]

A 1914 encyclopedic definition: "the different forms of earth on the surface of the rocks, formed by the breaking down or weathering of rocks".[9] 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.[10] 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".[11]

## Areas of practice[edit | edit source]

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 2004[update] is 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 agriculture in relation to soil quality, however, has not been without its share of controversy and criticism, including critiques by Nobel Laureate Norman Borlaug and 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 soil 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
* Septic system
* Manure
* Municipal biosolids
* Food and fiber processing waste
* Identification and protection of environmentally critical areas
* Sensitive and unstable soils
* Wetlands
* Unique soil situations that support valuable habitat, and ecosystem diversity
* Management for optimum land productivity
* Silviculture
* Agronomy
* Nutrient management
* Water management
* Native vegetation
* Grazing
* Management for optimum water quality
* Stormwater management
* Sediment and erosion control
* Remediation and restoration of damaged lands
* Mine reclamation
* Flood and storm damage
* Contamination
* Sustainability of desired uses
* Soil conservation

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
* Geological phenomena
* Landslides
* Active faults
* Altering soils to achieve new uses
* Vitrification to contain radioactive wastes
* Enhancing soil microbial capabilities in degrading contaminants (bioremediation).
* Carbon sequestration
* Environmental soil science
* Pedology
* Soil genesis
* Pedometrics
* Soil morphology
* Soil micromorphology
* Soil classification
* USDA soil taxonomy
* World Reference Base[12]
* Soil biology
* Soil microbiology
* Soil chemistry
* Soil biochemistry
* Soil mineralogy
* Soil physics
* Pedotransfer function
* Soil mechanics and engineering
* Soil hydrology, hydropedology

### Fields of application in soil science[edit | edit source]

* Climate change[3]
* Ecosystem studies
* Pedotransfer function
* Soil fertility / Nutrient management
* Soil management
* Soil survey
* Standard methods of analysis
* Watershed and wetland studies

### Related disciplines[edit | edit source]

* Agricultural sciences
* Agricultural soil science
* Agrophysics science
* Irrigation management
* Anthropology
* archaeological stratigraphy
* Environmental science
* Landscape ecology
* Physical geography
* Geomorphology
* Geology
* Biogeochemistry
* Geomicrobiology
* Hydrology
* Hydrogeology
* Waste management
* Wetland science

## Depression storage capacity[edit | edit source]

Depression storage capacity, in soil science, is the ability of a particular area of land to retain water in its pits and depressions, thus preventing it from flowing.[13] Depression storage capacity, along with infiltration capacity, is one of the main factors involved in Horton overland flow, whereby water volume surpasses both infiltration and depression storage capacity and begins to flow horizontally across land, possibly leading to flooding and soil erosion. The study of land's depression storage capacity is important in the fields of geology, ecology, and especially hydrology.

## See also[edit | edit source]

* Agricultural soil science
* Agroecology
* Agrology
* Agrophysics
* Australian Society of Soil Science Incorporated (ASSSI)
* Compost
* History of soil science
* International Soil Reference and Information Centre (ISRIC)
* International Union of Soil Sciences (IUSS)
* Liming (soil)
* List of Russian Earth scientists
* List of State Soil Science Associations
* List of State Soil Science Licensing Boards
* National Society of Consulting Soil Scientists (NSCSS)
* Resonant column test
* Soil biology
* Soil Science Society of America (SSSA)
* Soil value
* World Congress of Soil Science (WCSS)

## References[edit | edit source]

1. ^ a b Jackson, J. A. (1997). Glossary of Geology (4. ed.). Alexandria, Virginia: American Geological Institute. p 604. ISBN 0-922152-34-9
2. ^ H. H. Janzen; et al. (2011). "Global Prospects Rooted in Soil Science". Soil Science Society of America Journal. 75 (1): 1. Bibcode:2011SSASJ..75....1J. doi:10.2136/sssaj2009.0216.
3. ^ a b c Ochoa-Hueso, R; Delgado-Baquerizo, M; King, PTA; Benham, M; Arca, V; Power, SA (February 2019). "Ecosystem type and resource quality are more important than global change drivers in regulating early stages of litter decomposition". Soil Biology and Biochemistry. 129: 144–152. doi:10.1016/j.soilbio.2018.11.009. S2CID 92606851.
4. ^ Pielke, Roger (12 December 2005). "Is Soil an Important Component of the Climate System?". The Climate Science Weblog. Archived from the original on 8 September 2006. Retrieved 19 April 2012.
5. ^ "Soil Survey". NRCS Nebraska. US Department of Agriculture. Retrieved 5 September 2019. This article incorporates text from this source, which is in the public domain.
6. ^ "Vernacular Systems". Archived from the original on 6 March 2007. Retrieved 19 April 2012.
7. ^ Arnold, R. et al. (2009) A Handbook of Soil Terminology, Correlation and Classification Earthscan, London, England.
8. ^ Krasilnikov, N.A. (1958) Soil Microorganisms and Higher Plants Archived 12 November 2004 at the Wayback Machine
9. ^ Wikisource:The New Student's Reference Work/4-0310
10. ^ Buol, S. W.; Hole, F. D. & McCracken, R. J. (1973). Soil Genesis and Classification (First ed.). Ames, IA: Iowa State University Press. ISBN 978-0-8138-1460-5..
11. ^ C. C. Nikiforoff (1959). "Reappraisal of the soil: Pedogenesis consists of transactions in matter and energy between the soil and its surroundings". Science. 129 (3343): 186–196. Bibcode:1959Sci...129..186N. doi:10.1126/science.129.3343.186. PMID 17808687.
12. ^ "World Reference Base | FAO Soils Portal | Food and Agriculture Organization of the United Nations".
13. ^ Hansen, Bjarne, Per Schjønning, and Erik Sibbesen. "Roughness indices for estimation of depression storage capacity of tilled soil surfaces Archived 25 August 2017 at the Wayback Machine." Soil and Tillage Research 52.1 (1999): 103-111.

* Soil Survey Staff (1993). Soil Survey: Early Concepts of Soil. (html) Soil Survey Manual USDA Handbook 18, Soil Conservation Service. U.S. Department of Agriculture. URL accessed on 2004-11-30.
* Marion LeRoy Jackson (2005). Soil Chemical Analysis: Advanced Course. UW-Madison Libraries Parallel Press. pp. 5–. ISBN 978-1-893311-47-3.

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Soil science

* History
* Index

Main fields|

* Pedology
* Edaphology
* Soil biology
* Soil microbiology
* Soil zoology
* Soil ecology
* Soil physics
* Soil mechanics
* Soil chemistry
* Environmental soil science
* Agricultural soil science

File:Soil profile.svg

Soil topics|

* Soil
* Pedosphere
* Soil morphology
* Pedodiversity
* Soil formation
* Soil erosion
* Soil contamination
* Soil retrogression and degradation
* Soil compaction
* Soil compaction (agriculture)
* Soil sealing
* Soil salinity
* Alkali soil
* Soil pH
* Soil acidification
* Soil health
* Soil life
* Soil biodiversity
* Soil quality
* Soil value
* Soil fertility
* Soil resilience
* Soil color
* Soil texture
* Soil structure
* Pore space in soil
* Pore water pressure
* Soil crust
* Soil horizon
* Soil biomantle
* Soil carbon
* Soil gas
* Soil respiration
* Soil organic matter
* Soil moisture
* Soil water (retention)

Soil type|

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Soil classification

World Reference Base
for Soil Resources (1998–)|

* Acrisols
* Alisols
* Andosols
* Anthrosols
* Arenosols
* Calcisols
* Cambisols
* Chernozem
* Cryosols
* Durisols
* Ferralsols
* Fluvisols
* Gleysols
* Gypsisols
* Histosol
* Kastanozems
* Leptosols
* Lixisols
* Luvisols
* Nitisols
* Phaeozems
* Planosols
* Plinthosols
* Podzols
* Regosols
* Retisols
* Solonchaks
* Solonetz
* Stagnosol
* Technosols
* Umbrisols
* Vertisols

USDA soil taxonomy|

* Alfisols
* Andisols
* Aridisols
* Entisols
* Gelisols
* Histosols
* Inceptisols
* Mollisols
* Oxisols
* Spodosols
* Ultisols
* Vertisols

Other systems|

* FAO soil classification (1974–98)
* Unified Soil Classification System
* AASHTO Soil Classification System
* Référentiel pédologique (French classification system)
* Canadian system of soil classification
* Australian Soil Classification
* Polish Soil Classification
* 1938 USDA soil taxonomy
* List of U.S. state soils
* List of vineyard soil types

Non-systematic soil types|

* Sand
* Silt
* Clay
* Loam
* Topsoil
* Subsoil
* Soil crust
* Claypan
* Hardpan
* Gypcrust
* Caliche
* Parent material
* Pedosphere
* Laimosphere
* Rhizosphere
* Bulk soil
* Alkali soil
* Bay mud
* Blue goo
* Brickearth
* Brown earth
* Calcareous grassland
* Dark earth
* Dry quicksand
* Duplex soil
* Eluvium
* Expansive clay
* Fill dirt
* Fuller's earth
* Hydrophobic soil
* Loess
* Lunar soil
* Martian soil
* Mud
* Muskeg
* Paleosol
* Peat
* Prime farmland
* Serpentine soil
* Spodic soil
* Stagnogley
* Subaqueous soil
* Terra preta
* Terra rossa
* Tropical peat
* Yedoma

Types of soil

Applications|

* Soil conservation
* Soil management
* Soil guideline value
* Soil survey
* Soil test
* Soil governance
* Soil value
* Soil salinity control
* Erosion control
* Soil policy (Victoria, Australia)
* Agroecology
* Liming (soil)

Related fields|

* Geology
* Geochemistry
* Petrology
* Geomorphology
* Geotechnical engineering
* Hydrology
* Hydrogeology
* Biogeography
* Earth materials
* Archaeology
* Agricultural science
* Agrology

Societies, Initiatives|

* Australian Society of Soil Science Incorporated
* Canadian Society of Soil Science
* Central Soil Salinity Research Institute (India)
* German Soil Science Society
* Indian Institute of Soil Science
* International Union of Soil Sciences
* International Year of Soil
* National Society of Consulting Soil Scientists (USA)
* OPAL Soil Centre (UK)
* Soil Science Society of Poland
* Soil and Water Conservation Society (USA)
* Soil Science Society of America
* World Congress of Soil Science

Scientific journals|

* Acta Agriculturae Scandinavica B
* Journal of Soil and Water Conservation
* Plant and Soil
* Pochvovedenie
* Soil Research
* Soil Science Society of America Journal

See also|

* Land use
* Land conversion
* Land management
* Vegetation
* Infiltration (hydrology)
* Groundwater
* Crust (geology)
* Impervious surface/Surface runoff

* Wikipedia:WikiProject Soil
* Category soil
* Category soil science
* List of soil scientists

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