Soil 37738 225441393 2008-07-13T18:37:55Z 71.107.100.54 /* Characteristics */ [[Image:Lössacker.jpg|thumb|[[Loess]] field in Germany]] [[Image:Stagnogley.JPG|thumb|Surface-water-[[Gley soil|gley]] developed in [[glacial till]], Northern Ireland]] {{otheruses}} '''Soil''' is the naturally occurring, unconsolidated or loose covering of broken rock particles and decaying organic matter on the surface of the [[Earth]], capable of supporting [[soil life|life]].<ref>Voroney, R. P., 2006. The Soil Habitat ''in'' Soil Microbiology, Ecology and Biochemistry, Eldor A. Paul ed. ISBN=0125468075</ref> <ref>[http://www.columbia.edu/itc/cerc/seeu/atlantic/restrict/modules/module10_content.html James A. Danoff-Burg, Columbia University The Terrestrial Influence: Geology and Soils]</ref> Soil particles pack loosely, forming a soil structure filled with pore spaces. These pores contain soil solution (liquid) and air (gas).<ref>Taylor, S. A., and G. L. Ashcroft. 1972. Physical Edaphology</ref> Accordingly, soils are often treated as a three [[state of matter|state]] system.<ref>McCarty, David. 1982. Essentials of Soil Mechanics and Foundations </ref> Soil is also known as earth: it is the substance from which our planet takes its name. ==Characteristics== [[Image:Soil profile.png|thumb|Darkened topsoil and reddish subsoil [[soil horizons|layers]] are typical in [[humid subtropical climate|some regions.]]]] [[Soil color]] is the first impression one has when viewing soil. Striking colors and contrasting patterns are especially memorable. The [[Red River (Mississippi watershed)|Red River]] in [[Louisiana]] carries sediment eroded from extensive reddish soils like [[Port Silt Loam]] in [[Oklahoma]]. Soil color results from chemical and biological weathering. As the primary minerals in [[parent material]] weather, the elements combine into new and colorful compounds. Iron forms secondary minerals with a yellow or red color; organic matter decomposes into brown compounds; and manganese, sulfur and nitrogen can form black mineral deposits.<ref>{{web cite | url = http://soils.usda.gov/education/resources/k_12/lessons/color/ | publisher = [[United States Department of Agriculture]] - [[Natural Resources Conservation Service]] | title = The Color of Soil | accessdate = 2008-07-08}} </ref> [[Soil structure]] is the arrangement of soil particles into aggregates. These may have various shapes, sizes and degrees of development or expression.<ref>{{web cite | author= Soil Survey Division Staff|date=1993 | url= http://soils.usda.gov/technical/manual/contents/chapter3g.html#60 | title = Soil Structure | work= Handbook 18. Soil survey manual | Publisher= Soil Conservation Service. U.S. Department of Agriculture | accessdate= 2008-07-08}}</ref> [[Soil texture]] refers to [[sand]], [[silt]] and [[clay]] composition. [[Sand]] and silt are the product of physical weathering while clay is the product of chemical weathering. Clay content is particularly influential on soil behavior due to a high retention capacity for nutrients and water.<ref>{{web cite | author = R. B. Brown |date=September 2003 | url = http://edis.ifas.ufl.edu/SS169 | title = Soil Texture | work = Fact Sheet SL-29 | publisher = University of Florida, Institute of Food and Agricultural Sciences | accessdate = 2008-07-08}}</ref> The electrical [[resistivity]] of soil can affect the rate of [[galvanic corrosion]] of metallic structures in contact with it. Higher moister content or increased [[electrolyte]] concentration can lower the resistivity and thereby increase the rate of corrosion.<ref name="ArmySoil">{{cite web |url=http://www.usace.army.mil/publications/armytm/TM5-811-7/ |title=Electrical Design, Cathodic Protection |publisher=United States Army Corps of Engineers |date=1985-04-22 |accessdate=2008-07-02 }}</ref> Soil resistivity values typically range from about 100 to 1000&nbsp;[[Ohm|&Omega;]]&middot;[[Metre|m]], but more extreme values are not unusual.<ref>{{cite web |url=http://www.smeter.net/grounds/earthres-2.php |title=Typical Soil Characteristics of Various Terrains |author=R. J. Edwards |date=1998-02-15 |accessdate=2008-07-02 }}</ref> ===Formation=== Soil formation, or [[pedogenesis]], is the combined effect of physical, chemical, biological, and anthropogenic processes on soil parent material resulting in the formation of [[soil horizon]]s. Soil is always changing. The long periods over which change occurs and the multiple influences of change mean that simple soils are rare. While soil can achieve relative stability in properties for extended periods of time, the soil life cycle ultimately ends in soil conditions that leave it vulnerable to erosion. Little of the soil continuum of the earth is older than [[Tertiary]] and most no older than [[Pleistocene]].<ref name=Buol73>{{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 0-8138-1460-X}}.</ref> Despite the inevitability of [[soils retrogression and degradation]], most soil cycles are long and productive. How the soil "life" cycle proceeds is influenced by at least five classic soil forming factors: regional climate, biotic potential, topography, parent material, and the passage of time. An example of soil development from bare rock occurs on recent [[lava]] flows in warm regions under heavy and very frequent rainfall. In such climates plants become established very quickly on [[basaltic]] lava, even though there is very little organic material. The plants are supported by the porous rock becoming filled with nutrient bearing water, for example carrying dissolved bird droppings or [[guano]]. The developing plant roots themselves gradually breaks up the porous lava and organic matter soon accumulates but, even before it does, the predominantly porous broken lava in which the plant roots grow can be considered a soil. <!--- mechanical weathering, impact pulverization, water present as ice, solar radiation, evidence of life in sulfides, potential for redox gradients relevant to secondary mineral formation. some types of soil don't desolve the water for the plants it might stay on top or if the pot has a crack it might\will throw it out and not hold it thats if you give it to much water.--> ===In nature=== Biogeography is the study of spatial variations in biological communities. Soils are a restricting factor as to what plants can grow in which environments. Soil scientists survey soils in the hope of understanding controls as to what vegetation can and will grow in a particular location Geologists also have a particular interest in the patterns of soil on the surface of the earth. Soil texture, color and chemistry often reflect the underlying geologic parent material and [[soil types]] often change at geologic unit boundaries. Buried [[paleosols]] mark [[unconformity|previous land surfaces]] and record [[paleoclimatology|climatic conditions from previous]] [[era (geology)|era]]s. Geologists use this [[paleopedological record]] to understand the ecological relationships in past ecosystems. According to the theory of [[biorhexistasy]], prolonged conditions conducive to forming deep, weathered soils result in increasing ocean salinity and the formation of limestone. Geologists use [[soil profile]] features to establish the duration of surface stability in the context of [[geologic fault]]s or [[slope stability]]. An offset [[subsoil]] horizon indicates rupture during soil formation and the degree of subsequent subsoil formation is relied upon to establish time since rupture. Soil examined in [[shovel test pit]]s is used by archaeologists for relative dating based on stratigraphy (as opposed to [[absolute dating]]). What is considered most typical is to use soil profile features to determine the maximum reasonable pit depth than needs to be examined for archaeological evidence in the interest of [[cultural resources management]]. Soils altered or formed by man (anthropic and [[anthropogenic]] soils) are also of interest to archaeologists. An example is [[Terra preta|Terra preta do Indio]]. ==Uses== {{Expand-section|examples of uses of soil as a material and uses involving soil as a natural resource|date=January 2008}} [[Image:NRCSIA99560.png|thumb|A homeowner tests soil to apply only the nutrients needed.]] [[Image:Rammed earth wall - Eden Project.jpg|thumb|Due to their thermal mass, [[rammed earth]] walls fit in with environmental sustainability aspirations.]] [[Image:NRCSIA99567.png|thumb|A homeowner sifts soil made from his [[compost]] bin in background. Composting is an excellent way to recycle household and yard wastes.]] Soil material is a critical component in the mining and construction industries. Soil serves as a foundation for most construction projects. Massive volumes of soil can be involved in surface mining, road building, and dam construction. [[Earth sheltering]] is the architectural practice of using soil for external [[thermal mass]] against building walls. Soil resources are critical to the environment, as well as to food and fiber production. Soil provides minerals and water to plants. Soil absorbs rainwater and releases it later thus preventing floods and drought. Soil cleans the water as it percolates. Soil is the habitat for many organisms. [[Waste management]] often has a soil component. [[Septic drain field]]s treat [[septic tank]] effluent uses aerobic soil processes. [[Landfill]]s use soil for [[daily cover]]. Organic soils, especially [[peat]], serve as a significant fuel resource. Both humans in many cultures and animals occasionally [[Geophagy| eat soil]]. ==Degradation== [[Land degradation]] is a human induced or natural process which impairs the capacity of [[land (economics)|land]] to function. Soils are the critical component in land degradation when it involves acidification, contamination, desertification, erosion, or salination. While [[soil acidification]] of alkaline soils is beneficial, it degrades land when soil acidity lowers crop productivity and increases soil vulnerability to contamination and erosion. Soils are often initially acid because their [[parent material]]s were acid and initially low in the [[Base (chemistry)|basic]] [[cation]]s ([[calcium]], [[magnesium]], [[potassium]], and [[sodium]]). Acidification occurs when these elements are removed from the soil profile by normal rainfall or the harvesting of crops. Soil acidification is accelerated by the use of acid-forming nitrogenous fertilizers and by the effects of [[acid precipitation]]. [[Soil contamination]] at low levels are often within soil capacity to treat and assimilate. Many waste treatment processes rely on this treatment capacity. Exceeding treatment capacity can damage soil biota and limit soil function. [[Derelict soil]]s occur where industrial contamination or other development activity damages the soil to such a degree that the land cannot be used safely or productively. [[Remediation]] of derelict soil uses principles of [[geology]], physics, chemistry, and biology to degrade, attenuate, isolate, or remove soil contaminants and to restore soil functions and values. Techniques include leaching, air sparging, chemical amendments, [[phytoremediation]], [[bioremediation]], and natural attenuation. [[Desertification]] is an environmental process of ecosystem degradation in arid and semi-arid regions, or as a result of human activity. It is a common misconception that [[drought]]s cause desertification. Droughts are common in arid and semiarid lands. Well-managed lands can recover from drought when the rains return. Soil management tools include maintaining soil nutrient and organic matter levels, reduced tillage and increased cover. These help to control erosion and maintain productivity during periods when moisture is available. Continued land abuse during droughts, however, increases land degradation. Increased population and livestock pressure on marginal lands accelerates desertification. Soil [[erosion]]al loss is caused by wind, water, ice, movement in response to [[gravitation|gravity]]. Although the processes may be simultaneous, erosion is distinguished from [[weathering]]. Erosion is an intrinsic natural process, but in many places it is increased by human [[land use]]. Poor land use practices include [[deforestation]], [[overgrazing]], and improper construction activity. Improved management can limit erosion using techniques like limiting disturbance during construction, avoiding construction during erosion prone periods, intercepting runoff, [[Terrace (agriculture)|terrace]]-building, use of erosion suppressing cover materials and planting trees or other soil binding plants. [[Image:20060422094342.jpg|right|thumb|Sediment in the Yellow River.]] A serious and long-running water erosion problem is in [[China]], on the middle reaches of the [[Yellow River]] and the upper reaches of the [[Yangtze River]]. From the Yellow River, over [[1 E12 kg|1.6 billion tons]] of sediment flow each year into the ocean. The [[sediment]] originates primarily from water erosion in the [[Loess Plateau]] region of northwest China. Soil piping is a particular form of soil erosion that occurs below the soil surface. It is associated with levee and dam failure as well as sink hole formation. Turbulent flow removes soil starting from the mouth of the seep flow and subsoil erosion advances upgradient.<ref> {{cite journal | last = Jones | first = J. A. A. | title = Soil piping and stream channel initiation | journal = Water Resources Research | volume = 7 | issue = 3 | pages = 602–610 | date = 1976 | doi = 10.1029/WR007i003p00602 }} </ref> The term sand boil is used to describe the appearance of the discharging end of an active soil pipe.<ref>{{cite web |last=Dooley |first=Alan |title=Sandboils 101: Corps has experience dealing with common flood danger | Work = Engineer Update |publisher=US Army Corps of Engineers |date=June, 2006 |url=http://www.hq.usace.army.mil/cepa/pubs/jun06/story8.htm |accessdate = 2008-05-14 }}</ref> [[Soil salination]] is the accumulation of free [[salt]]s to such an extent that it leads to degradation of soils and vegetation. Consequences include corrosion damage, reduced plant growth, erosion due to loss of plant cover and soil structure, and water quality problems due to sedimentation. Salination occurs due to a combination of natural and human caused processes. Aridic conditions favor salt accumulation. This is especially apparent when soil parent material is saline. Irrigation of arid lands is especially problematic. All irrigation water has some level of salinity. Irrigation, especially when it involves leakage from canals, often raise the underlying water table. Rapid salination occurs when the land surface is within the capillary fringe of saline groundwater. [[Salinity control]] involves flushing with higher levels of applied water in combination with tile drainage.<ref>{{cite book | title = Drainage Manual: A Guide to Integrating Plant, Soil, and Water Relationships for Drainage of Irrigated Lands | year = 1993 | publisher = Interior Dept., Bureau of Reclamation | id = ISBN 0-16-061623-9}} </ref>. ==See also== {{wikiquote}} {{commonscat|Soil}} *[[Geohumus]] *[[Geoponic]] *[[Humus]] *[[Manure]] *[[Mud]] *[[Red Mediterranean soil]] *[[Soil contamination]] *[[Soil erosion]] *[[Soil functions]] *[[Soil mechanics]] *[[Shrink-swell capacity]] == References == {{reflist}} == Further reading== *Adams, J.A. 1986. ''Dirt''. College Station, Texas : Texas A&M University Press ISBN 0890963010 *Soil Survey Staff. ([[1975]]) ''Soil Taxonomy: A basic system of soil classification for making and interpreting soil surveys.'' USDA-SCS Agric. Handb. 436. U.S. Gov. Print. Office. Washington, DC. *Soil Survey Division Staff. ([[1999]]) ''Soil survey manual''. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. *Logan, W. B., Dirt: The ecstatic skin of the earth. 1995 ISBN 1-57322-004-3 *Faulkner, William. Plowman's Folly. New York, Grosset & Dunlap. 1943. ISBN 0-933280-51-3 *Jenny, Hans, Factors of Soil Formation: A System of Quantitative Pedology 1941 *[http://jan.ucc.nau.edu/~doetqp-p/courses/env320/lec1/Lec1.html Why Study Soils?] *[http://www.hort.purdue.edu/newcrop/tropical/lecture_06/chapter_12l_R.html Soil notes] *{{web cite |url=http://www.mvm.usace.army.mil/Readiness/97flood/flood.htm|title=97 Flood |publisher=USGS |accessdate=2008-07-08}} Photographs of sand boils. * Oregon State University's [http://forages.oregonstate.edu/is/ssis/main.cfm?PageID=3 Soils] (wiki) * [http://www.soil-net.com/ Soil-Net.com] A free schools-age educational site teaching about soil and its importance. * [http://www.landis.org.uk/ LandIS Soils Data for England and Wales] a pay source for GIS data on the soils of England and Wales and soils data source; they charge a handling fee to researchers. * [http://www.landis.org.uk/soilscapes/ LandIS Free Soilscapes Viewer] Free interactive viewer for the Soils of England and Wales * Geo-technological Research Paper, IIT Kanpur, Dr P P Vitkar - Strip footing on weak clay stabilized with a granular pile http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?journal=cgj&volume=15&year=1978&issue=4&msno=t78-066&calyLang=eng == External links == *[https://www.soils.org/ Soil Science Society of America] * [http://www.percolationtest.com/ Percolation Test] Learn about Soil, Percolation, Perc and Perk Tests. *[http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx USDA-NRCS Web Soil Survey] Inventory of the soil resource across the U.S. * European Soil Portal [http://eusoils.jrc.ec.europa.eu/ EUSOILS] (wiki) * [http://www.wossac.com/ Wossac] the world soil survey archive and catalogue. * [http://www.supersqr.com/vegetable-blog/"Soil texture tests] {{Geotechnical engineering|state=collapsed}} [[Category:Land management]] [[Category:Soil| ]] [[Category:Soil science]] [[ar:تربة]] [[ay:Laq'a]] [[bn:মৃত্তিকা]] [[zh-min-nan:Thô͘]] [[bs:Tlo]] [[bg:Почва]] [[ca:Sòl]] [[cs:Půda (pedologie)]] [[cy:Pridd]] [[da:Jord]] [[de:Boden (Bodenkunde)]] [[et:Muld]] [[el:Έδαφος]] [[es:Suelo]] [[eo:Grundo]] [[fa:خاک]] [[fr:Sol (pédologie)]] [[gl:Solo]] [[ko:흙]] [[hr:Tlo]] [[id:Tanah]] [[is:Jarðvegur]] [[it:Suolo]] [[he:קרקע]] [[kk:Жер]] [[lv:Augsne]] [[lt:Dirvožemis]] [[hu:Talaj]] [[mk:Почва]] [[ml:മണ്ണ്]] [[ms:Tanah]] [[nl:Bodem]] [[ja:土壌]] [[no:Jord]] [[nn:Jord]] [[pl:Gleba]] [[pt:Solo]] [[ro:Sol (strat al Pământului)]] [[qu:Allpa]] [[ru:Почва]] [[simple:Soil]] [[sk:Pôda]] [[sr:Едафски фактори]] [[sh:Tlo]] [[fi:Maalaji]] [[sl:Prst (pedologija)]] [[sv:Jord (mark)]] [[tl:Lupa]] [[th:ดิน]] [[vi:Đất]] [[tg:Гил]] [[tr:Toprak]] [[uk:Ґрунти]] [[yi:באדן]] [[bat-smg:Dėrva]] [[zh:土壤]]