Editing Loam

{{Short description|Soil composed of similar proportions of sand and silt, and somewhat less clay}}
{{Other uses}}

[[File:SoilTexture USDA.svg|thumb|Soil types by clay, silt and sand composition as used by the United States Department of Agriculture]]
'''Loam''' (in geology and soil science) is [[soil]] composed mostly of [[sand]] ([[particle size]] > {{convert|63|µm}}), [[silt]] (particle size > {{convert|2|µm}}), and a smaller amount of [[clay]] (particle size < {{convert|2|µm}}).{{Cn|date=June 2022}} By weight, its mineral composition is about 40–40–20% concentration of sand–silt–clay, respectively.<ref name="KaufmannCleveland" >{{cite book |last=Kaufmann |first=Robert K. |author2=Cutler J. Cleveland |title=Environmental Science |publisher=McGraw-Hill |pages=[https://archive.org/details/environmentalsci0000kauf/page/318 318–319] |year=2008 |isbn=978-0-07-298429-3 |url-access=registration |url=https://archive.org/details/environmentalsci0000kauf/page/318 }}</ref> These proportions can vary to a degree, however, and result in different types of loam soils: sandy loam, silty loam, clay loam, sandy clay loam, silty clay loam, and loam.<ref name="KaufmannCleveland" />

In the [[USDA|United States Department of Agriculture]], [[soil texture|textural classification triangle]], the only soil that is not predominantly sand, silt, or clay is called "loam". Loam soils generally contain more nutrients, moisture, and [[humus]] than sandy soils, have better drainage and infiltration of water and air than silt- and clay-rich soils, and are easier to [[tillage|till]] than clay soils. In fact, the primary definition of loam in most dictionaries is soils containing humus (organic content) with no mention of particle size or texture, and this definition is used by many gardeners. The different types of loam soils each have slightly different characteristics, with some draining liquids more efficiently than others. The soil's texture, especially its ability to retain nutrients and [[Ecohydrology#Soil moisture dynamics|water]], are crucial.<ref>{{cite web|author=R. B. Brown|date=September 2007|title=Soil Texture|url=http://nmsp.cals.cornell.edu/publications/factsheets/factsheet29.pdf|access-date=June 16, 2021|work=Agronomy Fact Sheet Series: Fact Sheet SL-29|publisher=[[Cornell University]], Department of Crop and Soil Sciences}}</ref> Loam soil is suitable for growing most plant varieties.

[[Bricks]] made of loam, mud, sand, and water, with an added binding material such as rice husks or straw, have been used in construction since ancient times.

==Classifications==
Loam soils can be classified into more specific subtypes. Some examples are sandy loam, silt loam, clay loam, and silty clay loam. Different soil phases have some variation in characteristics like stoniness and erosion that are too minor to affect native vegetative growth but can be significant for crop cultivation.<ref>[[United States Department of Agriculture]] Soil Survey, 1943</ref>

==Use in farming==
[[File:Lancashire Loam - geograph.org.uk - 999357.jpg|thumb|Fine, loam-rich field ideal for farming vegetables in the UK]]
Loam is considered ideal for gardening and agricultural uses because it retains nutrients well and retains water while still allowing excess water to drain away.<ref>B. Rosie Lerner, "[https://www.purdue.edu/hla/sites/yardandgarden/what-is-loam/ What is Loam?]", [[Purdue University]] Consumer Horticulture, 6 January 2000. Retrieved 5 March 2017.</ref> A soil dominated by one or two of the three particle size groups can behave like loam if it has a strong granular structure, promoted by a high content of organic matter. However, a soil that meets the textural (geological) definition of loam can lose its characteristic desirable qualities when it is compacted, depleted of organic matter, or has clay dispersed throughout its fine-earth fraction.{{Clarify|date=April 2012}}

For example, pea can be cultivated in sandy loam and clay loam soils, but not more compacted sandy soils.<ref>{{cite web |title=Field Pea: Agronomy |url=https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/sandy-loam}}</ref>

==Use in house construction==
{{main|Earth structure}}
Loam (the high-humus definition, not the soil texture definition) may be used for the construction of houses, for example in loam [[Timber framing|post and beam]] construction.<ref name=Schittich>{{cite book |last=Schittich (Ed)|first=Christian Schittich|title=Building Simply|date=2001|publisher=Birkhäuser Architecture |isbn=3764372710 |pages=38–42}}</ref> Building crews can build a layer of loam on the inside of walls, which can help to control air humidity. Loam, combined with straw, can be used as rough construction material to build walls. This is one of the oldest technologies for house construction in the world. Within this there are two broad methods: the use of [[rammed earth]], or unfired bricks ([[adobe]]).<ref>Gerhard Koch, [http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.508.6174&rep=rep1&type=pdf "Loam Construction – from a niche product to an industrial building system"]. Tokyo: Action for Sustainability – The 2005 World Sustainable Building Conference in Tokyo, Japan, September 2005. Retrieved 17 December 2012.</ref>

<gallery>
File:Michelau Fachwerkdetail.JPG|Loam with timber framing ([[Michelau in Oberfranken]], Germany, 2007)
File:000410 Lehmhütte in der Nähe von Baligród.JPG|House with loam ground floor ([[Baligród]], Poland, 2012)
File:Biesenthal eldest house from 1707 (1).jpg|Loam-timber-framed 1707 house, under restoration ([[Biesenthal]], Germany, 2006)
File:Djenné Moschee.jpg|[[Great Mosque of Djenné]] (Mali, 2004)
</gallery>

==See also==
* {{annotated link|Loess}}
* {{annotated link|Grain size}}
* {{annotated link|Soil texture#Soil texture classification|Soil texture}}

==References==
{{Reflist}}

==External links==
{{Commons category}}

{{Soil type}}
{{Geotechnical engineering}}
{{Authority control}}

[[Category:Types of soil]]
[[Category:Soil]]