Editing Machair (section)

==Geography==
[[File:Abhainn Mhuilean Domhnuill - geograph.org.uk - 1364230.jpg|thumb|A stream cutting through the machair highlights a sandy composition]]
Machair differs from the [[Links (golf)|links]] on the east coast of Scotland in having a lower mineral content, whereas the links are high in [[silica]].<ref name=glas>{{cite journal |url=http://www.glasgownaturalhistory.org.uk/machair/ohdear.pdf |title=Oh, dear! What can the Machair be? |first=John A. |last=Love |publisher=Glasgow Natural History Society |access-date=18 December 2013}}</ref> Machair plains are highly [[calcareous]], with [[calcium carbonate]] concentrations ranging from 20% to 80% on the beaches, and decreasing further away from the coast.<ref name=glas/> The [[pH]] of a machair is typically greater than 7, i.e. it is [[Alkalinity|alkaline]].<ref name=snh/>

The inside of a machair is often wet or marshy, and may contain lochs.<ref name=snh/><ref>{{cite book |url=https://books.google.com/books?id=YPQaFxH-AZYC&pg=PA141 |title=A Nature Conservation Review: Volume 1 |first=Derek |last=Ratcliffe |publisher=Cambridge University Press |year=2012 |page=141|isbn=9780521203296 }}</ref>

===Formation===
The modern theory of machair formation was first put forward by [[William MacGillivray]] in 1830.<ref name=glas/> He worked out that shell fragments are rolled by waves towards the shore, where they are further broken up. The small shell fragments are blown up the beach to form mounds, which are then blown inland.<ref name=glas/>

===Humans===
Human activity has played an important role in the creation of the machair. Archaeological evidence suggests that some trees were cleared for agriculture as early as 6000 BC, but there was still some woodland on the coast of [[South Uist]] as late as 1549.<ref name=glas/> Seaweed deposited by early farmers provided a protective cover and added nutrients to the soil.<ref name=glas/> The grass is kept short by [[cattle]] and [[sheep]], which also add trample and add texture to the [[Grassland|sward]], forming tussocks that favour a number of bird species.<ref name=glas/>

The [[soil]] is low in a number of key [[nutrient]]s, including trace elements such as [[copper]], [[cobalt]] and [[manganese]], requiring cattle to be fed supplements or taken to summer pastures elsewhere.<ref name=glas/> The sandy soil does not hold nutrients well, making artificial fertilisers ineffective and limiting the crops that can be grown to certain varieties of [[oats]] and [[rye]], and [[Bere (grain)|bere barley]].<ref name=glas/>