Editing Marl (section)

===Historical use in agriculture===
Marl is one of the oldest [[soil amendments]] used in agriculture. In addition to increasing available calcium, marl is valuable for improving [[soil structure]] and decreasing soil acidity{{sfn|Mathew|1993}} and thereby making other nutrients more available.{{sfn|Winiwarter|Blum|2008}} It was used sporadically in Britain beginning in prehistoric times{{sfn|Dodgshon|1978}} and its use was mentioned by [[Pliny the Elder]] in the 1st century.{{sfn|Frossard|Bünemann|Jansa|Oberson|2009}} Its more widespread use from the 16th century on contributed to the early modern agricultural revolution.{{sfn|Dodgshon|1978}}  However, the lack of a high-energy economy hindered its large-scale use until the [[Industrial Revolution]].{{sfn|Winiwarter|Blum|2008}}

Marl was used extensively in Britain, particularly in [[Lancashire]], during the 18th century. The marl was normally extracted close to its point of use, so that almost every field had a marl pit, but some marl was transported greater distances by railroad. However, marl was gradually replaced by lime and imported mineral fertilizers early in the 19th century.{{sfn|Shannon|2020}} A similar historical pattern was seen in Scotland.{{sfn|Dodgshon|1978}}

Marl was one of a few soil amendments available in limited quantities in the southern United States, where soils were generally poor in nutrients, prior to about 1840.{{sfn|Sheridan|1979}} By the late 19th century, marl was being mined on an industrial scale in [[New Jersey]]{{sfnp|Geological Survey of New Jersey|1880|p=184}} and was increasingly being used on a more scientific basis, with marl being classified by grade{{sfnp|Woll|1896|p=295}}{{sfnp|New Jersey State Centennial Board|1877|p=203}} and the state geological survey publishing detailed chemical analyses.{{sfnp|Geological Survey of New Jersey|1887}}