The term “kelp” originated in Europe and was used to describe the ash of burnt seaweeds. During the 16th century seaweeds were harvested and burnt for sodium compounds (soda), iodine, and potassium compounds (potash). Seaweed potash and soda were used to make glass, soaps, fertilizers, and eventually gunpowder. The seaweeds that contained the most soda and potash were said to be the brown seaweeds, thus Laminariales became commonly known as “kelps.”
Germany, in the late 1800s, was the largest producer of mineral potash in the world. After the start of the first world war, Germany put an embargo on potash, cutting off the largest consumer of potash, the Americans.
In response, the Americans industrialized kelp harvesting in southern California to produce potash for gunpowder.
The kelp harvesting industry has since declined as other sources of compounds were found. However, it was this industrial wartime in the early 1900s that led to intense kelp forest research which has continued to this day.
Hercules Powder Company (South Bay Historical Society)