Historical Information

Ever since ancient classical times, materials that contained potassium have been used as fertilizers, such as excrement, bird manure, and ashes (1), and these materials certainly contributed to crop growth and soil fertility. However, in those days people did not think in terms of modern chemical elements. Even an excellent pioneer of modern chemistry, Antoine Laurent de Lavoisier (1743–1794), assumed that the favorable effect of animal excrement was due to the humus present in it (2). Humphry Davy (1778–1827) discovered the chemical element potassium and Martin Heinrich Klaproth (1743–1817) was the first person to identify potassium in plant sap (3). Home (1762, quoted in 4) noted in pot experiments that potassium promoted plant growth. Carl Sprengel (1787–1859) was the first to propagate the idea that plants feed from inorganic nutrients and thus also from potassium (5). Justus Liebig (1803–1873) emphasized the importance of inorganic plant nutrients as cycling between the living nature and the inorganic nature, mediated by plants (6). He quoted that farmers in the area of Giessen fertilized their fields with charcoal burners’ ash and prophesied that future farmers would fertilize their fields with potassium salts and with the ash of burned straw. The first potash mines for the production of potash fertilizer were sunk at Stassfurt, Germany in 1860.