Translations:Manfred Klett: Von der Agrartechnologie zur Landbaukunst/232/en

The favourable pre-crop effect of legumes remained a riddle until the end of the nineteenth century, until in 1886 Hellriegel (1831–1895) published his discovery of the nitrogen-fixing nodule bacteria that live in symbiosis with the roots of legumes. Despite these insights from science and practice regarding the fixation of nitrogen from the air as a process occurring in the living realm, all zeal concentrated on the question of how the nitrogen of the air might be converted into the form of a salt by technical means, bypassing the living. For it was not only a matter of winning this most coveted of all fertiliser substances for agriculture, but equally for the production of explosives. The world's sole deposit of extractable nitrogen salts in the form of sodium nitrate is located in the Atacama Desert in Chile — a distant, exceedingly expensive source for the growing demand of the nineteenth century.