Hermann Hellriegel (October 21, 1831 – September 24, 1895)[1] was a German agricultural chemist who discovered that leguminous plants assimilate the free nitrogen of the atmosphere.

In 1857 he became director of the agricultural experiment station of Brandenburg and Niederlausitz at Dahme, from which he resigned in 1873, and in 1882 accepted a similar post at Bernburg, where he died.

The question of the ability of leguminous plants to use the nitrogen of the air had long been one of inquiry, and its settlement by him marked an epoch in the agricultural world.

The important parts of these experiments he published in Untersuchungen über die Stickstoffnahrung der Gramineen und Leguminosen (Investigations into the Nitrogen assimilation of the Gramineae and Leguminosae; Berlin, 1888), and Ueber Stickstoffnahrung landwirtschaftlicher Kulturgewächse (On Nitrogen assimilation in agricultural crops; Vienna, 1890).

They found that peas growing in inoculated soils produced root nodules, and after an initial period of nitrogen deficiency, turned green and made thrifty growth.