(b. Mausitz, near Pegau, Saxony, Germany, 21 October 1831; d, Bernburg, near Halle, Germany, 24 September 1895)
Hellriegel was educated at the famous Saxon Fürstenschule in Grimma, then studied chemistry at the Forestry Academy in Tharandt, near Dresden. Here he established a close relationship with the agricultural chemist Adolf Stöckhardt, who soon entrusted him with the duties of an assistant. He thus received manifold stimulation for his later activity in the field of practical chemistry established by Liebig.
Stöckhardt quickly recognized Hellriegel’s special capabilities and as early as 1856 arranged his appointment to the board of directors of the new agricultural research institute at Dahme in the Nieder Lausitz. There, as a young scholar of twentyfive, Hellriegel was able to devote himself to research problems in plant physiology and to concentrate on questions, first raised by Liebig, concerning the nutritive requirements of certain cultivated plants. He was especially interested in the improvement of sandy soils, often found in central and northern Germany, which presented great difficulties if used intensively. For his work, then regarded as epochal, he was named titular professor by the Saxon government in 1860.
In 1873 the government of Anhalt-Bernburg named Hellriegel director of the agricultural research institute at Bernburg. But Hellriegel, who still had no experimental equipment at his disposal, had at first to content himself with functioning as a governmental adviser on agricultural questions. He used the time to travel about the small dukedom to impress upon the peasants, through word and deed, the need for progressive agriculture.
Through the support of the German sugar industry syndicate—beet sugar had already replaced cane sugar as the preferred sweetener in Germany—in 1882 Hellriegel opened a research facility at Bernburg. There his chief undertaking was research on the conditions required by sugar beets, questions of nitrogen supply in plants playing a major role. In doing this work, which above all served to improve sandy soil and involved the experimental use of sterilized sand, Hellriegel and his colleague H. Wilfarth discovered that certain leguminous plants, cooperating symbiotically with bacteria enclosed in nodules on their roots (Rhizobium frank), assimilate nitrogen from the air and convert it into a utilizable bound form.
Hellriegel reported this for the first time in an address at the fifty-ninth meeting of the German Society of Scientists and Physicians at Berlin in 1886. With this pioneering discovery the success of his contemporary Albert Schultz-Lupitz in cultivating legumes, preferably the lupine, as an intermediate crop and notably in the hitherto relatively barren sandy soil, could be explained. Thereby the cultivation of intermediate crops as a scientifically investigated, systematically introduced measure for increased soil fertility acquired considerable importance.
Since Hellriegel’s work was closely followed abroad, it is not surprising that he received numerous honors. He was an honorary member of the Royal Swedish Academy of Sciences, the Royal Society of London, the Paris Academy of Sciences, and the French National Society of Agriculture. The Bavarian Academy of Sciences in Munich awarded him the Liebig gold medal.
Hellrieger’s main Work is Untersuchungen über die Stickstoffernährung der Gramineen und Leguminosen, supp, issue of Zeitschrift des Vereins für die Rübenzuckerindustrie im Zollverein (1888), written with H. Wilfarth.
Secondary literature is H. Haushofer, Die deutsche Landwirtschaft im technischen Zeitalter (Stuttgart, 1963), pp. 163–164; O. Keune, ed., Männer, die Nahrung schufen (Berlin, 1952; 2nd ed., 1954); C. Leisewitz, “Hellriegel,” in Allgemeine deutsche Biographie, L (Leipzig, 1905), 169–171; O. Lemmermann, “Die Untersuchungen Hellriegels über die Stickstoffernährung der Gramineen und Leguminosen,” in Zeitschrift für Pflanzenernährung, Dügung und Bodenkunde, 45 (1936), 257; L. Schmitt, “Hellriegel,” in Neue deutsche Biographie, VIII (Berlin, 1969), 488; and H. Wilfarth, “Professor Dr. Hermann Hellriegel,” in Landwirtschaftliche Presse, no. 90 (1895),