Agriculture and Biological Chemist. He is best remembered as the "father of the fertilizer industry" for his major discovery of nitrogen as an essential plant nutrient and his creation of the Law of Minimum, which describes the effect of individual nutrients on crops. He believed that nitrogen must be supplied to plant roots in the form of ammonia, and recognized the possibility of substituting chemical fertilizers for natural (animal dung, etc.) ones. Additionally, he developed a manufacturing process for beef extracts and founded the Liebig Extract of Meat Company that later trademarked the Oxo brand beef bouillon cube. He was fascinated with chemistry as a child and at the age of 13 he experienced the "year without a summer" attributed to a series major of volcanic eruptions that culminated with the 1815 eruption of Mount Tambora in the Dutch East Indies which resulted in major food shortages across the Northern Hemisphere in 1816 and became known as the last great subsistence crisis in the Western world. He became an apprentice to a pharmacist in Heppenheim, Germany and attended the University of Bonn and later the University of Erlangen in Nuremberg, Germany, where he studied for his Doctorate degree. He left Erlangen in March 1822 partly due to his involvement with the radical nationalist student organization Korps Rhenania and to further advance his studies in chemistry. In the autumn of 1822 he went to Paris, France on a grant from the Hessian government to study chemistry and in 1824 he became a professor at the University of Giessen in the city of Giessen, Germany, where he established the world's first major school of chemistry. In 1832 he founded and edited the journal "Annalen der Chemie," which became the leading German language journal of chemistry. In 1835 he invented a process for silvering that substantially improved the quality of mirrors. In 1837 he was elected as a member of the Royal Swedish Academy of Sciences and in 1845 he was given the title of Freiherr, or baron. In 1852 he received an appointment from the King Maximilian II of Bavaria to the University of Munich where he remained until his death at the age of 69. As a result of his contributions, nitrogen fertilizers are now widely used throughout the world, and their production is a substantial segment of the chemical industry. His major works include "Organic Chemistry in its Application to Agriculture and Physiology" (1840), "Animal Chemistry, or Organic Chemistry in its Application to Physiology and Pathology" (1842), and "Familiar Letters on Chemistry" (1843). After World War II the University of Giessen was renamed Justus Liebig University Giessen in his honor.