Wilhelm Knop

Wilhelm Knop (1817 to 1891) was a German agrochemist who, with Julius von Sachs, co-founded modern water culture through experiments growing crops in nutrient solutions. Born at Altenau, the son of a forester, he studied natural sciences at Göttingen and Heidelberg, taught at the commercial college in Leipzig, and became a professor at the University of Leipzig in 1861 and honorary full professor of agricultural chemistry in 1880. From 1856 to 1866 he also headed the scientific department of the Möckern Agricultural Experiment Station near Leipzig. With von Sachs he identified nitrogen, phosphorus, sulfur, potassium, calcium, magnesium and iron as essential elements for plant nutrition, and Knop solution, a four salt mixture with a trace of iron, is still used in plant biology. He wrote specialist books on agricultural chemistry and fertilisation.