Martin Kussmaul graduated in 1991 from the University of Konstanz, Germany with a degree in Hydrology. He then moved to the University of Hamburg where in 1994 he received a PhD in microbial ecology. Since 1995 he has been employed at the Institute of Soil Science at the University of Hamburg, where he produced this paper with his colleague at the institute, Alexander Groengroeft, and Dr Harald Koethe of the Federal Institute of Hydrology, Koblenz, Germany.