Before joining LSU, he worked as a Research Scientist at the University of Göttingen and University of Kassel in Germany, and at the Virginia Polytechnic Institute & State University in Blacksburg, USA. Xu received his B.S. degree from Beijing Forestry University, China, with a focus in forest soils, and his M.S. and Ph.D. degrees from the University of Göttingen, with a focus in soil chemistry, physics, and hydrology. His research has covered a range of topics including hydrologic and biogeochemical processes and modeling, watersheds, surface water quality, riverine nutrient and sediment transport, land use and climate change effects on carbon and nitrogen cycles, and GIS/remote sensing applications in surface hydrology and natural resources.