| since 2022 | Managing Director of the Institute of Tropical Agricultural Sciences (Hans-Ruthenberg Institute) at the University of Hohenheim |
| 2020-2022 | Deputy Managing Director of the Institute of Tropical Agricultural Sciences (Hans-Ruthenberg Institute) at the University of Hohenheim |
| 2016-2019 | Member of the steering committee of the Hohenheim Research Center for global food security and ecosystems |
| 2012-2015 | Director of the Tropenzentrum of the University of Hohenheim |
| since 2014 | Director of the Anton & Petra Ehrmann-Stiftung Research Training Group: Water - People - Agriculture (WPA) |
| 2014-2016 | Managing Director of the Institute for Plant Production and Agroecology in the Tropics and Subtropics at the University of Hohenheim |
| since 2010 | Chairman of the board of ATSAF eV. |
| since 2008 | Director of the international master program "AgriTropics" and speaker for all International Master Programs. |
| since 2007 | Full Professor at the Agricultural Faculty of the University of Hohenheim, Stuttgart. |
| 2006 | Co-organizer of the Conference on International Agricultural Research for Development - "Tropentag 2006". October 11-13 2006 in Bonn. |
| 2006 | Co-organizer and resource person of the DAAD-DIES-Seminar: "Proposal Writing for International Research Projects," Second part, 26th-30th, June, 2006, Nairobi, Kenya |
| 2005 | Co-organizer and resource person of the DAAD-DIES-Seminar: "Proposal Writing for International Research Projects," First part, 12th-17th, June, 2005, Nairobi, Kenya |
| 2002-2007 | Webmaster for the research group "Plant Nutrition in the Tropics and Subtropics" PITROS |
| 2001 |
Co-organizer of the Conference on International Agricultural Research for Development - "Deutscher Tropentag 2001". October 9-11 2001 in Bonn. |
| 2001-2007 |
Webmaster and Curriculum Coordinator for the Postgraduate Study Program ARTS - Agricultural Sciences and Resource Management in the Tropics and Subtropics |
| 2001-2007 |
Assistant Professor at the Agricultural Chemistry Institute, Faculty of Agricultural Sciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany |
| 1999-2001 |
Assistant Research Professor for Bioclimatology and Agrohydrology at the Royal Veterinary and Agricultural University (KVL), Department of Agricultural Sciences, Taastrup, Denmark - also web master |
| 1997-1999 |
Post-doctoral fellow in WARDA's Systems Analyses Department as a crop modeler. |
| 1999 |
Organization of a Training Course in Crop Modeling in collaboration with Wageningen Agricultural University. WARDA 22-30th March 1999. |
| 1998 |
Organization of a Mini-workshop on Rice-Weed competition modeling. WARDA, 25-27th October 1998 |
| 1995 |
Participation in the organization and implementation of an International Rice Production Course 15.5.-26.5. 1995 |
| 1994/5 |
Participation in the organization and implementation of an "International Workshop on Irrigated Rice in the Sahel - Prospects for sustainable Development", 27.3.-31.3.1995 St. Louis, Sénégal. |
| 1993 - 1995 |
Co-project coordinator of the GTZ - Special Project: "Salinity Tolerance in Irrigated Rice in the Sahel" at WARDA’s research station in St. Louis/Ndiaye, B.P. 96, Sénégal. |
| 1993 - 1996 |
Research assistant at the Institute for General Botany and Botanical Garden, Dept. Plant Physiology |
| 1992 - 1993 |
Research consultant for the West Africa Rice Development Association (WARDA), St. Louis, Sénégal. |
| 1989 |
3 month work experience at the Wau Ecology Institute, Wau, Papua New Guinea |