1. University of Kassel Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics Steinstrasse 19 37213 Witzenhausen Germany
2. Ruhr-Universität Bochum Institute of Geography Department for Soil Science and Soil Ecology 44780 Bochum Germany
3. Université de Dédougou / Université Ouaga 1 Pr Joseph KI-ZERBO BP 7021 Ouagadougou 04 Burkina Faso
4. University for Development Studies Faculty of Agriculture Post Office Box TL 1350 Tamale Ghana
5. International Water Management Institute Water Quality, Rural-Urban Linkages Program P.O. Box 2075 Colombo Sri Lanka