1. Research Fellow, School of Agriculture, Forest and Horticultural Crops Research Centre, Univ. of Ghana, P.O. Box LG 1195, Legon, Accra, Ghana (corresponding author).
2. Lecturer, Dept. of Agricultural Engineering, School of Engineering, Univ. of Energy and Natural Resources, P.O. Box 214, Sunyani, Ghana.
3. Senior Scientist, Faculty of Science and Technology, Dept. of Agroecology, Aarhus Univ., P.O. Box 50, DK-8830, Tjele, Denmark.
4. Senior Lecturer, Dept. of Agricultural Engineering, School of Engineering Sciences, Univ. of Ghana, P.O. Box LG 77, Legon, Accra, Ghana.
5. Research Fellow, School of Agriculture, Soil and Irrigation Research Centre, Univ. of Ghana, P.O. Box LG 1195, Legon, Accra, Ghana.
6. Professor with Special Responsibilities, Faculty of Science and Technology, Dept. of Agroecology, Aarhus Univ., P.O. Box 50, DK-8830 Tjele, Denmark.