L. Keabetswe*, G. C. Shao, J. Cui, J. Lu, T. Stimela Key Laboratory of Efficient Irrigation-Drainage, Agricultural Soil-Water Environment in Southern China, Ministry
1 of Education, College of Agricultural Engineering, Hohai University, Nanjing 210098, P. R. China
2 Department of Crops and soil Science, Botswana University of Agriculture and Natural Resources, Gaborone, Botswana