Southavong S, Khammingsavath K and Xayyavong D 2015: Biochar and biodigester effluent increase the yield of Yardlong bean (Vigna unguiculata) and improve soil properties. Livestock Research for Rural Development. Volume 27, Article #33. Retrieved , from http://www.lrrd.org/lrrd27/2/siso27033.html