@ARTICLE {KWARI:2009, title = {Relation of yields of soybean and maize to sulphur, zinc and copper status of soils under intensifying cropping systems in the tropical savannas of north-east Nigeria}, author = {Kwari, J. * and Kamara, A. and Ekeleme, F. and Omoigui, L. }, journal = {Journal of Food, Agriculture and Environment}, year = {2009}, volume = {7}, number = {1}, pages = {129--133}, issn = {1459-0255}, }