@INPROCEEDINGS {KAMARA:2006b, title = {Deterioration in soil fertility as a consequence of cropping intensification in the savannas of northeastern Nigeria}, author = {Kamara, A. and Kwari, J. * and Omoigui, L. }, booktitle = {Sustainability-its impact on soil management and environment. Proceedings of 17th Triennial conference, International Soil Tillage Organization. 28th August-3rd September, Christian-Albrecht’s Universitaet, Kiel, Germany}, year = {2006}, pages = {584--592}, }