Usman, M., F. Ibrahim, and S. O. Oyetola. 2018. “Sustainable Agriculture in Relation to Problems of Soil Degradation and How to Amend Such Soils for Optimum Crop Production in Nigeria”. International Journal For Research In Agricultural And Food Science 4 (1):01-17. https://gnpublication.org/index.php/afs/article/view/329.