Effect of nitrogen sources on cassava yields in Sierra Leone

Abstract Two experiments were conducted on Njala upland soils to investigate the effects of various N sources on cassava. Highest utilization indices (UI) were observed when (NH.)‐SO, and urea were applied in three split applications. Utilization indices of ‘cocoa’ cassava remained below unity indicating that it is a low yielding cultivar since high yielding cultivars have UI near or greater than unity. Application of various N sources did not increase fresh tuber yield in either experiment indicating that under conditions of this study cocoa cassava has a low N requirement.