Abstract: Fertilization is crucial to crop productivity sustenance under continuous land-use, but crop response could vary widely in different agro-ecologies. Effectiveness of sole and combined organic fertilizer- O.F, 0.6% N; crystallizer- 8.83% P; muriate of potash- MOP- 49.8% K; triple superphosphate- TSP- 19.22% P and urea- 45% N (replicated thrice in randomized complete block design) for yam (Dioscorea rotundata i.e., TDr-99-6 and Dioscorea alata i.e., TDa-98/01176) performance were evaluated on Typic paleudalf (at Ibadan, Rainforest) and Arsenic haplustalf (at Abuja, Guinea Savanna) in Nigeria. Short-term and residual-effect differences in TDr-99-6 tuber yields were insignificant (p<0.05) while highest TDa-98/01176 yield (40.21 t ha-1) was obtained with urea at Ibadan. Residual effects of O.F+TSP enabled TDa-98/01176 to produce the highest yield (27.97 t ha-1) at Abuja. TDa-98/01176 out-yielded TDr-99-6 but with dry-matter contents being more dependent on fertilizer treatment. The hypothesis that O.F effects could improve with increased application rates needs to be tested.