Influence of compost supplemented with jatropha cake on soil fertility, growth, and yield of maize (zea mays L.) in a degraded soil of Ilorin, Nigeria

L) yield in a degraded soil and their residual effects on soil fertility in Ilorin, Nigeria. Methods Field trials were conducted at Kwara State University Teaching and Research Farm, Malete, in 2016/2017 cropping season. The treatments consisted of control, un-amended compost Grade B supplemented with Jatropha cake AJ (30% Grade B + 70% JC) at 1.5 t/ha, BJ (30% Grade B + 70% JC) at 2.0 t/ha, CJ (50% Grade B + 50% JC) at 2.5 t/ha including NPK at 60 kg N/ha. The treatments were arranged in a randomized complete block design (RCBD) and replicated three times. Results Maize grain yield (3.1 t/ha) was obtained from CJ at 2.5 t/ha this was significantly (p < 0.05) greater than that of NPK treatment (2.2 t/ha) after the first cropping. At second trials, maize grain yield values gotten from CJ at 2.5 t/ha were also significantly (p < 0.05) greater than that of NPK values. Treatments CJ at 2.5 t/ha significantly (p < 0.05) improved soil pH, available P and exchangeable K. Conclusion Fertilizer 50% Grade B + 50% Jatropha cake at 2.5 t/ha had a significant and positive effect on soil fertility after harvesting of maize when compared with NPK in both cropping.