Field studies were conducted in 2012 and 2013 in the tropical rainforest zone of Nigeria to investigate the effects of a composted, pelletised organo-mineral fertiliser applied as an organic amendment at 5 metric tonnes (MT) ha–1 or at 10 MT ha–1 in four replications, on soil population densities of five genera of plant-parasitic nematodes and on crop yields of Telfairia occidentalis (fluted pumpkin). The experimental field was naturally infested with Meloidogyne incognita, Tylenchus spp., Helicotylenchus spp., Hirschmaniella spp., and Longidorus spp. The compost was applied as an amendment to soil planted with T. occidentalis 3 weeks after seedling emergence. At the end of both annual experiments, the addition of compost as a soil amendment resulted in 16.25 – 65.75% reductions in the populations of all five genera of plant–parasitic nematodes compared to an increase in each nematode population in the untreated control plots. There was also a higher crop yield of T. occidentalis in all eight treated plots compared to the control plots. Compost applied at 10 MT ha–1 reduced the soil populations of all nematode species significantly, with correspondingly higher yields of the crop compared to 5 MT compost ha–1 in both years of study. Correlation analysis showed that the population density of each nematode species had a negative effect on the cumulative leaf biomass (fresh weight) of the test crop. The results of this study suggest that nematodes constrained the production of T. occidentalis under continuous cropping and that a composted, pelletised organo-mineral fertiliser, applied as a soil amendment at 10 MT ha–1, suppressed soil populations of all five nematodes significantly and increased yields of T. occidentalis by 109 – 366% compared to the untreated control plots
