Root-knot nematodes (RKN) severely reduce watermelon yields worldwide, despite its nutraceutical value. This study investigated the effects of rock dust (RD) and poultry manure (PM) amendments, applied singly or in combination, on RKN suppression and watermelon fruit yield enhancement. A two-trial field experiment was conducted utilizing a randomized complete block design with three replicates. The treatments included RD and PM each applied at 0, 2.5, or 5 t/ha and combined applications of RD and PM at 2.5 or 5 t/ha each. At 60-66 days post-inoculation, root galling and RKN population density were assessed alongside root-shoot weight. The results indicated that root galling in watermelons was reduced by 60-85 % and 67-89 % in the combined RD- and PMtreated plots across the 1st and 2nd trials, respectively, in contrast to the control plots. Likewise, the RKN population was suppressed by 94-99 % in treated plots in both trials, differing from the control plots. Notably, watermelon fruit yield was significantly higher (p < 0.05) in combined RD and PM treated plots, ranging from 24.7 to 33.7 t/ha and 34.6-46.5 t/ha in the 1st and 2nd trials, respectively, compared to control plots with 13.5 t/ha in the 1st trial compared to and 20.9 t/ha yield in the 2nd trial. In conclusion, our study indicates that coapplication of RD and PM effectively reduced RKN damage and enhanced watermelon fruit yield, providing a sustainable strategy for watermelon production.