Nutrient management adopting various decision-support tools plays a key role in obtaining better rice yield. Thereby, three nutrient management strategies; i.e., Regional Soil Laboratory (RSL), Rice Crop Manager (RCM), and Farmers' Fertilizer Practice (FFP) for lowland rice production were tested. The experiment was laid out in an RCBD with four treatments and three replications. The treatments were T₀ = Control; T₁ = RSL; T₂ = RCM; T₃ = FFP. Results revealed that rice plants under FFP applied with higher amounts of N, P₂O₅, and K₂O significantly headed and matured late than unfertilized control and RSL but no significant difference from that of RCM. Rice plants under RCM developed significantly more productive tillers when compared to all other treatments except for RSL which produced a similar number of productive tillers. Rice plants under RSL obtained significantly higher grain yields but were comparable with RCM. The highest gross margin and highest return on investment (ROI) were obtained in plants under RSL with Php 65,226.73 ha^-1 and 90.55%, respectively while the control plants obtained the lowest gross margin of Php 9,294.44 ha^-1. The nutrient requirements of NSIC Rc176H should follow both RSL and RCM for excellent growth, better yield, and higher income. Therefore, RSL and RCM nutrient management decision tools are strongly recommended for rice farmers' adoption to assure of achieving better yield, high gross margin, and equitable ROI under irrigated lowland ecosystems