Rice cultivation using a floating raft system is one alternative for agricultural development on peatland, as it enables crop production under flooded conditions. This study aimed to determine the effect of NPK and Bio N+ fertiliser formulations on phosphorus uptake in Ciherang rice plants cultivated using a floating raft system. The study was conducted in Parigi Village, Daha Selatan Sub-district, Hulu Sungai Selatan Regency, South Kalimantan, using a one-factor randomised block design with six treatments and four replicates, namely F0 (control), F1 (100% NPK), F2 (75% NPK + Bio N+), F3 (50% NPK + Bio N+), F4 (25% NPK + Bio N+), and F5 (Bio N+). The data were analysed using ANOVA, followed by a DMRT test at the 5% significance level. The results of the study showed that the formulation of NPK fertiliser and Bio N+ had a significant effect on the pH of the growing medium, the total P content of the growing medium, the total phosphorus content of the roots, the total phosphorus content of the plants, phosphorus uptake by plant tissues, and the dry weight of the above-ground biomass; however, it had no significant effect on the dry weight of the below-ground biomass. The Bio N+ treatment (F5) produced the highest total phosphorus content in the growing medium, roots and plants, whilst the combination of 75% NPK + Bio N+ (F2) resulted in the highest phosphorus uptake by the lower biomass. The highest phosphorus uptake by the upper biomass and the highest dry weight of the upper biomass were obtained in the 100% NPK treatment (F1). The results of the study indicate that the combination of the Bio N+ biofertiliser with a reduced dose of NPK fertilizer.