Fresh water (inlad swamp) have great potential for the development of the agricultural sector, the common constraints of lowland swamps are flooding during the rainy season and drought during the dry season. This study aims to analyze the effect of NPK and Bio N+ fertilizer formulations on pH, saturated water content, and C-organic content of planting media in a floating raft system during the vegetative period of rice plants. This study was conducted in Parigi Village, Daha Selatan District, Hulu Sungai Selatan Regency, South Kalimantan. This study used a one-factor Randomized Block Design with treatments namely F₀ (control), F₁ (NPK 100%), F₂ (NPK 75% + Bio N+), F₃ (NPK 50% +  Bio N+), F₄ (NPK 25% + Bio N+), and F₅ (Bio N+), repeated four times, resulting in 24 experimental units. The results showed that NPK and Bio N+ fertilizer formulations affected pH, saturated water content, and C-organic content of the planting media. At 2 and 4 WAP (weeks after planting), the highest C-organic content was in the 75% NPK + Bio N+ fertilizer formulation, while at 6 and 8WAP, the highest C-organic content was in the 50% NPK + Bio N+ fertilizer formulation. The 50% NPK + Bio N+ fertilizer formulation was able to maintain the highest pH of the planting media until the end of the observation, and the application of 100% NPK fertilizer resulted in the highest saturated water content of the planting media at 8 WAP.