Sufficient nutrient availability is crucial for plant growth and reflects the ecological functions of soil. In modern agriculture, which emphasizes efficiency and sustainability, interactions among soil, minerals, organic matter, and microorganisms play a key role in enhancing nutrient uptake by plants, including corn, which relies heavily on potassium, phosphor, and magnesium. Wet tropical soils are generally nutrient-poor due to leaching, necessitating approaches that integrate soil amendments with biological agents. Pyroclastic material, as a local source rich in primary minerals, has the potential to improve soil fertility depending on its weathering rate. The weathering process is accelerated by root exudates and soil microbial activity. Among functional microbes, potassium-solubilizing bacteria (PSB) play a crucial role by releasing potassium from insoluble minerals through biochemical mechanisms, thereby enhancing nutrient use efficiency in corn. In addition, humic substances contribute to improving soil structure, increasing cation exchange capacity, and facilitating the release of micronutrients. This study aims to evaluate nutrient uptake in corn plants following the application of pyroclastic material, humic substances, and potassium-solubilizing bacteria. The study was conducted in the greenhouse of DITSL, Faculty of Agriculture, IPB University, using a completely randomized design (CRD) with 24 treatment combinations. Pyroclastic material was applied at varying doses, while humic substances and potassium-solubilizing bacteria (PSB) were applied at a constant base dose. The parameters observed included plant height, leaf number, stem diameter, plant biomass, and nutrient uptake. The results showed that the combination of pyroclastic material (450 g) with humic substances and PSB produced the highest plant growth compared to other treatments. However, no significant differences were observed in leaf number and stem diameter. Nutrient concentration significantly affected the uptake of calcium, potassium, and magnesium.