This study assesses the application of horsetail ash as a sustainable soil stabilizer additive in infrastructure materials, highlighting the significance of environmentally friendly practices in construction. The horsetail plant (Equisetum Hyemale) which is recognized for its abundant silica content, was incinerated at different temperatures to produce ash for investigation. The study included initial analysis by visually inspecting and weighing samples, then conducting ignition tests to measure carbon content and evaluate pozzolanic properties. Subsequently, Energy Dispersive X-Ray Analysis (EDX) and Scanning Electron Microscopy (SEM) were used to examine the elemental composition and morphology of the ash. Ignition tests showed that higher incineration temperatures are associated with lower carbon content and a rise in crystalline silica forms. Incinerating at 700 ℃ effectively decreased carbon content while maintaining the amorphous silica structure, making it the ideal temperature for bulk incineration. The study shows that horsetail ash, particularly when processed correctly, has great potential as an eco-friendly and economical additive for improving soil characteristics in geotechnical uses.