"Terra Salis" is a photographic exploration of the complex issue of potash mining in Heringen an der Werra, located in eastern Hesse. The focus extends beyond the external scale of Germany's largest salt heap to also examine the transformative processes affecting the surrounding landscape and the environmental impacts of industrial activity on natural habitats. Central questions are raised about the human construction of landscapes and nature, and the legitimacy of our interventions in these spaces. The mined potash is primarily used as agricultural fertilizer, while the residual salt reshapes the visual and cultural character of the entire region. Parts of the underground tunnel system have been repurposed to store toxic waste from across the globe, making Heringen one of the most contaminated sites in the world. Furthermore, the discharge of potash effluent has led to the creation of an artificial inland salt flat, fostering a distinctive flora of salt-tolerant plants. Once an ecologically diverse river, the Werra is now the saltiest river in Europe due to these activities. Despite the environmental consequences, the potash industry remains a vital economic force and the region's primary employer. The work is divided into twelve sections, structured across three levels—above ground, underground, and an intermediate level connecting the two. Each level highlights different facets of the theme. A variety of photographic techniques and materials are used to provide a layered, multifaceted understanding of this intricate topic.