How to use hydrogeochemical diagrams to understand soil salinity in a Altiplano Wetland?

Altiplano wetlands are extreme environments where hydrology, geochemistry, ecology, and climate interact in complex and often poorly constrained ways. In northern Chile, these systems support unique biodiversity, regulate water availability in closed basins, and sustain cultural practices that have persisted for centuries. At the same time, they are increasingly exposed to climate change, chronic water scarcity, and expanding mining activities. Despite their importance, soil processes in these ecosystems—particularly the spatial organization of salinity and ionic composition—remain underrepresented in environmental research, partly due to methodological fragmentation across disciplines.

This contribution reflects on an interdisciplinary attempt to “learn to fly” by borrowing tools from hydrogeology and water quality studies and applying them to soil science. The study focuses on the Salar de Huasco, an Altiplano wetland in the Chilean North. The main objective was not only to characterize soil salinity patterns, but also to explore whether classical hydrogeochemical visualization tools such as Piper and Stiff diagrams could provide intuitive insights into soil ionic composition in a spatially heterogeneous environment. Soil samples were collected at 15 locations across the salt flat and grouped by cardinal sector (north, south, east, and west). Laboratory analyses quantified major soluble cations and anions, including calcium, magnesium, potassium, chloride, sulfate, and carbonate species. These data were processed in R to generate Piper and Stiff diagrams adapted to soil chemistry, a step that required methodological adjustments and conceptual translation from water to soil systems. The results reveal a contrast between variability and consistency: while total salt concentrations differ substantially across the Salar, the relative proportions of cations and anions remain similar in most sampling points. This finding suggests shared geochemical controls at the system scale, despite spatial heterogeneity in salinity intensity. This work illustrates the value of interdisciplinary learning. Applying familiar tools in unfamiliar contexts involves uncertainty, trial and error, and continuous questioning of assumptions. However, it also opens space for methodological creativity and clearer communication. Piper and Stiff diagrams emerge as powerful visual tools for bridging disciplines and making complex soil salinity patterns more accessible, offering a promising pathway for future research and monitoring of Altiplano Wetlands.