Mineral weathering replenishes the supply of inorganic nutrients that sustains terrestrial life on Earth. The soil microbiome, including fungal communities, contributes to weathering by disrupting, dissolving, and extracting nutrients from mineral grains. Fungi seek out nutrients and water sources by spreading networks of exploratory hyphae across a soil landscape. However, identifying the mechanisms used by fungi to transform minerals to extract rock-derived nutrients remains challenging, especially in natural soils that span different climates, rock types, and ecosystems. The goal of the research is to understand how fungi interact with abiotic environments to initiate mineral weathering and form soil in Earth’s critical zone. This project will utilize recent advances in high resolution microscopy and mass spectrometry to examine fungi interacting with mineral surfaces at micro-to nano-scale resolutions. The results will demonstrate how new technologies can promote the progress of the earth and environmental sciences in combination with an Integrated Critical Zone Model. The project findings will bring economic and societal benefits with respect to soil preservation, agricultural activity, and bio-engineering given the ubiquitous nature of soil fungi in the environment. This research will be integrated with the educational goal to diversify, recruit, and retain community college students in the (geo)sciences academic pipeline by implementing: Soils & Outreach for Integrated Learning & Self-Efficacy (SOILS) Bridge. The bridge program will enhance academic and social resources for incoming college students through tiered mentoring, training in the field and lab, and K-12 outreach.

This work will probe into fungal-mineral interactions across spatial scales to answer unresolved questions related to fungal impact on mineral transformations and contributions to nutrient cycling. The research objectives are to: 1) Assess weathering of natural soils and incipient transformation of mineral substrates buried in mesh bags across landscapes that span bioclimatic (desert to coastal rainforest) and topographic (summit to drainage) gradients, 2) Differentiate weathering agents and the initial stages of fungal-driven weathering in field systems using microscopy, mass spectrometry, and elemental analyses of deployed minerals, and 3) Quantify mass transfer rates of mineral elements normalized to mineral-fungi contact areas determined from field-deployed mineral samples and subsequently upscaled using soil process models. The study will provide unprecedented insight into how fungi respond to climate, topography, and nutrient availability and will offer mechanistic insights into processes that upregulate weathering in natural soils.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.