Mycorrhizal fungi form partnerships with plant roots and profoundly influence soil health and carbon storage. Different types of these fungi (arbuscular, ectomycorrhizal, and ericoid) work differently and create distinct soil environments with varying impacts on nutrient availability and carbon cycling. Researchers have now developed a unified framework and an experimental system to better understand and measure these effects, which could improve our ability to manage soils and predict ecosystem responses to environmental changes.