NATURE Special Feature 1 – Delving into the Mysteries of Soil! Earth’s soil is the foundation that supports biological activity, but what actually is it? Soil is a complex structure composed not only of minerals released by the weathering of rocks on Earth’s surface, but also of water, air, organic and inorganic matter, and microorganisms. Formed over long periods of time under the influence of climate, topography, and living organisms, among others, soil is a living system that governs ecosystems, supports biological activity, and plays an essential role in our lives as a place where food is produced. However, it has deteriorated significantly as human activity has intensified, and is also affected by climate change. People are now becoming aware of a crucial question: how can we maintain Earth’s soil?