We call it dirt, we scrape it off our shoes, and we rarely give it a thought — yet almost all of our food, and much of life on land, depends on the thin skin of soil covering the planet. This episode digs into what soil actually is, and why it matters far more than its humble reputation suggests.

You'll come away understanding how soil forms over centuries, why a single handful teems with billions of living things, how it stores water and carbon, and why soil erosion is one of the quiet threats to feeding the world.

Talking Science is sponsored by Kinsoft. Visit www.kinsoft.com.au

Further reading: CSIRO – "Soil" research pages; FAO – "The state of the world's soil resources"; Australian Government – "Soil health".