The Australian National Soil Archive is a collection of over 100,000 soil samples from 30,000 sites across Australia, dating back to the 1920s. The archive is a "library of what the land was like at different points in time" and holds secrets of the past, including samples from the Simpson Desert Expedition in 1939. The archive is currently being digitized with the help of citizen scientists, and new technology is being used to analyze soil samples, including a method that can predict soil carbon content in 20 seconds. The goal is to track soil health and guide policy and action to sustain the nation's fertile soils, particularly in the face of global fertilizer shortages.