Guardian of a hidden universe

Wall, a soil ecologist and environmental scientist at Colorado State University in Fort Collins, has come to this site about an hour east of the campus to collect data for one of her latest experiments. Alongside her own experiments, Wall has become an ambassador for soil science and conservation - at a time when soil ecosystems are being devastated by forces such as erosion, pollution, pesticides and climate change. Soil degradation over the past two centuries or so has released billions of tonnes of stored carbon into the atmosphere, and this discharge could accelerate, speeding up climate change.