The WormEx II experiment to raise awareness about the importance of healthy soils and of their hydrological functions

Healthy soils provide many ecosystem services, among which some relevant ones belong to the hydrological sphere. In fact, healthy soils feed and filter freshwater reserves, whereas degraded soils can pollute water resources and make them unavailable or harmful to humans and plants. Besides, healthy soils are effective for both climate change mitigation, being the largest terrestrial carbon pool on the planet, and adaptation, thanks to their capacity of absorbing and retaining water thus reducing the hazard of floods and droughts.However, these characteristics are nowadays endangered due to several challenges deriving from mismanagement of the limited soil resources, the consequent soil degradation phenomena (viz soil sealing, erosion, loss of biodiversity and of organic matter) often lacking the necessary awareness and visibility.Aiming at contributing to disseminate the importance of healthy soils for the society and at highlighting the hydrological functions of an healthy soil, we designed the WormEx II experiment, that is an educational experiment to be performed in high-school classes. The experience takes the participants along the footsteps of Charles Darwin, who, studying the activity of worms, showed how great changes in Nature are often the result of the continuous superimposition of minimal processes. Researchers, teachers, high-school and university students set up a participatory experiment to repeat Darwin’s observations on the ability of annelid digging activity to bury abandoned bodies on the soil surface. By this experiment, students will observe how soils with different annelid activity behave and how the annelid activity increases the soil infiltration capacity.