One of the most ubiquitous wet granular matter surrounding us is soil, which plays an essential role in keeping a sustainable ecosystem for all of us. We consider growing roots as active particles with size and shape evolving with time. Using X-ray tomography to track the positions of artificial soil particles as well as the morphology of the active ones, we are trying to address the question: How do this type of active particles cooperate with each other or with the environment?

An answer to this question builds the bridge between soft matter physics and ecology. The goal is to build physical models for simulating ecosystems at a larger scale. This project is in collaboration with Matthias Schröter from Erlangen and Ina Meier from Göttingen. Below are two videos showing the growth of Mung bean seeds in ~100 hours.