How could you find out whether and earthworm eats soil or not?

To determine if an earthworm eats soil, you can conduct a simple experiment by placing an earthworm in a controlled environment with soil and observing its behavior over time. By weighing the soil before and after a set period, you can check for any loss in mass, which would indicate that the earthworm is consuming the soil. Additionally, examining the earthworm's castings can provide insight into its diet, as the presence of soil particles in the castings suggests that it has ingested soil.