Methods

We used a simple procedure to investigate the food preference of red wigglers, Eisenia foetida. First, we established that the worms would prefer soil that included organic matter over simple potting soil by setting up a bin where half of the area was potting soil while the other half was a potting soil/grass mixture. We placed ten worms on the dividing line between the two soil types, placed the container into a black plastic bag to prevent light penetration, and left the container undisturbed for 48 hours. We then checked the bin and found that all of the worms were located in the soil/grass mixture. This data supports our hypothesis that red wigglers have a soil preference, and thus we were able to begin our experiment.

The experiment consisted of 3 sets of 2 bins. Each bin had two different soil types on either half of the container. The sets of containers were combinations of the following:

1. A grass/soil mixture vs. potting soil


2. A newspaper/soil mixture vs. potting soil


3. A grass/soil mixture vs. a newspaper/soil mixture


The potting soil served as the control in this experiment. In order to control variables that could influence the soil preference of earthworms, the soil volume, texture, and moisture was kept constant for each trial. Each bin contained 225 grams of soil and 500mL of water. In the bins with a grass or newspaper soil mixture, 500 mL of either grass or newspaper was added and mixed throughout the soil. We placed 10 worms in the middle of each bin and covered the bins with a black plastic bag. We checked the bins 48 hours later and counted the worms in relation to their location. If a worm was found on the dividing line between two soil types, the worm was not recorded as having a preference for either soil. The location of the worm within the bin was used to determine food preference. This process was repeated twice to collect ample data to speculate on the food preference of red wigglers.

The pH and nitrogen levels of each soil type were also measured using a soil testing kit.

Testing the pH level of the soil.


Testing the nitrogen level of the soil.