Science Buddies: "Ask an Expert"

My kids did the project that tests which diets affect earthworms and the soil they enrich. We did coffee grounds, garlic & onion peels, egg shells, leaves & grass, and a control pot with nothing but soil and worms. The worms died in all the pots except the one with coffee grounds and leaves and grass. Could you give me some suggestions on why this may have happened? The worms in these two pots did reproduce but not much. One pot reproduced 13 worms and the other about 5. Another thing we noticed is the worms that were still alive seemed to weigh less than when we originally started. I have read many times that egg shells are a good diet for earthworms so why did these worms die? The only thing I could think of is the egg shells needed to be pulverized for better consumption. Please help so we could analzye all this date and summarize what should have happened. We need to know why our project did turn out as expected.

Thanks,
Alexandria

Hi Alexandria,

The earthworms in the control pot and the egg shells did not have anything to eat so could not survive. Earthworms are strict vegetarians need a source of organic matter like leaves, grass, vegetable peelings or coffee grounds to survive and grow. They prefer grean leafy vegetables. Egg shells contain calcium carbonate, which is an essential nutrient for earthworms, but it doesn’t contain any organic matter. The garlic and onions do contain organic matter, but must also contain something that is toxic to earthworms.

The earthworm project on the Science Buddies website has been recently revised and no longer recommends using the control pot with no food, or the garlic and onions.

Donna Hardy