Earthworm Compost Survey Results


Keiron Derek Brown

The Earthworm Compost Survey has now been re-launched as part of World Earthworm Day.

In 2011 we first ran the Earthworm Compost Survey. We had a great response, over 225 people told us about their compost and 209 people found earthworms in their compost! The survey was re-launched in September 2014 and 563 responses in total were received before it closed in 2015. This report presents the findings of this survey to date.

Are worms currently present in your compost bin/heap?

Of the 563 responses we received, 524 (93%) compost bins/heaps were confirmed to contain earthworms. Only 5% did not contain earthworms (including cases where earthworms had previously been present and since disappeared).

Compost bun presence

How did the earthworms colonise your compost bin/heap?

We found out that most earthworms are not placed in the compost bins by enthusiastic gardeners but instead they just turned up in the system (89%).

Compost bin colonisation

Some species of earthworm specialise in feeding in compost (also manure, sewage treatments works and other places with large amounts of organic matter). They prefer warm and moist environments with a ready supply of fresh organic material. They can very rapidly consume this material and also reproduce very quickly. These species are known as compost earthworms and tend to be bright red in colour and stripy. Compost earthworm species include Eisenia fetida (Brandling or Tiger Worm) and Dendrobaena veneta. You can read more about different types of earthworm on the Earthworm Ecology web page.

How old is your compost bin/heap?

Compost bin age

What type of bin do you have?

Compost bins that are open to the ground were by far the most popular system (72%) that was reported in the survey.

Compost bin type

In the case of sealed compost bins where the earthworms had not been introduced deliberately, earthworms were also found. Little is known about how earthworms are able to colonise these sealed bins, it may be that the earthworms were arriving in the bins through garden waste.

What do you put in your compost bin?

We found that the most popular things people put in their compost were: kitchen green waste (95%), garden green waste (94%) and tea bags (83%). Around 20% of compost bins/heap were treated with an accelerator (including urine). We also found that the use of slug pellets within compost heaps/bins is relatively low as only 7 cases (1%) were reported (and 3 of these did not have earthworms at the time of the survey). 

compost bin contents

Another interesting result was the number of people who put citrus fruits in their compost bins; we found that 62% of respondents added them to their compost. Surprisingly this did not seem to affect the earthworms, because they were still recorded in the compost with citrus. This throws doubt on the commonly held belief that citrus fruits make conditions too acidic for earthworms and is something we would like to investigate further.

Where is your compost system located?

Compost system locations

Take part in the relaunched Earthworm Compost Survey here

Creative Commons License
This work was created by Keiron Derek Brown on behalf of the Earthworm Society of Britain and is licensed under a Creative Commons Attribution 4.0 International License.