The Natural History Museum are running a survey called Earthworm Watch and would like people to investigate contrasting habitats to see what differences are found. All details are on their website.
There is an additional survey using similar patches of soil and then adding material to one and seeing if there are any earthworm differences after a month. This would be interesting from a dig/no dig viewpoint. I’m sure we could use samples from nearby plots where one has been converted to no-dig a while ago. The majority of details are on the link ‘Instructions Booklet PDF’.