Wednesday 1 January 2014

Garden earthworm bothering part 1: sampling


I have sulking at home since the Soil Biodiversity Group earthworm fieldwork ended so between Christmas and the New Year I decided to get out into the garden and hunt for earthworms - one of the great things about earthworms is that they are active even during winter so long as the ground is not frozen. There was some difficulty in that my sister had borrowed the spade so I had to make do with a fork and trowel, not ideal for making neat soil pits. Also, my ‘assistant’ who was curious to what I had been up to in fields these past weeks turned up without his warm clothes and waterproofs so it ended up being a rather brief survey which I will continue in the New Year.

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Andrew, my somewhat reluctant ‘assistant’ Quote: “You did this all day in a field!? Would drive me round the bend”

Garden earthworm survey - pouring the mustard solution
But despite this I did let him pour the mustard solution

I used the standard method for earthworm surveys, details of which can be found on the Earthworm Society of Britain website. The first pit was dug in the scruffy bit of grass that passes for a lawn and I was surprised to find the soil was drier, less clayey and less compacted than I expected. It was also without structure, no layers of top soil and subsoil like I have been used to in the fields and woodland, just loose soil on top a layer of rubble – sadly typical of suburban soils - but there were still earthworms. Sadly the mustard solution did not produce any earthworms although I was not surprised as the soil is rather shallow and I have not seen many of the distinctive casts the anecic types make.

An earthworm in its burrow
An earthworm in its burrow in the soil removed from the lawn

Sadly the mustard solution did not produce any anecic earthworms although I was not surprised as the soil is rather shallow and I have not seen many of the distinctive casts they make on the lawn.The next pit was made in one of the raised vegetable beds and even this highly disturbed area produced five earthworms, although unfortunately all immature specimens which could not be identified to species. As we were losing daylight and Andrew was getting cold we had a quick look in some microhabitats rather than start another soil pit. As expected the compost heap produced lots of the Compost or Brandling Worm Eisenia fetida which lives in areas of high organic matter, it has a stripy appearance when moving and they exuded a unpleasant yellow fluid when handled.

Compost worm Eisenia fetida
A handful of Eisenia fetida

Under my log pile I found two small red worms and a larger pale pink one which along with the two adult earthworms from the soils pits were retained for identification. In part two I will go through the steps in identifying these earthworms.

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