Garden Tool Set

Opal Earthworm Survey

Opal are well known for their open air surveys that everyone can take part in. I decided that I'd like to know more about the soil in our garden and provide records for the survey. They even kindly provided the pH strips, which surprisingly I didn't have lying around at home.

I began by digging a hole - 20cm x 20cm by 10cm deep. 20cm is the width of the spade blade - which made it nice and easy. I collected lots of data for the survey - which I've included below. For this post I'll concentrate on the soil data - which is what I was most interested in.


Soon after we moved here I found out how horrid the soil is in our garden. Many hours were spent digging and the more I dug the harder it got - the gardening books are right: clay soil is heavy soil. We definitely had clay soil! I checked on the British Geological Survey website and found that the clay was part of the Oxford Clay Formation. This is mudstone, siltstone and sandstone. Interestingly it shows that this sedimentary bedrock formed approximately between 154 to 164 million years ago in the Jurassic Period and that our local area would have been shallow seas at this point.

Following the field guide from the Opal website, I placed a piece of soil into a cup - around 1cm of soil. I then covered the soil piece with water and gave it a jolly good stir for around 1 minute. Now, take care to ensure it's a jolly good stir and not a moderate or calm stir - I may be making that part up, but it's definitely more fun if you give it a jolly good stir :)

Then, as you can see in the photos above, I dipped the pH strip into the water for around 3 seconds before running some clean water from the same bottle over it to clean it. I then held it to the sunlight, as per instructions, and awaited my fate.

For comparison, I've shown a fresh pH strip to the left and the used pH strip to the right. It seems that our silty clay soil is middling between 6.5 (alkaline) and 7 (acidic). This is ideal really because neutral soil is easiest for the majority of plants to use the nutrients in the soil. Clay soil is known to have a good lot of nutrients held within them. It is now the plan to fork over the border and introduce the compost from the local household waste facility, which I will then fork over again. This should act to break up the clay into smaller crumbs, which should - over time - make for a really good soil.

For those of you that would like to know the full results from this survey; please see below:

Here's the worm that I found in the soil. My inexpert eye and the Opal guide seem to suggest that this is a grey worm (Aporrectodea caliginosa).

Survey questions	Your answers
Sampling date	2013-04-13
Name of site	My Garden
Postcode	SN12 7JG
Lat	51.37589
Lng	-2.12459
Start importance	Y
Start outdoor activities	Y
Participation	In my own
Done survey before	N
Done survey before other
Id earthworms before	N
LocationMethod	Postcode
FinalPosition	Lat: 51.37589 Lng: -2.12459
Surrounding area	Suburban
Sampling site	Garden
Nearest road	Less 20
Nearest road name	Blackmore Road
Pollutants	None
Weather	Some clouds
Plant cover	Half earth half plants
Taken photo site	N
Shallow immature count	0
Shallow adult count	1
Timing	Less 3 minute
Deep immature count	0
Deep adult count	0
Other immature count	0
Other adult count	0
Taken photo soil pit	N
Plant roots	A few roots
Soil objects	Construction material
Soil hardness	Easy
Soil fizz	N
Soil moisture	Moist
Soil pH	PH7
Soil texture	Silty clay loam
Soil smell	No smell
Soil colour	Colour b
Beetles	0
Flies	0
Larvae	0
Bugs	0
Other insects	0
Snails	0
Slugs	0
Spiders	0
Other non insects	0
Taken photo (other)	N
Where found (shallow)	Soil from pit
Length (shallow)	8
Shallow worm taxa id	11

To do a survey yourself, click through to the Opal site and view all of the available surveys.