In wildlife gardening, it is so easy to only think about all the wildlife that lives above ground. But imagine all the life that lives beneath the soil. We may come across some of it when we are digging, but what is it? How is it faring? And how can you help it?

Well, this weekend I'm going to try something I have never done - being a fearless hunter, I'm going to go seeking worms. And I'm going to invite you to do the same!

The thing that inspired me to go underground exploring was an email I received telling me about the 'Big Worm Dig'. It is an initiative set up by Riverford Farm, an award-winning organic farm, in collaboration with the University of Central Lancashire.

What they are asking is for people to dig a one foot by one foot square of soil and count and identify which worms they find. Now you may, like me, think that your worm identification skills aren't quite up to the task, but Riverford have created a wonderful information pack to help us all. With it, you will suddenly realise that the off-colour worms you sometimes find aren't sick, they're the Green Worm. Or you might find those with a pink tip, which will be either the Rosy-tip or the Grey Worm. See, they're not all just 'earthworms'!

In order to take part, you need to go onto the Riverford website here. Or you can leapfrog the opening pages to the log-in page here. Don't be put off by the fact that you have to put in name and address - it is worth it and you will be emailed an electronic booklet showing you how to take part and how to identify your worms. And they say it only takes about 20 minutes.

Now they're not after the worms of your compost heap (which I find are the only worms I've ever photographed, so that's the photo you're getting!) - we know that compost heaps can be stuffed with them.

No, this survey is looking to see how worm-rich our soils are across the country.

I'll let you know how I get on - I think I'm bound to learn something from the exercise. And I'd love to know if any of you give it a go too.

If you want to drop by my RSPB wildlife gardening blog, it is updated every Friday, and I'd love to see you there - www.rspb.org.uk/community/blogs/hfw