Pls can someone identify this root?
 

New to gardening I was digging over a patch of garden to put spuds in. I discovered what I thought was an old bit of rubbery, orange, plastic tube, about 1.5cm in diameter. As I "followed" it I realised that it was an old root as there aren't any plants near it. The root split length-ways easilly and was white with orange stripes. My spade cut through it easilly. Any ideas? (Is it something nasty???)

Do you have any idea what was there before you started planning a veg space? How long was the piece of root? Was there any sign of regrowth? If not, then it was probably dead anyhow.

Hi,
I've only had the house for a few months, so I don't know what was there before. It would have been very overgrown if it hadn't been for the 5 (yes, 5!) layers of old carpet the previous owner had put down. It was a veg patch once before. I've pulled about 4 feet out and I can see it was still going. The wasn't any evidence of it trying to grow, but it'd didn't really seem dead. (Not sure what dead would look like though.)

Thanks Chris,

I have investigated a little more, well, a lot more, and have found my way to a very old rhubarb patch. Thanks for your time and suggestion though.
Happy gardening.