Rusty Sue investigates: Cross country mud in all its forms

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Rusty Sue investigates: Cross country mud in all its forms


Cross country in the UK would not be what it is without mud. Let’s just let that stand as fact. Debatable, of course, is the quality of that mud

What, you’ve never discussed the properties of that mud with your clubmates after a race? You know, whether it was gloopy or slippy, grippy or sticky? Smelly, perhaps?

I have. And to indulge my curiosity even further, I talked mud with some specialists. One, an international turfgrass agronomist (yup, you read that right), and another, a soil scientist for the Scottish Environment Protection Agency (and a cross country runner, too!).

Turns out it’s not really that complicated

‘Very broadly mud is a high clay content in the soil,’ Gordon Jaaback, the turfgrass agronomist, tells me when I sneak out of the office for a chat about mud.

I start getting even more of a kick out of the conversation when we get into percentages.

‘You’ve got soils made up of clay and sand, generally. If it’s sandy there’s no stickiness and you don’t have a problem.’

‘But as soon as the clay content starts getting up to 30-40% it starts getting very sticky and loamy.’

Maybe next time you’re heaving your spikes out of the mud, just think about it in terms of “a problem” and have a guess as to the clay content percentage. That’s worth a few seconds of distraction.

And did you know that the perception of mud can be illusory?

This can happen when the ground you’re running on has, for one reason or another, become compacted and water cannot drain. As a result, it sits on the surface and the top layer becomes saturated. As Jaaback says: ‘in simple terms, it would be considered muddy, although it might not be muddy in the true sense of the word.’

Getting philosophical about mud. Now we’re talking.

Illuminating on a more practical level, however, is Karen Dobbie’s guide to what you might see if you examine different types of soil under a microscope.

Soil scientist reveals all

The soil scientist and Edinburgh AC runner tells me that the scientific texture of the soil is determined by the different proportions of grains and the grain sizes:

‘There are basically two end-members¹ in this spectrum,’ she says. ‘You get sandy particles, which tend to be round, and when you get a lot of them together, there are spaces between them, so if it rains, that lets water drain and it means it’ll drain quickly.

‘And the other side of that are clay particles, which are smaller and tend to be flatter so you get smaller spaces between them, and if any water comes in that doesn’t drain as well.’

Turns out that quite a bit of our cross country experiences will be shaped by how well soil on a given course drains or how much it is damaged.

Dobbie recalls her worst cross country experience relating to soil damage. This involved running over a field that hosted livestock, meaning it was ‘poached’ – what soil scientists call ‘trampled’. This, in turn, meant the rain didn’t drain, with oxygen therefore struggling to get into the oil (because spaces between the soil particles were waterlogged).

The result was that the soil was ‘anaerobic’, so it smelt. ‘A lot,’ says Dobbie.

Sound familiar?

Not one of the more pleasant sides of cross country, but heck, it’s all part of the glorious experience that is UK cross country racing. And next time that mud you’re churning through has a bit of a fragrance, you can think about the size of the soil particles and the sizes between them, what percentage clay content it might be, how the soil could have come to be so poached and so forth.

Either that or: “Pain is inevitable, suffering is optional.”²

Words by @RustySue
Image from Belper Harriers

¹This is a proper term. I Googled it, and got lost in scientific papers about soil. Did you know that soil classification has progressed with the introduction of computers in the mid-20th century to the point where algorithms can be used to organise soil information into clusters that correspond with soil classes? And that algorithms such as fuzzy k-means perform well, but can be biased by extreme data? Me neither. If you’re interested, check out the August 2014 issue of the Geoderma Journal.

²Personal favourite. It’s from Buddha.