Man of science

Plant ecologist Ken Thompson discusses the subject of his latest book – compost

Ken Thompson

'A bit of understanding about the science of the garden makes you less anxious, which means more relaxed and in the end a happier gardener.'

Why a book on compost?

Much of what is written about compost is too dependant on stuff previously published. I wanted to look at the scientific research.

Who do you consider is doing good research on composting?

The Centre for Alternative Technology (CAT) in Wales is doing brilliant stuff. The people are passionate about it, yet very down to earth so not unrealistic about what gardeners can do. As I am a keen gardener, their research chimed with what I found worked. They had already published a small booklet and I added to it – and I looked at other scientific literature.
I like to keep my ear to the ground and interpret fundamental scientific research and also look at other papers on unrelated matters. Lots of people, for instance, say how good paper and cardboard is for the compost heap, but then someone said: ‘What about waxed paper?' This set me thinking. Wax is organic, so it should be fine, and I actually managed to find some good science that had been done on waxed cartons that showed it was.

The role of calcium is not often covered in books on compost. Have you explored it much?

Some pioneering research on calcium had been done at the University of Sheffield about 10 years ago. We looked at decomposition of native plants in bags and how fast they decomposed. The results couldn’t be explained by carbon : nitrogen (C:N) ratios alone, but we found the plants high in calcium decomposed more quickly than those low in calcium.
Then, completely separately, I recalled examining a PhD thesis at Writtle College looking at proprietary compost additives. A box was analysed and found to have a lot of garden lime in it. It's worth remembering that simple garden lime is an inexpensive compost additive.

The science could be considered a little offputting?

The average gardener may think it’s not for them, but a bit of understanding about the science of the garden makes you less anxious, which means more relaxed and, in the end, a happier gardener.

Ken's latest book

What's your own garden like?

By Sheffield standards, it’s quite large and on a steep slope with the house at the top giving a nice view. There’s an area of lawn with some long grass as a meadow, wildlife feature. I’ve a double compost bin of my own construction made from old timber. There are also several shrubs and trees that I’ve grown myself from seed: birches, a davidia and a mulberry. I get a real feeling of achievement from seed raising. The garden has been terraced, so I have space for a veg plot. Last year was a particularly good year for my parsnips – they appear to be very drought-tolerant. The wild parsnip is found in dry places.

What are you planning next?

My next book, which is about biodiversity – what it is and what happens. It's plant-based, but will include a few animals too.

Look further

Ken Thompson is a plant ecologist and senior lecturer at the University of Sheffield. He promotes the science behind gardening to the general reader. His book Compost – the natural way to make food for your garden explains the scientific principles clearly and easily in a distinctive humorous style. It is published by Dorling Kindersley, price £12.99.