Last week I watched Valentine Warner's What to Eat Now seasonal cookery programme. In this episode, Valentine visited a biodynamic farmer, who explained some of the principles of biodynamic farming. The farmer -- whose name I forget, but who seemed a very nice, cheery sort of chap -- showed Valentine how he makes his compost heap. Since I started growing my own veg, I've become a bit of a compost nerd^1^, and I was whistling appreciatively at the sight of the lovely ingredients the farmer had on his heap. There was lots of greenery, including nettles which contain iron and other useful minerals, cow pats, straw and other goodies. It had the makings of wonderfully rich, nutrient-packed compost. And then he pulled out a box of containers and explained that he would put into a hole made in the heap a pinch of yarrow which had been stored in a stag's bladder for a year (it may have been some other internal organ, I forget) hung up in the air, and then buried for a year. Or something like that. I'm afraid that I'm not certain of the details, because my mind was being boggled, and I was watching carefully to see what Valentine's response would be. He was terribly polite, but said it sounded a bit "witchy".
Quite. My favourite fictional witches -- those in Terry Pratchett's Discworld novels -- rarely do any actual magic. Instead, a large component of their work involves what they refer to as 'headology'. This is the practice of getting people to believe something so strongly that it becomes real for them. Headology is cousin to the placebo in modern medicine, though rather more diverse. Some witches, like Nanny Ogg, perfect a cosy, homely persona, so that women in labour are convinced that giving birth is the easiest and most straightforward thing in the world. Others, like Granny Weatherwax maintain such a terrifying demeanour that people stop being ill out of sheer fright. Some, like Eumenides Treason, construct a mythical reputation with a collection of dribbly candles, plastic skulls and stick-on facial warts bought from Boffo's Joke Shop. All of these elaborate practices are maintained to convince their clients to believe that a particular story is true and real. It's fictional of course, but I'm fairly sure that aspects of it would work in the real world, just as we know that the placebo effect exists.
You probably see where I'm going with this. Headology works because people have minds, and I'm certain that it would have no perceptible effect on beetroot. The compost was responsible for his great beetroot, and the "witchy" bits were entirely optional. The only person being worked on by the yarrow-in-stag's bladder routine is the farmer. It's a shame really, because there are lots of very sensible and scientifically robust practices in biodynamic farming, like looking after the soil well, and making great compost. But then they go and spend a lot of time and energy on something that must have no measurable effect on the quantity or quality of the crop. Of course, I've had limited exposure to biodynamic methods, so it could be that the farmer featured in the program was on the far fringe of the movement.
^1^ I know, along with all my other domains of nerdery... I'm a nerd of all trades and a master of none. ↑