Alex James: Modern farmers are really just playing the stock market

Harvest time in Norfolk: Wheat mainly, plus rapeseed and sugarbeet on 2,000 acres, about three square miles, enough land to justify owning the machinery that makes it all efficient and easy – a combine, big tractor, grain drier and storage sheds.

I realised after visiting this particular farm that actually growing stuff isn't the tricky bit. Machines and experts take care of all that for the farmer. Data from last year's harvest is fed into the crop-sprayer, telling it to squirt more juice on patches where the yield was low. A consultant agronomist regularly inspects the crops, suggesting ways to combat pests and wring the most out of the soil without wrecking it.

That's all straightforward. The really clever bit is deciding what to grow, when to harvest and when to sell. Modern farmers are playing the stock market, really – trading commodities and betting on futures. Behind every smart combine harvester, although not necessarily at the wheel, is a smart cookie. My host foresaw the rise of a middle class in China and surmised that grain prices would rise as a result. He raised finance to buy enough land to grow wheat on a practical scale and is grinning as grain prices shoot through the roof – though possibly not just because of Chinese ciabattas.

He obviously really enjoys the intellectual, gaming side of agriculture, the risk. The day before, a thunderstorm had passed within two miles of the rapeseed. The ripe seed-pods are very brittle and a direct hit by a thunderstorm might have reduced the yield from six tonnes per hectare to four, which is the difference between a healthy profit and an unsustainable loss. Then there is the question of when to sell. The grain will keep once it's dried. The clever guys wait till the price is right. Once the bets are placed, large-scale arable farming is as thrilling as the Grand National and as hi-tech as Formula One. It just all happens very slowly.

Cheese or beans?

Sheep prices have crashed. On our 200 acres, I've been looking at working with a contractor to turn a couple of fields over to arable. The soil around here is heavy, so we'd have to spend a fair bit on organic fertiliser and weed control, but they're doing well with weird beans next door. I've been and had a quick illicit nibble. Very good. Will the Chinese be wanting beans on their toast or cheese, I wonder.

Reindeer patter

The Norfolk farmer's wife had the best hustle I've heard for ages. She kept a pair of reindeer. They make good pets and can fetch £700 an appearance at shopping centres at Christmas time. That's got to be more than celebrities get paid for doing pantomime. They're fully booked.