I’m sitting in the ancient Freelander on the edge of a field called Sheepwalks, listening to the soundtrack from O Brother, Where Art Thou? and watching the John Deere combine glide by. It’s as stately as the Queen Mary, and the barley disappears in front of its prow like the curl of an ocean wave. The beginning of harvest is a prayerful moment in the farming year, and we have much to be thankful for. We sold half the crop ‘forward’, back in December, at £170 a ton.

Two years ago, we sold a ton of barley for £80. Our gratitude doesn’t stop there: we’re getting more than three tons an acre and the moisture level is 14.5%, which means we don’t have to run the fuel-hungry and noisy dryer night and day. But before I start singing Keep On The Sunny Side, I have to admit that higher grain prices owe a lot to the bio-fuels market. What once seemed like the answer to a farmer’s prayers is turning out to be a catastrophe that could turn our oceanic John Deeres into Titanics. And I can’t lull myself into believing that this year’s price for my wheat and barley is going to pay off the farm overdraft. Corn may be making record prices, but so are all the things we have to buy to produce the corn: sprays, diesel… you name it.

The Soggy Bottom Boys sing I am a Man of Constant Sorrow as the auger spews the barley into the trailer. Another southern voice rings in my head. This morning on the Today programme, I heard a clip from Al Gore sounding like ‘Thought for the Day’. In his soft Tennessee accent, he said: ‘We’re borrowing money from China to buy oil from the Persian Gulf to burn it in ways that destroy the planet. Every bit of that has to change.’ Mr Gore is urging the US to wean itself from its entire electricity grid to carbon-free energy within 10 years. He remembers that when it looked like the Russians were going to beat them to the Moon, the Americans rose to the challenge and got there first.

The likelihood of it happening isn’t great, what with the US national debt pegged at $9.4 trillion, and the running expenses of $16 billion a month for wars in Iraq and Afghanistan. I hear another southern voice every time I get in my car these days. My family become comatose when I praise Jimmy Carter for enacting the legislation that lowered the speed limit to 55 miles an hour following the 1973 oil embargo. I preach about how road deaths plummeted, oil consumption was reduced dramatically, and the planet was a better place. Bless that Georgia boy’s heart, I say, and remind folks that he also installed solar panels on the White House. But yesterday my husband, an 80-mile-an-hour man, told me I’d got it wrong: it wasn’t Mr Carter but Richard Nixon who signed the 55-mile an hour law.

I didn’t believe him, but desperate Googling proved him right. Much as I hate to praise Mr Nixon, he was brave to do it. It infuriated speed-addicted Americans far more than ping-pong with the Chinese. No politician has the guts today. Imagine if the G8 leaders agreed to a 55mph (90kph) speed limit on all European roads just for the month of August as a trial. The planet could catch its breath and oil prices would tumble.

The main problem is psychological. We’re all in too big a hurry. We want high-speed trains to Paris that carve 20 minutes off our trips to Paris (then wait an hour in the taxi queue at the Gare du Nord). But high-speed trains are just as energy-greedy as planes. We want to drive 80 miles an hour to London (and sit in gridlock once we get to the Embankment). I think it’s time for a global Go Slow. I can help the speed-addicted through withdrawal. Climb up here on the combine with me. Happiness is gliding through cornfields at three miles an hour with Alison Krauss singing. The song is Down to the River to Pray.