BBC2 aired 'A Farm for the Future' this week. (That was the iplayer link; here's a hopefully permanent download link.) Rebecca Hosking was born on a Devonshire farm and, on returning to it again, she has decided to try and find out how it might be run if the oil starts running out. (She's also done a fine write-up in the Daily Mail - a sentence I'm unlikely to say again in the near future.)

There are many great, graphic images in this, alongside the story of just how reliant on fossil fuels our farming is. A few quick thoughts: she tells us there are 150,000 farmers left - average age 60. "British farming has effectively been left to die." Well - that's what happens in a world of comparative advantage. Other countries can make the food, and we can sell financial servi... oh.

Rebecca's farm raise livestock: she talks to Fordhall Farm, who do the same. Most cattle producers expend the largest amount of energy and machine time keeping livestock indoors during the winter and producing hay for them to eat - so that they don't trample the fields that feed them into a mushed ruin. Fordhall's original owner, Arthur Hollins, learned a way around this over a lifetime's observing soil creation in woodland: the right combination of grasses. Twenty or so breeds carry out different tasks, including pulling up nutrients from deep down, and creating a soil that can stand up to cows' winter stompings. No hay, no heated winter shed - Arthur's two children now manage with one quad bike.

The most arresting image is two juxtaposed chunks of footage: one from ploughing on Rebecca's farm in the 80s, and one from today. (See pic.) No birds follow the tractor any more: the soil is dead - nothing more than a neutral medium for synthetic inputs. As Rebecca notes: 'The only way that modern agriculture can get away with killing the soil is through another use of a fossil fuel.' Chemical fertilizer: granules containing nitrates, phosphate and potash. Over 95% of all food grown in the UK is reliant on this. Without fossil fuels, we're going to need living soil again. Hollins used a lovely image: ploughing up living soil would be like tearing off human skin. I'm guessing being against ploughing could not have been much fun.

The rest of the programme talks about permaculture; there's some very interesting stuff, though it's hard to shake the feeling of 'forest gardens' as an Elysian mirage - and the one practitioner she speaks to only quotes 'theoretical' yields. Hmm. But there's a nice point toward the end: gardening, not farming, might be the future of food. The distinction between the two isn't just scale; it's the nature of the human input. As Rebecca notes, the attention to detail that experienced gardeners can apply means up to five times the yield per unit of land than a farm. The 'inverse size / yield relationship' has the same basis. Smaller farms are more productive because they tend to involve more human labour. (There's another post to be written about this: who in their right mind wants to work on the land? Most people get out when they can. Will this change? It certainly will if people starting going hungry, but... )

The programme left me wondering about our chances (again). Sulphurs spew out of oceanic hydrothermal vents, and whole ecosystems have evolved on them. Their culture is built on geothermal energy and nutrients, and knows little or nothing about the sun-powered ecosystems all around them. When those vents die, those ecosystems - in all their complexity - will perish. It jars the mind: unique, delicate, and entirely dependent on that vent. Are we the same? If the cheap energy goes, can we hope for anything at all like the kind of life we live now? Anyone egging that future on with gay abandon might want to note what life expectancy was before the turn of the 20th century. (I'd have twelve years to go if I hit the average bang on. Christ.) OK, better question: which aspects of our lives are resilient to an energy famine, which parts may just die? What can we do to affect the outcome?