If Nothing Else, Save Farming According to farm scientists at Cornell University, cultivating one hectare of maize in the United States requires 40 litres of petrol and 75 litres of diesel(3). The amazing productivity of modern farm labour has been purchased at the cost of a dependency on oil. Unless farmers can change the way it’s grown, a permanent oil shock would price food out of the mouths of many of the world’s people. Any responsible government would be asking urgent questions about how long we have got.