By curbing food exports, governments buy relief for consumers at the cost of lowering output Argentine farmers are among the world's most nimble and efficient. They need to be: few countries have been as badly governed as Argentina. Over the past 70 years it has often been the farmers and their exports that have rescued the economy only to see populist governments plunder the Pampas to placate their urban voters. This week Argentina's farmers have been [protesting] at what they see as a punitive rise in a tax on their exports. With world prices for wheat and soyabeans at record levels, Argentina's president, Cristina Fern