Where your food comes from

A plate of rice, vegetables and fish looks local, and much of it is. But the inputs behind it travel further than most people imagine, and the journey explains why food prices move for reasons that have nothing to do with farming.

Start with the rice. The seed may be a variety developed at a research institute, bred for resistance to a disease that appeared twenty years ago. The fertiliser is likely to contain potash mined in Canada or Belarus and nitrogen made in a factory that burns natural gas. When the gas price rises in Europe, fertiliser becomes more expensive in the Mekong Delta, and a farmer who has never left the province pays more.

The fish may be farmed rather than caught, and farmed fish eat feed made partly from soya and partly from smaller fish caught far away. The vegetables arrive by road, in a lorry whose diesel price is set in international markets, driven on a schedule set by a wholesaler who is guessing what the city will buy tomorrow.

This web has two faces. It makes food cheaper and more varied than any local system could, and it transfers risk efficiently: a bad harvest in one region no longer means hunger in another. It also transmits shocks quickly. A war, a port closure or a drought on another continent appears in a market here within weeks.

For students, the useful habit is to ask one more question than the obvious one. Not only what is the price of rice, but what sets the price of what grows the rice.