OK, a number of people asked me about that number. It is a very interesting rough estimate of global food production that does not include stockpiles.

It works like this. The authors of the paper take the reports of everything produced in a year, subtract everything that gets used, whatever is leftover is "the cushion" between what we produce and what we need.

In 1999 it was 150+ days.

Then Bush II sunk a big pile of money in ethanol production and ADM started selling their corn to the fed to make biofuel. The result.

By 2006 the cushion shrank to 50+ days and food riots started happening across the Middle East.

Now the cushion is down to 10+ days.

However, some countries have very deep reserves. The US and China being the biggest two. The rest of the world operates on a Just in Time basis much more than we do.