Maize is grown in greater tonnage than any other cereal. The production figures show the United States first at about 378 million tonnes and China second at 295 million — each producing more than the entire global wheat output of many countries combined.
The number that explains the chart is not in it: only a modest share of this crop is eaten directly by people. The majority becomes animal feed, and a substantial further portion becomes ethanol and industrial starch.
Which is why the growth is where it is
American output rose about 87 per cent since 1990. That is strong, and it is the slowest growth in the top four.
China tripled production. Brazil grew more than fivefold, from 21 to 115 million tonnes. Argentina went from 5.4 to 57.5 million — more than tenfold.
These are not countries that suddenly started eating more corn on the cob. They are countries that built or supplied livestock industries. Brazilian and Argentine maize expansion runs alongside their soybean expansion, and for the same reason: both crops feed animals, and demand for meat rose steeply across Asia over exactly this period.
Argentina's tenfold increase is the standout. It reflects a shift to continuous cropping, wide adoption of genetically modified varieties, and — importantly — export policy that swung between taxing grain exports heavily and liberalising them. The production curve responds visibly to those decisions.
The ethanol distortion
A large share of the American crop does not feed anything. It is fermented into fuel ethanol, under a federal mandate requiring biofuel to be blended into petrol.
This makes the maize market unusual: a meaningful part of demand is set by legislation rather than by hunger or appetite. When the mandate changes, or when oil prices move enough to change the economics of blending, it affects the price of a staple grain. Several food-price analyses have argued this couples fuel markets to food markets in ways that hurt poor importing countries, and the criticism is hard to dismiss entirely.
Where maize actually is food
For a large part of sub-Saharan Africa and parts of Central America, maize is the staple — eaten as porridge, as tortillas, ground into meal. Nigeria, Ethiopia and South Africa all appear in the top fifteen, and there the crop feeds people first.
This creates an awkward asymmetry. The same commodity is a dietary staple in one set of countries and a livestock input or fuel feedstock in another, and they bid against each other in the same market. When American ethanol demand or Chinese feed demand rises, the price rises for a household in Malawi buying maize meal.
That is the thing worth taking from this ranking. It looks like a table of who farms the most. It is closer to a map of who can afford to feed grain to animals and machines rather than to people.