Corn prices in America have spiked. And since corn is also a prime ingredient for animal feeds and sweeteners, prices likewise are rising for poultry, beef and everything from soft drinks to candy.

There is currently more corn acreage - about 90 million acres are predicted this year - than at any time in the nation's last half-century. But today's total farm acreage is either static or shrinking; land for biofuels is usually taken from wheat, soybeans or cotton, ensuring those supplies grow tight as well.

In the past, the genius of our farmers and the mind-boggling innovation of American agribusiness meant that farm production periodically doubled. Indeed, today we are producing far more food on far fewer acres than ever before.

But we are nearing the limits of further efficiency - especially when such past amazing leaps in production relied on once-cheap petro-chemicals, fuels and fertilizers.

As in the case of oil, we've gone through these sudden farm price spikes before. My grandfather once told me that in some 70 years of boom-and-bust farming he only made money during World Wars I and II, and the late 1960s.

But this latest round of high food prices seems coupled to energy shortages, and so won't go away anytime soon. That raises questions critical to the very security of this nation, which may have to import as many agricultural commodities as it does energy - and find a way to pay for both.

The American consumer lifestyle took off thanks to low-cost fuel and food. Once families could drive and eat cheaply, they had plenty of disposable income for housing and consumer goods.

But if they can't do either anymore, how angry will they get as they buy less and pay more for the very staples of life?