The life and career of Gene Kahn have tracked the growth and gawky adolescence of the organic food business perfectly. Kahn, now 59, dropped out of his graduate program in English at the University of Washington in 1972, leased some farmland near Rockport, Washington, and started figuring out how to raise food without pesticides, herbicides, or artificial fertilizers. He went on to create Cascadian Farm, one of the first organic food companies in the United States, which he and his business partners sold to General Mills in 2000. Kahn, the erstwhile hippie farmer and organic pioneer, has since become the big company's VP of sustainable development.

Today, it feels as though the organic food business has been around a long time and has had a huge impact. But the industry is actually so new that even a reliable measure of its size is elusive. The Organic Trade Association estimates that the industry sold $1 billion worth of products in 1990, and $15 billion worth last year--20% average annual growth over 15 years. But the whole business is still smaller than McDonald's, which sold $20 billion in burgers and fries in 2005.

Kahn, who splits his time between General Mills headquarters in Minnesota and a farm in Washington where he grows grain, was the perfect man to undertake an unusual thought experiment about the U.S. food supply.

Although the organic food movement is 30 years old, Americans still spend only 2% of their grocery money on organic products. At the same time, factory-style agriculture has helped make food much more affordable in the United States. In 1950, a typical family devoted 31% of household spending to food; that figure is just 13% now. So if we could wave a magic wand and make all American farming organic, what would that look like? Would we be able to feed the country? And could we afford to do it?

If you just extrapolate today's organic onto a gazillion acres, you do get an impossible dream.

No, that wouldn't work. Because that's simplistic thinking. But we're not going to be dumb about it. We're going to put the whole agricultural research infrastructure behind this thing, we're going to put public policy behind this thing. Organic has equal or increased potential to produce feed and fiber for the country, in theory. In practice today, that's laughable.

My assumption is that by waving the magic wand, we'd be doing it right. To create an organic agriculture that was the only form of agriculture in the United States--well [laughing], you'd need to deal with a number of broad areas. Where are you going to get all of the nutrients, the macro- and micronutrients to grow the food? Currently, we're using fossil fuel for most of that--to make fertilizer--but we'd need to find organic sources for a whole host of nutrients. The best, the most practical way would be to build a whole new composting infrastructure across the United States. That would require tremendous coordination across municipalities, and much more thorough composting of all human refuse. We'd have to find more practical ways of growing crops without the use of synthetic pesticides. You would need insect control, disease control, weed control--weed control is the single largest factor, the most influential, most costly.

Why is weed control so hard?