But there is more at stake than simply the ability of Haitian soil to feed a starving nation. Food-importing nations around the world also are suffering as the prices of staples skyrocket, raising critical questions about the goals of agricultural-assistance programs that over the past few decades have focused more on reducing tariffs and growing crops for export than on helping poor nations feed themselves.

That's as it should be, officials say. "Food self-sufficiency is not necessarily the goal," says Beth Cypser, deputy director of the U.S. Agency for International Development mission in Haiti. "Right now there is food in Haiti. It's just the price is out of reach. If it makes sense economically for them to sell mangoes and import rice, then that's what they should do."

The problem, says ecologist and activist Sasha Kramer, is that these days Haitian farmers can't sell enough mangoes to afford imported rice. To boost food production, Kramer and colleagues founded Sustainable Organic Integrated Livelihoods (SOIL), a nonprofit group that builds composting toilets in rural communities to get much needed organic matter and fertility back into fields. "With the current hunger crisis, it's very clear," says Kramer, an adjunct professor at the University of Miami. "If Haitians had more local production, they would not be so vulnerable to imported food prices."

Until then Haiti remains a poignant lesson in what soil scientists have preached for years: As a nation's soil goes, so goes the nation.