The Kenyan village of Sauri, near Lake Victoria, is lucky. As the first so-called Millennium Village, it will benefit from roughly $110 per capita in aid annually through at least 2014. That aid is intended to help with problems ranging from disease to a lack of schooling, but it is in the area of agriculture that the village has already seen the most dramatic gains. Working with local farmers, researchers have boosted yields of maize from 1.6 to 4.9 tons per hectare--or 100 bushels of edible maize for every acre cultivated.

Soil scientist Pedro Sanchez, director of tropical agriculture at the Earth Institute and co-leader of the Millennium Village Project's agricultural team, achieved these remarkable gains by investing in the health of the soil: replenishing depleted levels of nitrogen, phosphorus and potassium with fertilizers.

Over the last several decades, farmers across the continent have removed 22 kilograms of nitrogen, 2.5 kilograms of phosphorus and 15 kilograms of potassium from every cultivated hectare every year, according to Sanchez's research. "This annual loss is the equivalent of $4 billion in fertilizer," he wrote in an article in The Lancet in January of 2005. Partly as a result of this loss, roughly 180 million Africans do not get sufficient food despite spending three quarters of their income on it. Food production on a per capita basis is actually declining.

"To feed our people, we must feed the soil," noted Nigerian president Olusegun Obasanjo at the launch of an international effort to fertilize Africa's soils: the Africa Fertilizer Summit, which starts tomorrow in Abuja, Nigeria. "Agriculture is the most direct way to improve their well-being."

Nearly 500 million Africans rely on agriculture as their main or only source of income and sustenance. Yet the agricultural innovations of the past 30 years--the so-called Green Revolution that boosted grain yields in Asia by introducing better crop varieties and greater use of fertilizers--have largely passed Africa by; though adoption of crop varieties is broadly similar throughout the developing world, Asia and Latin America have seen yield increases of 70 to 90 percent, compared to only 28 percent in Africa.

The difference comes down to fertilizer, according to Sanchez and other experts. A recent study by the International Center for Soil Fertility and Agricultural Development, or IFDC, found that the average African farmer applies one fifth of the necessary amount of the various nutrients required to maintain soil fertility. "Without a green revolution, we remain in the logic of food aid, which will never provide food security," said Alpha Oumar Konar, chairman of the African Union, at the Summit launch.

And food aid is expensive. "In Malawi, we have found that it costs about $40 for a typical smallholder farmer to get good crop yields and get out of hunger," Sanchez says. "It cost $400 to feed that same family with food aid. So it's much better to invest at the front end of the food chain, starting with the soil, water and seeds, than the tail end."

It also undermines the farmers themselves. "It destroys incentives for farmers to work when food aid arrives," notes Parker Mitchell, co-CEO of Canada's Engineers Without Borders, an organization working to improve agricultural practices in African countries, among other efforts. "The prices of all of the successful farmers' products go down."

But fertilizer does not come cheaply. Because rural Africa lacks infrastructure and fertilizers can be bulky, they can cost up to six times the price they command in the developed world. In fact, it costs more to transport fertilizers 100 kilometers inland from a port anywhere in sub-Saharan Africa than it does to ship them to that same port from North America. "You need fertilizer to be distributed to the farmer at a price where it is profitable," notes Sarah Gavian, a senior research fellow at the International Food Policy Research Institute (IFPRI). "The reason that the price is lower in America is because we have subsidized the roads and not the fertilizer."

Subsidizing fertilizers for African farmers has been tried before, of course, with some success--until the subsidies are taken away. And such subsidies have proven an efficient engine of corruption in the past. "Subsidies work more for powerful people than poor people," explains Ephraim Nkonya, another research fellow at IFPRI. "If you subsidize in one country and in another you don't, there's a big chance that it will be reexported."

"Subsidized fertilizers failed miserably. Procurement was done by governments and it was diverted to cronies, very little of that fertilizer reached the farmers," the Earth Institute's Sanchez adds. "The government should not be involved in distribution."

Sanchez and others prefer to rely on an existing network of small-scale merchants, either itinerant or fixed, already present in rural areas. "If one can show that they can make money dealing fertilizer, then the Coca-Cola dealer who is already there will sell it. The private sector dealers are there provided they see a way to get a profit out of it," says Amit Roy, president and CEO of IFDC. "The availability of fertilizer at the right time is as important if not more important than the price itself."

The availability of fertilizer at the right time--that is, before the rains but not too far in advance, points to another major issue: water. Most African agriculture relies on fickle rainstorms to ensure healthy crops rather than controlling moisture like farmers in much of the rest of the world. "There are dangers in using fertilizers with an unreliable rainfall because you can burn the crop," notes Robert Chambers, a research associate at the Institute of Development Studies at the University of Sussex in the U.K. And just as fertile soil washes to the sea as a result of land clearing--one environmental problem a green revolution in Africa aims to remedy--fertilizers are just as likely to wash away if applied injudiciously.

African farmers also labor under a different set of impediments than green revolutionaries in Asia do. Whereas those Asian farmers benefited from largely closed markets in their home countries, any surplus produced by African agriculture will compete in world markets. "In Asia, the whole paradigm was self-sufficiency," Roy says. "In Africa, it's market driven."

Peter Hazell, a professor at Imperial College London's Centre for Environmental Policy sums it up this way: governments throughout Asia invested heavily in irrigation, roads, power and agricultural research and development. They also provided fertilizer, seed and credit subsidies as well as ensuring profitable and, importantly, stable prices. Although those kinds of subsidies have proven difficult to phase out in Asia and throughout the world as the need for them has declined, they were key to boosting yields initially.

African leaders have pledged their support, vowing to allocate at least 10 percent of public budgets to agriculture in coming years. "That is an important figure," says Ian Scoones, a professorial fellow at ISD. "Whether it will be realized or not is a big question." And the Africa Fertilizer Summit begins tomorrow in Abuja, Nigeria. But extension programs that train farmers have been gutted over the past decade or so--in part due to World Bank mandates--and there may not be enough money to rebuild them. "These countries are in financial crisis. The extension systems have been de-funded. There's no one to carry out these techniques," IFPRI's Gavian notes. "If you were going to carry this out, you would need to rebuild the extension services."

"Who is supposed to bear the cost of that subsidy?" she asks. "And will they? And when they refuse to any longer, where are you if you haven't done other kinds of transformation as well?"

Some of that transformation begins far from Africa's impoverished soils. "What we've got to have is a revolution in subsidies in the U.S., Europe and Canada," ISD's Chambers says. "We're always directing our attention at them. It's our agricultural system that's a big part of the problem."

To talk about a single green revolution for all of Africa is absurd. Conditions, suitable crops, rainfall, agricultural techniques vary widely from country to country, region to region, even village to village. The irrigated wheat fields of the zamindars in the Punjab shared much more in common with their rice farming brethren in China, Japan and Taiwan than farmers in northern and southern Ghana do. A village by village approach, adopting what sprouts in the farmers' fields and minds, may be the only feasible way to improve the health of the soil, boost yields, and better the lives of residents.

In addition to Sauri, the Millennium Villages Project has set its sights on 11 more villages across Africa, from Koraro, Ethiopia, in the northeast, to Mwandama, Malawi, in the southeast, and Potou, Senegal, in the northwest. The soil conditions in each village will dictate the exact techniques employed to restore them.

For example, in Sauri the villagers have been encouraged to plant nitrogen-fixing trees--Glyricidia sepium--in fallow years to more naturally restore the soil's health. The wisdom of planting such trees sometimes eludes the villagers, according to Cheryl Palm, the other co-leader of the project. But the trees can provide scarce firewood and, if the method proves fruitful, could inspire farmers in surrounding areas to adopt the holistic technique.

But even a dozen Millennium Villages with strong financial support will not be enough. Maybe 60,000 would, according to the project organizers. From that fertile base enough ideas might spread to truly green the continent.