BANANA HILL, Kenya Stephen Waithaka, who farms less than a hectare of the rich volcanic soil on the foothills below Mount Kenya, brings in two crops of corn a year, but lives in constant fear of not having enough.
"In the last five seasons we did not sell anything, because we did not have rain," Mr. Waithaka said of a crop that drought has reduced by half. "We still had enough for ourselves. I fear others did not."
The fear is well-founded. A comprehensive study of whether the world will have enough to eat 20 years from now concludes that Africa, at least, probably will not.
The report by the International Food Policy Research Institute in Washington predicts rising hunger on the continent, which is notorious for periodic famines and struggles to feed itself even in normal times. The study concludes that without enormous investment in irrigation, roads to take the harvest to market and crop research, Africa might have 49 million malnourished children by 2020, a rise of 50 percent.
At the same time, the rest of the world, including India and China, will be better nourished than it is today, the report predicts.
African experts on agriculture - a sector widely neglected by African governments even though three-quarters of Africans are farmers - consider that prediction credible.
"They are really seeing things as they are," said Mercy Karanja, chief executive of the Kenya National Farmers' Union, referring to the report released last week.
"We're talking budgetary allocations in Kenya of 4 percent for agriculture, of which 3 percent is supporting the parastatals state-owned enterprises," Mrs. Karanja said. "It is such an insult to farmers. This does not show even understanding."
Finding enough to eat is a daily challenge for the vast majority of Africa's nearly 700 million people. Most Africans rely on homestead plots of two-fifths to four-fifths of a hectare (one to two acres) for survival.
They cultivate staples such as corn or cassava, eat what they need and stack any surplus for sale on a plastic sheet at the local market. The pennies from those sales may be the only cash the household sees. It will buy the used clothing that most Africans wear, or perhaps a handful of tomatoes from the next plastic sheet in the market. Meat is a rare treat.
"What do you do? If you can't buy the food, you have to raise it yourself," said Mr. Waithaka, 48. His family of seven has survived off four-fifths of a hectare on Banana Hill, a nominally residential township outside Nairobi, since his job as an insurance surveyor dried up with the Kenyan economy five years ago.
Far more than the wars that dominate headlines, this precarious hand-to-mouth existence defines life on the continent two generations after most of its countries gained independence from European colonial masters.
Ambitions declared in the flush of nationalism - industrialization by the year 2020, in the case of Kenya - have gone the way of broken telephone systems, cratered roads and health centers better stocked with mildew than medicines.
Hunger binds the continent as it binds the stomach. In Sudan, where a history of war-related famine prompted the United Nations to establish a permanent food airlift, a Dinka tribeswoman hands back a snapshot of a relief worker's daughter with the words: "She is beautiful. She is not hungry."
Sixteen hundred kilometers to the south, in peaceful Malawi, a political party's slogan, "Get the grain, not the husks," is no metaphor. In cooking pots outside residents' mud huts, a rolling boil softens a dinner of chaff.
The report, based on a computer model taking into account population, prices and production data for 16 commodities, delivers a mixed message. Worldwide, rising outputs and declining prices mean that the global market's growing demand for cereals was generally met over the past two decades. In the process, the global rate of malnutrition among children under 5 dropped from 45 percent in the 1960s to 31 percent today.
But in Africa, many people are simply too poor to participate in the global market. Population gains outpaced cereal production on the continent between 1967 and 1997, and countries lacked the hard currency to purchase imports that would have filled the gap.
As a result, a third of African children suffer from hunger. The institute said that by 2020 that number will likely reach 39 percent to 49 percent, depending on whether conditions remain the same as today or grow worse. The report acknowledges that given Africa's troubling trends in governance, the pessimistic forecast is more likely.
"To really get the purchasing power to buy food, you have to produce more food," said Mark Rosegrant, the primary author of the report, called 2020 Global Food Outlook.
The key, Mr. Rosegrant said, appears to be larger yields. A single hectare in Europe produces six times the cereal harvested from a hectare in Africa, on average. Few African farmers use fertilizer or irrigate their fields. They live at the mercy of the weather, which in East Africa has been especially unpredictable since the 1997 floods caused by El Nino.
"This is the biggest problem we have here in agriculture - the water," said Mr. Waithaka, one of the few farmers on Banana Hill to have built a concrete reservoir.
Another challenge is transport, Mr. Rosegrant said. In its search for arable land, Africa's rural population has moved even farther from the increasingly rare usable roads. And if there is no access to markets, gains in production stand to be wasted. AFRICA would stand to gain more than any other region by full liberalization of trade laws, Mr. Rosegrant said, not least because it would remove domestic taxes on production and consumption that discourage farmers from investing. In all, African governments will need to invest $133 billion over the next 20 years to avoid the predicted sharp rise in malnutrition, the report says.
Some experts say the money should go toward research aimed at developing crops that will thrive in African soils, roads, irrigation, education and clean water.
These recommendations assume that Africa's often dysfunctional governments will pay attention. To date, Mr. Rosegrant said, only a handful, including Uganda, Botswana, Ghana and Mozambique, share their citizens' preoccupation with feeding themselves.