Nigeria is starting over again. The present is bleak, but the future is promising.

Despite substantial oil exports, twice the land area of France and a cadre of educated workers, Nigeria is broke and its people survive on some of the world's lowest incomes.However, Nigeria just elected President Olusegun Obasanjo. He ruled the country fairly well as a general in the 1970s, and then peacefully handed over the country to an elected government.

Obasanjo's election is a big step in the right direction for Nigeria, which suffered under the most corrupt ruler in its history, Gen. Sani Abacha, who died under mysterious circumstances a year ago.

In the days of high oil prices, Nigeria was a major importer of farm products, buying several million tons of wheat and foodstuffs every year. Every man who was able to leave farming did so, going to work in the oil industry.

When oil prices crashed in 1983, the government banned food imports to conserve foreign exchange. But if Nigeria can stay on a constructive economic course, it is likely to become a major food importer again while strengthening its own agricultural base.

Lately, the Nigerian market for foodstuffs has been dismal. The city folk, who bought bread made from imported wheat in the 1970s, couldn't even afford white cornmeal in the 1990s. By necessity, cheap root crops such as cassava and yams have been the diet staples for the average Nigerian consumer.

Yet Nigeria has a great deal of agricultural land, and more than one-third of its people farm for a living. At the moment, most are locked into low-productivity farming systems, such as collecting cocoa from half-wild trees in the forest or cultivating poor-yielding varieties of oil palm. In the recent past, the government let notoriously greedy marketing boards monopolize cocoa and palm-oil sales, so growers had little incentive or resources to plant high-yield varieties or protect them with pesticides.

Few Nigerian farmers can afford fertilizer. The irony is that the country flares off more than 20 million cubic meters of natural gas each year from its major oil fields, gas that could be turned into nitrogen fertilizer.

Past governments mandated such low domestic prices for gas and fertilizer that companies simply didn't invest the capital to supply potential Nigerian customers. If the government price controls and corruption are ended, Nigeria could offer cost-effective supplies of fertilizer at least to its own farmers, and perhaps to those in neighboring countries as well.

Nigerian agriculture should also benefit greatly from new research at the International Institute for Tropical Agriculture, which is delivering improved varieties of corn, rice and cassava. The institute has also introduced the soybean and soy foods to help overcome a severe protein shortage now typical of Nigerian villages. For the future, there's no question that Nigeria has the farming potential to supply far more food than it does today. However, Nigeria's farmers will not be able to meet the demand for improved diets if its economy begins to grow rapidly.

Nigeria's population is likely to reach nearly 250 million by 2020, making it almost as populous a market as the United States. If all goes well, an affluent Nigeria in 2020 would feed its cassava and yams to hogs and goats, while its people moved up to bread, rice and resource-costly foods like meat, fruit and dairy products. Cotton consumption would soar.

New urban jobs will develop first in coastal cities like Lagos, the capital, that has some 6.5 million people, and the oil center of Port Harcourt. At the beginning, it will be cheaper to supply those cities with imported food from ships than from inland farms over Nigeria's thin and decrepit network of roads and rails. Only as the Nigerian transport system gradually reaches out from successful cities will its farmers be able to buy inputs and transport their crops at low cost.

Many of Nigeria's farmers will also find that they can make more money from ''industrial'' crops like cotton and palm oil than from corn or soybeans. Many others will find employment in the burgeoning meat industries (primarily poultry) to meet the protein demands of the populace.

Agricultural imports will always be important. Nigeria has never been able to grow any significant amount of wheat, even in its northern highlands. In fact, it is already back to being one of the world's major wheat importers, buying 1.5 million tons this year, mostly high-quality hard red winter wheat.

The world can hope that Nigeria is now putting its feet firmly on the ladder of economic success and that both its farmers and city residents will see their incomes rise strongly in the decades ahead.