- 27 -

consume imported food is higher among urban dwellers. This appears to be the case for reasons of higher urban incomes, status, and easier and quicker time of preparation (Delgado). Urban growth due to rural-to-urban migration is influenced by government policy. Macroeconomic policies, pricing policies, and the provision of social services all contribute to shifting the ruraVurban terms of trade in favor of urban dwellers and thereby making migration from rural to urban areas more attractive. This is likely to increase food impets due to higher demand, but also there may be a supply-side effect if urban migration depletes the rural labor force leading to a decline in domestic production.

Agerereate pattern of food imports. The aggregate patterns of Africa's food imports are presented in figure 9. Food imports varied little between 1970 and 1976, ranging between 7-8 million metric tons. Over the next four years, however, food imports doubled to more than 14 million tons, and remained at these high levels until 1986 when they began to fall gradually. Surprisingly, the period during which this sharp increase occurred was a very favorable period in terms of the weather pattern and its effect on cereal yields (except in 1979). And food aid accounts for less than 10 percent of the increase, although food aid shipments continued to grow in the 1980s raising its share in the total considerably, especially following the 1982 and 1983 droughts (imports net of food aid fell to under 10 million tons by the mid-1980s).

On closer examination of these data, however, one notes that the doubling of Africa's food imports during this period resulted in large part from events in one country, Nigeria (figure 9). Indeed, seventy percent of the increase in Africa's food imports -- or about 5 million tons - is accounted for by changes in Nigeria's imports during that country's oil boom. Given the events in Nigeria during that period, a number of contributing factors suggest themselves. First, oil revenues resulted in a sharp rise in the nation's income and capacity to import. Annual import capacity, defined as export earnings, net borrowing, direct foreign investment, and aid, nearly doubled, increasing by $14 billion during the same period (figure 10). Second, the disruptive economic impact and "dutch disease" effects of the oil boom on macroeconomic variables resulted in rising prices and wages, an increasingly overvalued currency, a shift of labor from traditional agriculture to industrial and service sectors, and rural-to-urban migration. All of these factors contributed to both rising demand for food imports and a decline in domestic production relative to population.

The changes which were brought about were of such magnitude that for three of Nigeria's four major agricultural exports -- peanuts, cotton, and palm oil -- exports ceased, and in all three cases Nigeria became a net importer of these commodities by the 1980s.

These very dramatic changes that occurred in Nigeria -- Africa's largest economy -- are likely to be indicative of phenomenon at work in other countries, albeit to a lesser degree. How generalizable these phenomenon are in explaining Africa's food crisis, is the question to which we now turn.

Empirical mode. To test the significance and relative importance of these variables in explaining changes in Africa's food imports an econometric model is estimated for a sample of 31 countries with data from 1971 to 1987. For a sample with these characteristics, pooled cross-section, timeseries analysis was chosed as potentially the most powerful method. Food imports are regressed on