A severe drought in much of the Southern Hemisphere, which has scorched corn and wheat fields in food-exporting countries as far apart as South Africa and Australia, enhances North America's role as the breadbasket of the world.
The drought, the worst in living memory in Australia and southern Africa, will halve Australia's wheat crop and slash South Africa's corn production by two-thirds.
The Food and Agriculture Organization (FAO) says that 10 countries in southern Africa face severe shortages or a poor crop outlook. Botswana has been forced to declare a state of emergency.
At the same time, concern about the devastating drought is mitigated because the food position in North America is so strong right now, world food experts say.
''Happily North America is rolling in surplus right now, so there will be no problem in pulling up the slack of this magnitude,'' says John W. Mellor, director of the International Food Policy Research Institute in Washington, D.C.
It is precisely because the US agricultural larder is so well stocked that the Reagan administration is moving to reduce by as much as 36 percent the number of acres given to the growing of grains this year. The Reagan program would leave unplanted 82.3 million acres of land on which American farmers would normally sow grains and cotton.
The fact that the US is cutting back on its food stocks at a time when international pressures for more food are growing leaves some world food experts uneasy about possible future global scarcities. But a spokesman for the FAO sees no crisis ahead. ''This unplanted acreage is land in the bank. It can be put back into use when the need arises,'' he says.
While North America may well be able to come to the rescue of the Southern Hemisphere, the drought leaves unresolved a number of economic and political issues:
1. Australia, rich in wheat, sheep, and fruit, has been reeling from the effect of drought and fires. One estimate puts the total cost of the drought to Australia at $7.5 billion. Although good rains have fallen recently, it is anticipated that Australia's wheat harvest will be cut in half this year.
Australia was the world's fourth-largest wheat exporter until this year, but it will almost certainly lose its ranking to Argentina, which is enjoying a bumper wheat crop. On the whole, South America has been spared the drought that has afflicted much of the rest of the Southern Hemisphere.
An Australian official insists that there are no indications as yet that Australia will not be able to fulfill its existing grain contracts. But Australia has lost so many head of sheep and cattle through both drought and bush fires that its meat exports may be affected for years to come. In 1975, Australia had 33.4 million head of cattle. At the latest count, it was down to 22.8 million.
2. South Africa, the agricultural powerhouse of Africa, has to some extent been able to neutralize its negative political image in black Africa by using its agricultural muscle.
Normally South Africa produces some 30 percent of Africa's maize (corn) - enough to feed not only its own population of 26 million people but also half a dozen black African states and other markets. This year, because of drought, South Africa's corn production was slashed from 12 million tons to 4 million tons. One result was an announcement yesterday that the republic is canceling delivery of 760,000 metric tons of corn to Taiwan.
Not only will South Africa have no corn at all to export this year but the situation is so serious that it will have to import 2 million tons of corn, according to South African officials.
The drought threatens the position of South Africa and Australia in an exclusive club in the world - the half dozen nations that are largely net exporters of food. The US, Canada, Argentina, and Thailand are the other ''members.''
3. For black Africa, which is still suffering from the effects of protracted droughts in the Sahel region and in the Horn of Africa, the latest drought in southern Africa could not have come at a worse time. Africa's agriculture is deteriorating so rapidly that the World Food Council, an agency of the United Nations, says Africa has 10 percent less food than it did in the mid-1960s. And the council forecasts a continuing slump in food production throughout the 1980 s.
African states, in recognition of this dire prospect, are trying to correct the situation by placing a high priority on agriculture. But the results so far have not been encouraging.
Zimbabwe, one of the agricultural hopes of Africa and one of the few African countries that has been self-sufficient in food, should have been a sizable food exporter this year. But the FAO's early warning system, which monitors climatic conditions and alerts the international community, indicates that Zimbabwe ''is also in a mess'' because of the drought.
Zambia, which had hoped to break a six-year dependency on imported food, will fall some 400,000 tons short of having enough corn to meet the nation's needs.
Mozambique is worse off. Even beyond existing stocks, food aid, and regular commercial imports, this country is expected to have a cereal deficit this year of 345,000 tons.
4. Although the United States is in a strong position to bail out the developing countries, the short-term assistance will not resolve Africa's long-term agricultural problems, an agricultural expert warns. Moreover, the ability of American markets to meet the food challenge far exceeds the capacity of third-world countries to pay for the food.
As a source familiar with how Washington operates put it: ''When there is a crisis on the scale of the Sahel, Congress responds. But at the moment there is no urgency in Washington about the drought situation, and any food aid will have to come out of foreign assistance.''
The implication was that what was taken out of foreign aid to meet Africa's food needs will mean a cut in other budget allocations at a time when foreign aid is hard to come by.