Foum Gleita, Mauritania; The writer's trip through Africa was sponsored in part by the United Nations. — ''I must believe that Allah will bring back the rain. If not, I would just lie down and die.'' The speaker, Ahmedu Ali Ba, happened to be a black-skinned Moor. He is wearing a dusty and ragged desert Arab's boubou robe, his face wrapped with a howli to protect it from the burning desert sun.
But almost the same words could be voiced by half the people in Africa as 24 countries are afflicted by what is becoming the worst drought in modern times. Everywhere you go the ordinary African's remarkable spirit and endurance are the main hope.
Foum Gleita, where a new dam stores precious river water, is just south of the great sand-sea of the Sahara. Scattered about its bone-dry earth, as gray and hard as concrete under the drifting sand, are the mummified remains of starved cattle, whole herds that dropped when there was nothing more to eat. Children with swollen bellies stare from a black tent encampment. A few moth-eaten camels scratch for a bite of thorn bush. Goats take anything that is left. Roughly painted signs point to abandoned mud-hut villages.
''Even the vultures have fled,'' says Ahmedu. He describes how people have clawed through anthills, searching for kernels of grain stored by the ants.
The Rome-based Food and Agriculture Organization reports that donors from Western countries and nations of the Organization of Petroleum Exporting Countries have supplied two-thirds of the 3.2 million tons of grain the FAO says Africa needs to avert famine. But only half of what has been pledged has arrived.
Food aid to the Sahel region is still 40 percent short of the FAO target. Only a third of pledged grain has arrived. The United States has been especially late in responding, although last month Congress passed a supplementary $90 million in food aid for Africa and President Reagan has proposed a special $500 million African initiative to be spread over the next five years.
In Foum Gleita's fierce heat, blowing red dust and the sun's glare reflecting on the sand make the whole world look bright orange. This is one of the least-known parts of Africa, on the way to the Malian capital of Bamako and the caravan routes to Timbuktu. The twin-engined plane, contracted by the United Nations to bring our party of mostly European journalists into Mauritania, turned out to be the biggest plane yet to land at Foum Gleita's short dirt airstrip.
After the swimming pools and air-conditioned hotels of Dakar on the Senegalese coast, the dust storms and desolation of the Sahel come as a shock. Sahel means ''door of the desert,'' and the Moors and Toaregswho inhabit the west of its 3,000-mile sweep have survived as herdsmen by camping in tents and leading their cattle across the sands in search of new grass springing up after rains. Their herds, nearly wiped out in the great Sahelian drought of 1972-74, had been built up again this past decade.
Now once more nomadic life faces extinction. ''There are no more cattle,'' says Jean Yves Core, a French FAO expert.
''Already last June, 40 percent of Mauritania's livestock were gone. By the end of this year, cattle may be down 60 percent. The cows gave the nomads meat and milk, hides and skins. Now they have nothing to eat and drink. The nomads must settle down if their cattle are dead.''
US Ambassador to Mali Parker Borg says, ''In some places it's already the end of traditional nomadic life.'' Mr. Borg felt the land around Timbuktu had not been fit for the nomads for a decade now. Quakers working in the area are reporting a mass exodus of population.
The Sahel's plight is only part of the story. Estimates from Mozambique and from Zimbabwe's ravaged western province, Matabeleland, put deaths by starvation at 170,000, in part because insurgent guerrillas do not allow food relief to reach victims. Southern Africa's May harvest is expected to be the third poor one in a row.
The foreign aid that has arrived is an encouraging if modest start. Africa's predicament is far from hopeless, but more attention must be paid. Too many drought victims seem to feel nobody knows or cares about their predicament.
As one of the nomads across the Mauritanian border in Mali said, ''When you have a catastrophe in the West, you have newspapers and television there. Here, when we cry about the drought, there is nobody to hear but these dried up thorn-bush trees, and trees cannot speak.''