South Africa is about to end a significant era and begin a new one that seems to promise more progress toward racial justice.

After 11 turbulent years in power, P.W. Botha announced this week that, in effect, he will retire in a couple of months and give way to a new president, probably Education Minister F.W. de Klerk, who earlier succeeded Botha as leader of the National Party.To his credit, Botha removed numerous discriminatory laws and instituted a reform program to bring blacks into politics at the local level. He also introduced the three-chamber parliament that brought mixed-race South Africans and Indians into national politics for the first time.

But Botha fell short of accommodating black aspirations for equality, leading to widespread rioting that after two years forced the government to impose a nationwide state of emergency that remains in effect. In response, the international community started imposing economic sanctions against South Africa.

If de Klerk takes over, he is expected to be more willing than Botha was to initiate negotiations with major black leaders.

There are, however, limits to how far and fast the next president of South Africa can go without risking a sharp - and possibly violent - backlash from conservative whites who consider even Botha's reforms excessive. Likewise, there are limits to how swiftly the outside world can reasonably expect South Africa to evolve toward black rule until there is a reasonably large cadre of blacks trained to take over not just top leadership positions but also those in the lower ranks of the bureaucracy.

After the new regime takes over from Botha, the United States ought to consider lifting the economic sanctions it has imposed on South Africa. Such sanctions often hurt the very people they are supposed to help. Besides, when it comes to encouraging progress, the carrot can be more effective than the stick.