KENYA

Soon after his 19th birthday, Moses Kabui quit the family land here and set out for the city lights of Nairobi. That was shortly after independence in 1963, and Mr. Kabui found the town filled with young people like himself who had some farming skills, a little education, high hopes, but almost no chance of winning white-collar jobs.

It was a miserable time, he remembered: ''The best work I could get was pushing a fruit barrow, and because I had no family in Nairobi I had to find a place to sleep. I couldn't save enough for the things I wanted and I felt my youth was wasting away.'' At the age of 22, Mr. Kabui decided to go home and work the land left to him by his parents.

His inheritance was three acres of couch grass on a 70-degree slope. He married a local girl, planted some bananas, maize, and beans, and then with the help of his father-in-law decided to try his hand at coffee-growing.

Between 1975 and 1979 the Kabuis used a shovel and hoe to cut more than a mile of terracing across the hill. Between food crops they planted almost 1,000 coffee trees. In 1981 they harvested 6,600 pounds of coffee beans and a cash return of 12,000 shillings ($952).

With the maturing of the trees last year the family picked 11,000 pounds - worth almost $1,600 - and became something of an exception in a nation where the average per capita income is only $200 a year.

Unfortunately for the government, the average Kenyan seems to believe the only way to improve his or her standard of living is to move to a town or city. The population of Nairobi is growing at an unmanageable 5 percent per year; 50 percent of the people are under age 15, and only one-half of the population is literate.

With a national population growth of 4 percent - the world's fastest rate - and a land mass that is 80 percent arid or semiarid, the country is in danger of losing its self-sufficiency in food.

''We are trying to tell people that there is honor in manual labor,'' says Agriculture Minister F.L. Munyua Waiyaki. ''We would like the people to stay on the land.''

Dr. Waiyaki said that with better health care and living standards the population grew from about 11 million at the beginning of the '70s to more than 17 million last year. Although the government invested in family planning through education and health clinics, Kenyan attitudes would not change overnight, he emphasized.

He said couples were under social pressure to name one child after each grandparent, and there had been a tendency after independence to see the family planning idea as a conspiracy of the industrial nations.

''People pointed to much smaller countries like Britain and France, which had much larger populations, and then to Kenya with 600 thousand square kilometers, and said, 'We have plenty of room,' '' he said.

''It's true that we have the land, but most of it is arid or semiarid and people don't want to live in those areas. Eighty percent of the people are living on about 20 percent of the land.''

Dr. Waiyaki says the government is trying to turn the tide of young people to the cities by relocating industries and job opportunities and by providing rural areas with better access to schools, medical care, and recreational facilities.

He says the textile industry has been shifted from Nairobi to Thika and Mombasa. Food processors, he added, are being lured to more logical bases in the producing areas by government promises of electrification and water services.

The government is allocating 38 percent of its gross national product to agricultural development. The restoration of marginal lands and water catchments , together with incentives for more effective dry-land farming practices, has become the nation's No. 1 priority.