The productivity of American workers in the non-farm sector of the economy rose 0.5 percent in the first three months of 1989, up 0.2 percent from the first quarter of 1988, the government reported.

The Labor Department said Wednesday that output in the non-farm sector rose 3.6 percent during the first quarter while hours worked increased by 3.1 percent.Significant productivity gains were reported in the manufacturing sector after a sluggish fourth quarter.

The department reported productivity in manufacturing rose at a 3.8 percent seasonally adjusted annual rate in the first quarter, with output rising a substantial 4.6 percent while hours of all persons working increased just 0.8 percent.

That compared to a revised productivity gain of 1.6 percent in manufacturing in the fourth quarter of 1988 and was an improvement over the 3.2 percent gain reported in the first quarter a year ago.

In the non-farm sector as a whole, the Labor Department reported that unit labor costs rose 5.2 percent in the first quarter, up from 4.1 percent in the previous three months.

In the manufacturing sector, hourly compensation increased by 4.1 percent but, in a sign that wage gains made by American workers are lagging behind inflation, the department said real hourly compensation for the sector dropped 1.2 percent when the increase in consumer prices was taken into account.

In the overall business sector - which takes farming into account - productivity rose 3.5 percent in the first quarter, a figure heavily influenced by the rebound from last year's drought. Productivity had declined 1.0 percent in the overall business sector in the final quarter of 1988.

Wednesday's productivity report contained a number of revisions of previously reported data for 1988.

As revised, the department said non-farm business productivity rose 1.5 percent for all of 1988, with output growing by a revised 5.2 percent while hours worked increased by 3.7 percent. Also reported was a revised increase in unit labor costs for the year of 3.1 percent.