Virginia's unemployment rate fell slightly to 8 percent in March, mainly because of a weak seasonal pickup in construction, agriculture and various service industries, the Virginia Employment Commission reported today.

The revised jobless rate for February was 8.1 percent. The preliminary February figure was reported at 8.4 percent, but that was revised downward when more recent figures became available, said William F. Mezger, assistant manager of the VEC's office of research and analysis.

There were 211,100 Virginians out of work in March compared to 212,900 in February, said Mezger. The VEC said the 1,800-person reduction in the ranks of the jobless was due mainly to limited recoveries in farming and construction.

"This March's seasonal dip in unemployment was, however, several thousand below normal as the spring back-to-work movement was slow getting under way," the employment commission said.

Virginia manufacturers continued to cut their payrolls in March, the VEC said, with the biggest job losses coming in the textile, furniture and transportation equipment industries.

Northern Virginia's unemployment rate of 4.6 percent remained the lowest of all the state's urban areas.

The jobless rate in Richmond rose to 5.9 percent from 5.8 percent, the only urban area of the state to record an increase. The figure for the Norfolk-Virginia Beach-Portsmouth area dropped from 7.5 percent to 7.4 percent, while unemployment fell from 7.4 percent to 7.3 percent in Newport News-Hampton.

The largest declines were reported in Roanoke, where the figure fell from 8.2 percent to 7.6 percent, and the Petersburg-Colonial Heights-Hopewell area, where it dropped from 10.7 percent to 10.1 percent.

The VEC said the normal pattern is for some further seasonal reductions in unemployment in April as other activities move into full swing.