Eighty-five Prince George's County Schools now have black majorities, according to a new official fall enrollment report. The finding has prompted school board members to renew requests for major changes in attendance boundaries last drawn by a court-ordered busing plan in 1973.

The proportion of blacks in the 226 county schools has risen to 40.7 per cent from 37.1 per cent last fall and 24.9 per cent five years ago.

The federal 1973 busing order required the county to amend school boundaries to eliminate all black-majority schools and insure that no school had a black population of less than 10 per cent.

This year four of the county's elementary schools fell below this mark, including Laurel Elementary, which has only 3.5 per cent black students.

The 85 black-majority public schools this fall represent a 30 per cent increase over last fall's figure of 67.

Before the busing order was issued in January, 1973, the Prince George's school system had 46 schools with black majorities.

Officials said the increase in the number of black-majority schools since then reflects an overall decline in the county's white population, a continued increase in the number of blacks, and a continued shift from white to black particularly in areas between the District of Columbia line and the Capital Beltway.

This fall the Prince George's County school system has 82,591 white students - a decline of 8,274 or 9.1 per cent from a year ago. The decline was the largest drop for any year since 1973, the year of the busing order, when white enrollment fell by 10,932. From 1975 to 1976 white enrollment declined by 7,496 or 7.6 per cent.

"I think these figures pinpoint that we do have a major issue before us," said Susan Bienasz, member of the Prince George's County Board of Education."We have to discover if there is a way we can get children going to school closer to home and still meet desegregation guidelines."

To that end, the board requested last year that the school staff prepare a study answering those questions. That report is expected next month when the board also begins debate on school closures, another issue that involves adjusting boundaries.

Meanwhile, black enrollment rose this fall by 3,044 compared to a year ago - an increase of 5.7 per cent. Since 1972, the black enrollment increase has been relatively steady - between 2,900 and 3,700 a year.

Overall, the number of white children attending Prince George's schools has dropped by 38,981 since 1972, a decline of 32.1 per cent, while the number of black children has climbed by 16,314, or 40.4 per cent.

The total enrollment this fall is 139,302 - the smallest number since 1967.

According to the new report, the decline in white students has been greatest at schools inside the Beltway, an area that already had a substantial number of blacks before the busing order. However, white enrollments have fallen nearly everywhere else in the county as well, reflecting a decline in births - that is part of nationwide treand.

The continued climb in black enrollment reflects the continued growth of Prince George's black population, which rose by 89,000 or 86 per cent from 1970 to 1975, according to the most recent estimates issued by the Maryland Center for Health Statistics.

In 1975 the county's overall population was 28 per cent black, compared to 15 per cent black in 1970.

"The black population is younger (than whites in the county), and it's growing from families moving in from the District of Columbia," said Luther Frantz, a statistician for the health statistics center.

Frantz said heavy black migration into Prince George's started in the late 1960s, and has continued steadily.

Four years after Prince George's County executed one of the largest court-ordered busing plans for desegregation in the country, school board members are re-evaluating the desegregation program.

"I think we can lessen the number of children being bused and still fall within the guidelines," said Chester E. Whiting, a board member. "Our race relations have improved, quite obviously, and most importantly so has the quality of education. Those are the achievements. If our schools are off-balance, we should alter the boundaries."

The number of black-majority schools in the county has risen from one - Orme Elementary - immediately after the busing order, to 20 in September, 1973, and to 46 in September, 1975.

Of the 85 schools in that category this fall, 13 have a black enrollment between 70 and 80 per cent, and two have topped 80 per cent black - Dodge Park Elementary in Landover (80.2 per cent) and Owens Road Elementary in Oxon Hill (81.7 per cent).

Most of the nine members of the school board want to reduce the busing and allow more children to walk to school. But the desire is thwarted by the guidelines that no school have less than 10 or more than 50 per cent black students.

"We're not responsible for the demographic changes, the increase in the black-majority schools, but if we redraw the boundaries ourselves we become responsible," said Whiting.