The busing plan approved by the Prince George's County citizens advisory committee earlier this week would modify present busing patterns to make it possible for approximately 3,600 elementary school students to attend schools nearer their homes.

The plan tinkers with present busing routes by eliminating almost all busing that has no affect on racial precentages in schools. Seventy percent of affected students are black and 77 schools are involved.

Under the proposal, which must now win approval from the county school board, about 1,400 of the students would be able to walk to school. The remainder would be transferred to schools closer to their homes and a shorter bus ride away.

The advisory committee's proposal eliminates cross-busing -- the busing of black children to predominately black shools in other parts of the county and the busing of children out of integrated neighborhoods to schools in other integrated neighborhoods miles away.

School board staff members said the cross-busing is a result of changing residential patterns in the county.They note that since 1972, when the original court-ordered busing plan went into effect, the county's black population has grown steadily and many formerly all-white or integrated neighborhoods now have substantial black populations.

In the meantime, the black student population has increased from 25 percent of the total elementary school enrollment in 1973 to 47 percent in 1979.

Because of the demographic changes, the present busing plan has led to what advisory committee members labeled "unnecessary busing." To eliminate such busing, the committee first considered a neighborhood school assignment system. It dropped the idea after a school board study showed that the number of one-race schools would increase dramatically if all students attended their neighborhood schools.

The committee also considered a modified neighborhood school assignment system which would require that black students make up between 20 and 80 percent of the enrollment of all schools. The school board refused to allow its staff to prepare such a plan because board members feared they could be tied to racial quotas.

Although the plan finally adopted reduces busing, it affects the racial makeup of the schools only marginally, neither adding to nor taking away from the trend toward resegregation that has occurred in the school system in the past eight years. Under the plan, the black populations of most schools change from 5 to 7 percent and the number of schools with black enrollment under 20 percent and over 80 percent remains stable. At present, there are 29 such schools. Under the advisory committee plan, there would be 31.