he Maryland General Assembly, heading into the final 72 hours of a legislative session that has been relatively calm, tonight lumbered through its calendar by giving preliminary approval to child welfare legislation, killing voluntary prayer in schools, and extending the deadline for a multimillion dollar bond authorization for Baltimore's Memorial Stadium.

The tempo of activity in the State House chambers, although by no means slow, contrasted sharply with the chaotic climaxes of past legislative sessions. Unlike last year, when controversial legislation including the state budget was being debated until the final moments, the agenda here now is noticeably bland. The fates of this year's most pressing political issues--raising the drinking age, a new gasoline tax, an increase in interest rate ceilings for consumer loans, and delaying the start-up of a controversial emissions inspection program--have already been decided.

The child welfare bill would facilitate the adoption of thousands of children who now often live for years without stable families. The bill, which the Senate voted for earlier, passed by a 21-to-2 vote today in the House Judiciary Committee and is now virtually assured final approval before the 90-day General Assembly session ends on Monday.

"This is really going to help out a lot of kids," said Cheryl D. Lynch of Associated Catholic Charities, a group that has pushed for adoption and guardianship legislation for three years.

The measure, sponsored by Sen. Arthur Dorman (D-Prince George's), would allow state agencies to place foster care children for adoption without consent of their natural parents if the children have been in continuous care for two years or more.

The measure clarifies when, or whether, parents are capable of taking back their children, and eases the process of adopting children with long-missing parents. It also provides for parental counseling, and requires a court review of all children who are still in the foster care system six months after they have become legally available for adoption.

State officials estimate that 8,300 children are now living in foster care and that roughly 75 percent of them have been in the system for longer than two years.

The average foster care child is 12 years old and has lived in three foster-care homes. Of 1,400 children legally separated from their parents, only 300 were adopted last year, despite an abundance of prospective parents anxious to adopt them.

Legislators tonight approved a one-year extension of a $22 million bond authorization for the renovation of Memorial Stadium, a bothersome issue marked in recent months by a series of tense meetings between Gov. Harry Hughes and Robert Irsay, the owner of the Baltimore Colts football team. The 31-to-14 vote on the stadium was part of a political package that was approved only after the Senate consented to a bill that would allow for the placement of 131 mentally retarded citizens in community group homes. Sen. Howard A. Denis (R-Montgomery) struck the deal by launching a modest filibuster yesterday. He said tonight that it was "a stunning victory."

In other action tonight, members of the House of Delegates thwarted an attempt by some of their colleagues to revive legislation that would require a daily period of silence in public schools. Two measures involving voluntary prayer or meditation in schools, one of which was approved by the Senate, died in the House Constitutional and Administrative Law Committee last month. The futile attempts to bring the bills to the House floor tonight signaled the death of the legislation for this year.

On another controversial and complicated matter, the House, by a vote of 90 to 24, tonight killed a Senate bill that would have called for legislative study over the summer of the controversial issue known as "decoupling," the jargon used when a state varies from federal tax law. The House had already approved "decoupling," which would enable the Maryland to continue to collect huge sums of corporate taxes that can now be deducted under new federal tax law.

Also winning final approval today was Gov. Harry Hughes' plan for congressional redistricting, which passed despite opposition from some Baltimore legislators whose congressmen will now run for reelection from substantially reshaped districts. Reps. Michael D. Barnes and Steny Hoyer, Democrats from Montgomery and Prince George's counties respectively, had no objections to the new boundaries given their districts.

Earlier this week, the General Assembly passed legislation that will allow local jurisdictions to use the court fees for marriage licenses to fund domestic violence and battered spouses programs.

The Senate, with no opposition, approved a House measure that will establish a loan authority to help private colleges and universities in Maryland finance their student loan programs. The program, backed by Hughes, bears no cost for the state.