The omnibus spending bill signed into law by President Reagan on Dec. 19 included a new annual federal grant of as much as $5 million to be divided among nine Washington arts and cultural organizations, including the National Symphony, Corcoran Gallery, Shakespeare Theater at the Folger and Arena Stage.

The so-called National Capital Arts and Cultural Affairs Fund was tucked into the spending measure in what one beneficiary this week said was an "11th-hour agreement." The new fund was engineered by two key members of the conference committee drafting the omnibus bill: Rep. Sidney R. Yates (D-Ill.), chairman of the House Appropriations interior subcommittee, and his counterpart in the Senate, Sen. James A. McClure (R-Idaho).

The fund was established, one source said, because McClure "was tired of being lobbied" by Washington arts organizations, who would pressure him in recent years after Yates had approved funds for the organizations in the House. Yates and McClure were unavailable yesterday for comment.

The Capital Arts Fund was only one of many similar special interest provisions, sometimes referred to as Christmas-tree ornaments, hung on the huge spending bill by influential House and Senate members. Pet legislative projects range from new university grants to overturning a U.S. Parole Commission ruling to increasing aid money for Tunisia.

Sen. Alfonse M. D'Amato (R-N.Y.), for example, got $11.1 million earmarked from Defense Nuclear Agency funds for a program to train microelectronics engineers at the Rochester Institute of Technology in New York. The institute needed the money in order to retain $7 million pledged by private sources, according to congressional records.

In early 1985, D'Amato, a member of the Senate Appropriations defense subcommittee, tried unsuccessfully to get the money from a Commerce Department appropriations measure, according to one of his aides.

D'Amato justified the subsequent diversion of defense funds to the microeletronic center as necessary to "address a critical national need by providing the U.S. electronics industry and the Department of Defense with increased numbers of high-tech engineers."

D'Amato also pulled out $12 million earmarked for the Defense Advanced Research Projects Agency to help complete a computer center at Syracuse University in New York -- despite a lack of Pentagon support and objections from other senators and competing universities about turning scientific grants into "pork barrel" projects.

The Syracuse facility, which would house the university's computer research programs, already had received $13 million in the past two years from other contributors including federal, state and local sources. Sen. Ted Stevens (R-Alaska), chairman of the Senate Appropriations defense subcommittee, defended the Syracuse grant as "a project that will be of substantial benefit to the nation."

The Capital Arts Fund starts with $2 million beginning June 1. To tide the groups over for the next six months, specific allocations of $175,000 were made from various Interior Department agencies for the National Symphony, Washington Opera Society, Phillips Gallery, Corcoran Gallery, Arena Stage, National Building Museum, National Capital Children's Museum, Ford's Theater and Shakespeare Theater at the Folger.

Last year, Yates gave many of the Washington organizations as much as $340,000, and all were expecting at least that amount this year, sources said.

McClure initially wanted them to compete for the money but the groups got together and worked out a formula to divide up any fund approved by Congress, a participant said. The measure provides a maximum $5 million funding for any calendar year.

The measure also opens the way for other Washington-based organizations to share the pie. But it requires them to be nonprofit and nonacademic with "demonstrated national repute" and operate an annual budget of at least $1 million for three consecutive years. One participant in the program said he could not think of another group that would qualify.

In another provision of the omnibus bill, Sen. Frank R. Lautenberg (D-N.J.), with the help of several colleagues, persuaded Congress to suspend an unpublicized U.S. Parole Commission proposal. Lautenberg said the proposal would have been "soft" on individuals convicted of using inside knowledge to make money on stock trading, the so-called "insider trading" offenses. A commission lawyer said yesterday that because of the legislation, "we will seriously consider some other approach."

The commission had established an interim rule permitting almost immediate parole for anyone convicted of insider trading that involved less than $1 million; convictions involving larger sums could be followed by parole in 12 to 18 months. The rule was triggered by the four-year sentence given former deputy defense secretary Paul Thayer for insider trading.

Lautenberg pushed the Senate to approve an amendment barring the parole commission from adopting the rule for six months. He said the rule "lets insider traders walk, while those convicted of other securities frauds and comparable white collar crimes remain in prison." The House-Senate conferees adopted the measure after first adding language they said would not affect the Thayer case -- his four-year sentence was reduced by the commission to 19 months -- and others already in the system.

In another example, Senate Minority Leader Robert C. Byrd (D-W.Va.) led a coalition of coal state legislators to get $400 million switched from the synthetic fuels program to a "clean coal" technology program, which will be matched with an equal amount of private funds. The program is intended to demonstrate technologies for more efficient coal use and emissions control.

The conferees agreed to earmark another $350 million to the new program from the dismantling of the Synthetic Fuels Corp., but the Reagan administration has yet to sign off on that commitment.

The foreign aid portion of the funding bill traditionally has been subjected to legislators' individual notions of foreign policy.

Rep. Silvio O. Conte (R-Mass.) made certain that $40 million in military assistance funds and $27 million in foreign military sales credits were earmarked for Tunisia. According to a House aide, Conte wanted to reward that country for refusing to admit the hijackers of the Achille Lauro cruise ship.

Rep. Jerry Lewis (R-Calif.) held up $5 million in economic support for the Marxist regime in Mozambique "until a democratic election has been held."