Kenneth L. Adelman, director of the Arms Control and Disarmament Agency (ACDA), said yesterday that he does not think the SALT II arms agreement is "essential" or "very helpful to good arms control."

Adelman told reporters at a breakfast meeting that the Soviets "are cheating on most of the provisions" of the treaty.

His remarks were in reply to questions about what would be lost in U.S.-Soviet arms control efforts if President Reagan does not reverse his May 27 decision to discontinue U.S. observance of the SALT II limits on strategic nuclear weapons. The treaty, signed in 1979, has never been ratified by the Senate.

Adelman said it was "idle speculation" to discuss such potential losses because he did not think the Soviets would comply with SALT before the end of this year. Reagan has said the United States late this year may exceed the treaty limits on the number of B52 bombers that can be equipped with air-launched cruise missiles.

Adelman opened the session by saying the United States and Soviet Union "may be turning the corner on arms control," in part because agreement has been reached for U.S. and Soviet arms delegations to meet next week in Geneva.

Next Tuesday, the U.S.-Soviet Standing Consultative Commission (SCC) will open a special session in Geneva that was requested by Moscow to discuss Reagan's announced intent to exceed the SALT II limits.

Adelman said he expected the U.S. representative to the SCC, retired general Richard H. Ellis, former head of the Strategic Air Command, to explain to the Soviets that the SALT decision was based on Soviet failure to comply with that agreement.

The session, Adelman said, could last anywhere from a few days to a few weeks, depending on Soviet intentions.

Soviet Foreign Minister Eduard Shevardnadze said at a news conference in London last week that his government wants to argue that it is not violating the treaty, as Reagan has charged.

A second U.S.-Soviet meeting will begin Friday and include experts discussing verification procedures for underground weapons tests.

Adelman said Soviet agreement to a long-standing Reagan request for such a meeting was a "good sign." But he admitted the two sides had different views of the subject matter. The United States wants to talk about on-site monitoring of underground tests; the Soviets want to discuss monitoring an end to all testing.

Adelman said he opposes any limits on the number of nuclear tests as long as the United States depends on nuclear weapons for deterrence.

Adelman said he does not expect much to emerge from those two meetings.

The most positive recent arms control signs, he said, were the new Soviet proposals presented at the last round of the Geneva arms talks and a letter last month from Soviet leader Mikhail Gorbachev to Reagan.

The positions offered by the Soviets are "not as satisfying as we want," Adelman said, but are sufficent to have the recent arms talks in Geneva as "the best round . . . so far."

The administration, Adelman said, is "looking at some new ideas" to include in its response to the Soviet proposals, although he did not elaborate. The Defense and State departments are reportedly at odds over when and how to respond to the Soviets.