In an interview with The Washington Post on March 27, President reagan said he wanted to keep his campaign promise to lift the grain embargo against the Soviet Union, but didn't see how he could do it "without sending the wrong signal."

A month later, he lifted the embargo. What about the signal?

No problem, Secretary of Commerce Malcolm Baldrige said on ABC's "Issues and Answers" last weekend, adding: "It was not [Reagan's] embargo in the first place . . . . It was Jimmy Carter's." As for the something-for-nothing argument raised by many critics of the move, Baldrige maintained the president "never stated it would take a quid pro quo. the fact is he didn't think it was an effective enough tool."

Now if that's all there was to it, you could argue, as both Baldrige and Secretary of State Alexander Haig have done, that the Soviets are getting -- in other ways -- the message of a new Reagan-style toughness and of revived American resolve. They are getting, and the hard line on El Salvador and the Persian Gulf.

But that's most definately not all there was to the administration's lifting of the grain embargo. Examine its context and timing, and the way at least some independent experts think it is likely to be read by the Soviets. The lifting of the embargo then takes its place alongside the sale of AWACS to Saudi Arabia as further disturbing evidence of the administration's continuing inability to deal coherently and consistently with the making of foreign policy decisions.

Had the administration simply treated the lifting of the embargo as a campaign commitment, pure and simple, and an impediment to passage of vital economic and agricultural measures, that might have been, well, understandable. Ditto, if the argument had been that it was originally a reprisal for the Soviet invasion of Afghanistan -- a reprisal that was having no demonstrable effect.

But having dismissed the embargo as a misguided attempt by Carter to affect events in Afghanistan, President Reagan nonetheless got nervous about lifting it for what might appear to be squalid domestic political considerations. So he tried to find a nobler, foreign policy rationale by tying the removal of the embargo to Soviet restraint in Poland.

Baldrige should be the first to know. He may be right about the president's never having publicly insisted on a "quid pro quo." But he is, as commerce secretary, a reliable articulator of administration policy. And only 10 days or so before the embargo was lifted he was saying publicly on Cable News Network that the president would not remove the embargo "without some sign that satisfied him that there was in effect some movement for private assurance from the U.S.S.R. about Poland."

Nothing public, Baldrige was careful to note. But "it's very difficult to take [the embargo] off unless there is some kind of quid pro quo."

Well, the fact is, as Baldrige himself conceded after the fact, there was no "quid pro quo." Nor, in the opinion of most Soviet experts I've talked to, could there ever have been any dependable answer from the Soviets on what they may do in their own interests in Poland. Neither the Polish Communist government nor the leaders of the Solidarity movement nor the leaders of the Solidarity movement can be confident of their ability to control the potentially explosive forces for reform.

"American economic sanctions, real or threatened, would not be a major consideration for the Russians," says one Soviet expert, "if the Russians thought the authority of the Polish Communist government was seriously in doubt. They will do what they think they have to do, at whatever cost, for the security of the Communist bloc."

If the expectation of some guarantee of Soviet restraint in Poland was always an unrealistic "quid" to expect in return for the grain embargo "quo," what was happening at the moment of the lifting of the embargo is even more devastating to the administration's rationale.

Mikhail Suslov, a noted Kremlin hard-liner whose power is probably second only to that of Leonid Brezhnev himself, had just returned from a sudden one-day trip to Warsaw to talk to Polish leaders. The ensuing communique was read by knowledgeable authorities in Washington as significantly devoid of the customary expression of confidence in the Polish government's competence to keep order.

Almost simultaneously, the official Soviet news agency Tass was accusing the Polish government of "revisionist" tendencies. In Communist political circles, there can be no darker crime. The Reagan administration, in short, was seeming to reward the Soviet government at precisely the time when the Soviets were increasing their efforts to intimidate the Poles. And it was giving every appearance of doing so for the sake of domestic politics.

The president was right the first time. The way he lifted the grain embargo sent precisely the "wrong signal" -- to our allies as well as to the Soviets -- from a great power supposedly seeking to reestablish its influence and prestige and reputation for reliability.