An interagency recommendation on whether to embargo exports of phosphate fertilizer to the Soviet Union will be submitted to the White House this week, Commerce Secretary Philip M. Klutznick told a Senate committee yesterday.

But he refused to reveal that recommendation.

Agriculture Secretary Bob Bergland, however, told the commitee he endorses an embargo. Bergland gave his endorsement through a representative at the hearing.

Klutznick said that "imposition of an indefinite suspension would be an emphatic signal to the Soviets of the gravity with which we view" theirr invasion of Afghanistan. But Senate critics repeatedly asked Klutznick why 45 days have passed without final action on the fertilizer issue since President Carter halted grain shipments to the Soviet.

Although no action on phosphate exports has been taken, the Commerce Department on Feb. 5 began to require a validated license for such exports, which means they must receive prior Commerce approval. Since Carter's grain embargo, no validated licenses are being issued pending a review of export policy.

"The crucial question is whether it makes sense to limit our grain trade while selling the Soviets other materials which would enable them to increase their agricultural production," said Sen. J. James Exon (D-Neb.), who called the hearing of the Senate Committee on Commerce, Science and Transportation. "The administration should address itself to treatment of grain and fertilizers, which are, after all, an important part of the agricultural complex," Exon said.

Sen. John Warner (R-Va.) appeared briefly at the hearing to say that President Carter told him and a group of senators shortly after grain shipments were halted that three areas to be affected by the Soviets' action would be grain, the summer Olympics and fertilizer. Warner said the president told them that a halt of fertilizer exports to the Soviets would take place expeditiously."

Warner said that was why he defended Carter before a group of Virginia farmers the next day.

Exon repeatedly asked Klutznick why three days before the temporary export controls became effective he didn't try to block the passage to Russia of three ships loaded with Occidental Petroleum phosphate products, Klutznick said he didn't believe he had that authority.

Exon also questioned a telephone call Klutznick made to Occidental President Armand Hammer hours before the ships left. Klutznick said he called Hammer to tell him of the impending controls on phosphates. But Klutznick added that he was unaware that a judge who as ruling on a dock workers' boycott of Soviet cargo would allow the ships to sail hours after his call to Hammer.

Klutznick also said that the process for halting phosphate exports was more complicated than the senators realized and wasn't as easy surging U.S. athletics to shun the summer Olympics or stopping grain shipments.

Howard J. Hjort, the Agriculture Department's chief economist, told the senators that American farmers wouldn't suffer this year from a phosphate embargo combined with a halt in Russian shipments of nitrogen fertilizers here.