On the morning in January, 1980, when he got his copy of The Wall Street Journal, which brought news of the U.S. embargo on grain shipments to the Soviet Union, an Illinois farmer named John R. Block wrote "B-l-a-c-k F-r-i-d-a-y" in large letters atop the front page.

At the time, Block also was the Illinois director of agriculture. He denounced the embargo then and he never stopped denouncing it, even after he became President Reagan's secretary of agriculture a year later.

At the White House, in cabinet meetings, on Capitol Hill, Block kept arguing against the embargo, kept saying he was optimistic that it would be lifted but, along the way, began to appear as a man who had vaguely lost his grip on political reality. It put him directly in conflict with Secretary of State Alexander M. Haig Jr., who, in his espousal of a get-tough policy with Russia, opposed lifting the embargo.

All the while, Block kept that marked copy of The Wall Street Journal at his side. Yesterday, describing himself as "happy beyond comprehension," he tossed aside the old newspaper and gave every sign of being a man vindicated as the president had decided in his favor.

As Block was addressing reporters, even before the embargo was officially lifted, aides were meeting elsewhere in the Department of Agriculture building with Soviet trade representatives -- another sign that Block was correct in reading signals of their willingness and need to buy U.S. grain.

Those talks could lead to more purchases of corn, wheat, and soybeans by the Russians and, Block said hopefully, might pave the way for an extension of the bilateral grain trading agreement that will expire Sept. 30.

From the secretary's point of view, in the context of his promotion of "free-market" trading philosophy, the embargo absolutely had to be stricken to get the administration's farm program off dead-center.

A new agreement with the Soviets, obviously, could not be negotiated as long as the embargo remained in place. But more importantly, perhaps, the administration's efforts to get a farm bill through Congress were being chewed in the fangs of the embargo.

Loyal Republicans in the House and Senate have rebelled openly at some of the austere proposals in the administration's farm proposal, in part because of their unhappiness over Reagan's continuation of the grain-trade limitations.

That resistance, in combination with the prospect of a record wheat crop this year and generally favorable harvests of other major commodities, carried portentous signs for the White House attempt to reduce subsidy and lessen government involvement in farmers' affairs.

With the embargo now swept away, the picture changes. As Block noted yesterday, for the umpteenth time since becoming secretary, the embargo has been a serious psychological impediment to farmers and to American trading partners overseas. It has hurt the GOP on Capitol Hill, too.

So it was a good week for John R. Block, as he ditched his Black-Friday newspaper. But anyone paying close attention should have known it had to end that way. He began the week by running the Boston Marathon in 3:05 -- not bad at all for a man of 46.