A major step toward breaking down some trade barriers was taken this week by the United States and Japan with the signing of a long-anticipated economic agreement.

In essence, it calls for Japan to increase its imports and lower some tariffs on U.S. beef and oranges over the next six years. This means a bigger market for U.S. products and an improved standard of living and lower prices for the Japanese.But more than that, the agreement, as Cabinet Secretary Minister Keizo Obuchi pointed out, "reconfirms that the United States and Japan are able to solve their problems through joint effort." The signing of the pact, to be completed within the next few weeks, have been particularly hailed because the agreement has been long-sought.

The pact has further significance, in that it was achieved without any of the onerous "dumping" implications than tend to create unrest among nations. Under the agreement, Japan will nearly double its imports of beef by 1991 and phase out its Livestock Industry Promotion Corporation, that controls most beef imports.

To give Japanese farmers time to adjust, Japan will be allowed to set tariffs on beef of 70 percent in 1991, 60 percent in 1992, and 50 percent in 1993. The agreement can be fully implemented without hurting Japanese farmers, Obuchi said.

At the same time, the value of U.S. beef exports to Japan are expected to double, at the least, to more than $1 billion a year as a result of the pact, giving U.S. farmers a needed boost.

And the market for fresh U.S. oranges will be expanded by 22,OOO tons annually to 192,000 tons in 1990. After that, fresh U.S. oranges will be permitted in unlimited quantities at a current tariff rate of 40 percent in season and 20 percent off season. Juice quotas would be phased out.

In addition, the United States also received compensation on tariffs for other farm products in return for concessions on allowing Japan to slowly phase out its tariffs.

The trade agreement seems to represent one of those rare times in negotiations when each side gets the best of two worlds.

Given all the pluses, it's little wonder that U.S. trade representative Clayton Yeutter hailed the pact as "a landmark agreement in U.S.-Japanese economic relations."