DOUBTLESS you have not been paying much attention lately to the subject of soybeans. But you may have noticed that the Wholesale Price Index rose by a dismaying 1.1 per cent again in April, and this time the soybean market was a principal contributor. As an illustration of the way the American economy is working, there's a lot of instruction in the soybean's recent adventures.

Soybeans don't often turn up in the grocery stores in this country. But they are an exceedingly efficient source of protein, and they're being used in rapidly rising quantities here and around the world as feed for animals and poultry. As the world's standard of living rises, people eat more meat - and the demand for soy meal goes up. A year ago the price was low, and farmers reacted by planting some of their fields in more profitable crops like corn. Then last summer's dry weather diminished the harvest still further.

A lot of other countries now depend heavily on American soybeans. Our biggest customer, Japan, buys on a very predictable schedule, but there have also been unexpectedly large sales over the past year to the Soviet Union, which relies on imported beans to help meet its fluctuating shortages of protein. China, the land from which Americans originally brought the soybeans, is now an importer, and this year for the first time made large purchases here.

You could have gotten a bushel of soybeans a year ago for a mere $4.80. Now it will cost you $10. For the U.S. Department of Agriculutre, the main question is whether the present supply will last until another harvest arrives next fall. The department calculates that there will be enough - but only barely. Uncertainty on this crucial point is also pushing prices upward.

It's happened before. In 1973, the Nixon administration neglected the subject, then realized that the crop was oversold and, in a panic, slammed down an embargo. There was a bitter reaction abroad - particularly in countries like Japan, where soy products are a staple of the human diet. The present administration wants to avoid that, of course, and certainly it doesn't want to do anything that might discourage farmers from planting the huge crop on which it is counting for next fall. Last month someone asked the Secretary of Agriculture, Bob Bergland, whether he would consider an embargo this year. "Absolutely not," he immediately replied.

He's right. But the question suggests the dilemma. Unlimited food exports mean higher prices for Americans this season. And yet the world's hunger for protein is rising, and the American soybean crop is a major source of the world's supply. It's a matter of moral responsibility as well as economics. Sometimes the cost of controlling inflation is more damaging than the inflation itself.