There is a missing element in newspaper coverage, and it resists definition. It is the story behind the story, the stuff of a thousand conversations in this city's bars daily, the how of a story, the anecdotes, the back-and-forth between editor and reporter that produces the odd 20th-century artifact known as a news story.

From June 7 to June 12, for example, The Post ran a six-part series of articles on the unlikely subject of corn -- unlikely, at least, for this paper whose circulation area could hardly be called the Farm Belt.

The corn stories were written by Ward Sinclair, a veteran reporter who came to The Post four years ago, after reporting and editing in Mexico City, Wichita, Tampa and Louisville, where, for the Courier Journal, he covered Washington for eight years.

Early this year, Sinclair was assigned to cover farm issues for The Post's national staff. It is a unique assignment for a major East Coast newspaper. It originated in 1977 when Dan Morgan was given the responsibility of covering the enormously important story of agriculture and its significance to the nation.

Over coffee one day, Morgan suggested to Sinclair that the industrialization of corn might make good reading. Sinclair did some research in the Agriculture Department and was fascinated by pages of commercial uses for the corp. He wrote a memo to his editors, who liked the idea, and in February he made the first of his trips to the Corn Belt.

In Galesburg, Ill, half a dozen local farmers, somewhat astonished that The Washington Post was covering their industry close up, kept a morning appointment with Sinclair, despite knee-deep snow and temperature of -40 degrees.

In a later interview, another Illinois farmer, Bill Fugate, couldn't answer some of Sinclair's questions, so he drove the reporter 60 miles in a pickup truck to a friend who could.

At the Univerisity of Illinois, informative scientists Sinclair describes as "world class" were pleased to introduce a visiting professor from the People's Republic of China who came up with a quip on the Soviet Union's agriculture problems: "They plant in the U.S.S.R., but they can only harvest in the U.S.A."

When the series was written and published, Sinclair reflected on the people and the material he had covered: "I found myself proud of those farmers, the researchers and the manufactures. They are doing heroic work, and they do it beside the corn fields because that is where it has to be done. It was similiar to a feeling I had last year when I covered the Cuban refugees. Government policy was bungled, but Coast Guardsmen were risking their lives rescuing Cubans, despite high winds and seas. They were my country men, and I was proud of them."

Not the stuff of major news, you say? You are right. The medium doesn't allow that kind of thing, and if it tried it could easily be overdone. Unless written with great skils, readers could quickly tire of the I'll-tell-you-how-I-did-it story. Still, this kind of information is real and warm and is connected somehow to our own humanity. But it has no place in news coverage.

Mistakes can be corrected in this business. For example, last Friday The Post reported criticism of a Pulitzer-Prize-winning article on the shooting of Allard Lowenstein. The Post failed to mention that it had bought and published the original article. And this week there was the zany mistake that resulted in The Post's publishing a silhouette of a Soviet vessel atop two of the articles in the series on the U.S. Navy. Omissions and commissions get corrections with regularity.

But there is a blind spot, perhaps an inability colored by self consciousness, in this medium when it has opportunity to write about the anxieties and compassion of its own enterprises. Failure to find a way to do that means that newspapers to do a lousy job of covering themselves.