Washington ? Just 3 percent of the nation’s farms — those with sales of more than a half-million dollars a year — are producing more than 60 percent of America’s agricultural goods, according to the government’s most in-depth look at who grows what.

While farming remains an occupation dominated by middle-aged and older men, women are making some inroads, the Agriculture Department said Thursday in its latest Census of Agriculture. The census is done every five years; the latest numbers cover 2002.

The 70,600 farms and ranches with annual sales of more $500,000 produced about 62 percent of the nation’s agricultural products in 2002, the report said. In 1997, when the last previous survey was done, that share was 56.6 percent.

The department said U.S. farms produced $200.6 billion in products in 2002, an average of about $94,200 for each farm. That was a gain of about $3,400 from 1997.

As it has in past surveys, the number of farms and farm acreage continued to shrink. There were about 2.1 million farms in 2002, 87,000 fewer than 1997. Land devoted to farming and ranching in 2002 totaled 302.7 million acres, about 16 million acres fewer than five years ago.

The number of tiny farms, with fewer than 10 acres, declined by 26,000 during the five-year period to 179,000. There also were 18,000 fewer middle-sized farming operations of 500 acres to 1,000 acres than five years ago. But the number of large farms with 3,500 acres or more grew by 18,000 during the five years to 78,000 in 2002.

The data offered new evidence that American farming is being powered more and more by size, such as bigger and more efficient equipment that larger producers can afford. Even though such equipment is expensive, the efficiencies accompanying them are driving down the cost of production.

“That middle group is so distressed,” said Chris Hurt, an agriculture economist at Purdue University. “Many would like to grow to become larger commercial farmers, and drive their costs lower.”

The figures also show that smaller farmers still can make a living if they find a niche, such as selling direct to consumers through farmers markets or other methods, Hurt said. The census said direct-to-consumer sales rose by more than $220 million, topping $812 million in 2002.

The department also offered a snapshot of the average farm. It grew by 10 acres since 1997, to 441 acres. It produced $97,320 in sales and government payments in 2002. It earned an average net cash income of about $19,000.

There was a wide variance between poor farms and rich ones. The poorest, farms with sales of less than $1,000 in 2002, wound up with an average loss of more than $7,100. The richest, with sales of $1 million or more, averaged more than $698,000 in net cash farm income.

About 1.2 million people considered themselves full-time farmers in 2002, an increase of about 180,000 from 1997. The average age of farmers was a bit over 55, more than a year older than the average age of farmers in 1997. Only 6 six percent of farmers had yet to reach their 35th birthday.

About 73 percent of farmers were men, but women are a growing presence. In 2002, almost 237,200 women were principal operators, the main makers of day-to-day farming decisions. That’s 27,000 more than in 1997.