Prime Agricultural Areas Threatened, Study Says : Conservation: American Farmland Trust’s report says California is especially vulnerable. The group urges that land management plans emphasize more compact urban growth.

Patchwork suburban sprawl is gobbling up some of the nation’s most productive farmland, with California’s Central Valley and coastal counties among the most threatened agricultural regions, a conservation group warned in a study released Wednesday.

A combination of population growth, rapid development and a lack of long-range planning has led to the loss of this “urban edge” farmland, which accounts for more than half of the country’s gross agricultural sales, according to a report by the American Farmland Trust.

California, with its unique soil and climate conditions, is particularly vulnerable to the conversion of farms to non-agricultural uses, the group said. In the Central Valley alone, population increased 33% during the 1980s while farmland declined by about 616,000 acres, according to the Washington-based group.

Unless steps are taken to slow these trends, financial pressure on farm owners to sell to developers will intensify, creating an even wider swath of land vulnerable to suburban sprawl, the report said.

The group called for more cooperation between federal, state and local governments to designate prime farmland most threatened by development and urged that land management plans emphasize more compact urban growth.

It also called on the U.S. government to enforce the Farmland Protection Policy Act, designed to slow the loss of agricultural land to government projects, and to fully fund the Farms for the Future Act, which authorizes federal assistance to farm preservation programs.

Frank Grossi, president of the American Farmland Trust, said Wednesday that the Ronald Reagan and George Bush administrations did not support either program. But he hopes for a warmer reception from the Clinton Administration, particularly from Deputy Secretary of Agriculture Richard Rominger, a farmer from Winters, Calif., who until recently sat on the organization’s policy-making board.

“I think the American Farmland Trust is providing a great service in pointing out these threats,” Rominger said Wednesday. “This is one of the areas that the USDA needs to pay more attention to . . . and something that this Administration should pay more attention to.”

Grossi, who operates a Marin County farm 25 miles north of the Golden Gate Bridge, conceded that the apparent abundance of American food and farmland “will be a challenge to selling” the organization’s recommendations. But he said that short-term economic forces should be balanced by long-term agricultural needs.

Grossi urged that government money be invested to make U.S. cities more livable, thus slowing the steady population shift to the suburbs.

“This is not so much a population problem as a distribution problem,” Grossi said.

The eight-month study found that 56% of the nation’s total agricultural sales come from “urban-influenced” counties, where 90% of the U.S. population lives.

“The most surprising thing we found is that a significant percentage of the food we eat is grown, not deep in the countryside, but on the edge of our cities,” said Ed Thompson, public policy director for American Farmland Trust. More than 86% of domestic fruits and vegetables and almost 80% of the nation’s dairy products come from these counties, Thompson said.

To find hot spots nationally, researchers identified counties with both high productivity and high population growth and developed a list of 12 most-threatened areas.

On that list, the Central Valley region was rated No. 1 and an area of California coastal counties--virtually the entire coast between San Diego and Marin counties--was rated No. 3.

The Central Valley produces more than 250 commodities, including much of the nation’s year-round supply of fresh and processed fruits and vegetables.