Sustainable agriculture is not a new idea, but it has been getting a lot of attention lately because of environmental movements, says an international authority on range land management.

"You must balance the economic constraints with the ecological constraints," said Gerald Thomas, former president of New Mexico State University and native of Medicine Lodge in Clark County. He spoke during the U.S. Sheep Station's silver jubilee symposium in Idaho Falls Friday.Thomas grew up just 15 miles away from the sheep station and could see it from his father's cattle ranch. After graduating from the University of Idaho in 1941, Thomas spent several years working for the Soil Conservation Service.

Thomas said sustainable agriculture involves meeting today's demands for food and fiber, while still conserving the resource base for future generations.

The idea was discussed by Soil Conservation Service technicians 50 years ago but has swept through the international community as pressure on the Earth's limited resources increases, he said.

Livestock grazing on public lands can be a part of a sustainable agricultural system, despite criticism by some groups, he said.

The condition of the Western range has improved substantially since the 1930s, when federal legislation was passed to regulate grazing on public lands and can support livestock grazing.

At the time, ranchers resisted attempts by the government to control their historic grazing rights but realized there was too much livestock on the range and too much competition for vegetation.

Range wars between cattlemen and sheep ranchers broke out in certain parts of the country. Thomas remembers his father blaming the sheep for getting the good graze first.

However, grazing is part of the natural ecosystem, allows for a natural diversity of vegetation on the range and livestock is a necessary part of the world's food source, he said.

Western ranges have always supported grazing, he said. Buffalo and bison grazed it before livestock was ever introduced. Grazing seems to improve biological diversity of vegetation by keeping some plants under control and allowing others to develop.

Some researchers are studying ways to manipulate vegetation through grazing practices and adapting livestock to certain types of plants.

"The challenge is to understand the impacts and adjust activities based on research," he said. "There is too much emotion and not enough analysis of the data base."

Long-term research, like that being conducted at the sheep station, is essential to manage rangelands and develop sustainable agriculture methods, Thomas said.

"You can't blame someone for something if you don't know what the base looked like," he said.