Farms in the semiarid western United States produce a large portion of the nation's food and fiber, most with irrigation. Yet, as available water supplies shrink and competing demands for water increase, western agriculture faces an uncertain future.

Scientists from throughout the world convened last week to discuss the water crisis in agriculture and explore how new research can help farmers produce more with less. Their discussion was part of the annual meeting of American Association for the Advancement of Science, held last week in San Francisco .

"There is no question that the greatest challenge for agriculture in the near future will be the availability of adequate supplies of water of sufficient quality to support agricultural production," said Stella M. Coakley, an associate dean of the College of Agricultural Sciences at Oregon State University and one of the panel organizers.

Coakley, a plant pathologist with a specialty in climatic effects, sees the issues of water security and food security converging in agricultural areas around the world, including many parts of Oregon .

Panel members described how an increase in population, urbanization, and environmental consciousness has increased various demands for water, outbidding and reducing the water available for agriculture. Shrinkage of groundwater resources and a prolonged drought have aggravated the situation, and the greater frequency of more severe droughts predicted by some global climate change models are a cause for great concern.

In addition, global warming appears to be increasing the water requirements of plants.

Ray Huffaker, from the School of Economic Sciences at Washington State University , addressed the changes needed in federal water laws and policies to protect water rights and to enhance efficiencies in water distribution, allocation, and marketing.

Bert Clemmens, from the Arid Land Agricultural Research Center in Maricopa, Ariz. , discussed actions and technologies that could reduce field losses of rain and irrigation waters.

Robert Evans, from the USDA Agricultural Research Service in Sidney , Mont. , described how competition for water will soon require a major shift from maximizing agricultural productivity per unit of land to maximizing productivity per unit of water consumed. He outlined new methods to increase water use efficiency of crops, technologies that include site-specific water management.

John Bennett, from the International Rice Research Institute in the Philippines , spoke about his research identifying genes for drought tolerance in rice and efforts to breed rice for water-limited ecosystems.

John Letey, a professor emeritus of soil and water sciences at the University of California, Riverside, spoke of his work modeling soil salinity and reuse of saline and other impaired waters.

"These are some examples of what we might do to address the water security in the West," Coakley said.