CHAMPAIGN, Ill. — American farmers are producing more food than ever, but agricultural research is too focused on increasing production and needs to do better at considering consequences such as water and air pollution, according to a report issued Tuesday by a federal advisory group.

The National Academies' National Research Council report found that farmers are being asked to produce more and more food to sustain the world's population, but with little focus beyond how many bushels of grain or pounds of vegetables or meat they can generate.

"If farmers are going to meet future demands, the U.S. agriculture system has to evolve to become sustainable and think broadly — past the bottom line of producing the most possible," said Julia Kornegay, who chairs the Washington-based council's committee that wrote the report and heads the department of horticultural science at North Carolina State University.

The report broadly recommends that agriculture focus more study on the effects of popular farming practices that can improve sustainability, while at the same time integrating research from a broad range of disciplines and spending more on that broader study.

The report is a follow-up to the council's 1989 study, "Alternative Agriculture." The council advises the federal government on science and engineering.

The new report praises U.S. farmers for producing 158 percent more food now than they did 50 years ago, and it acknowledges what it calls "a remarkable emergence" of innovations that support sustainable agriculture, defined as practices that both satisfy the need for food and biofuel crops while also protecting the environment and improving farming's economic viability.

But the report also says agriculture is nowhere near where it needs to be to meet those goals.

The report recommends tightly focused research aimed at improving agriculture's sustainability — the study, for example, of practices such as reduced tillage, planting cover crops and diversifying crops on individual farms. All are practices that many farmers use to varying degrees, but the report suggests more research to study the effectiveness and consequences of these practices is needed.

The USDA and state universities need to work closely together on such research and increase their study of the economics and social effects of such practices, the authors recommend.

Most current research, the report claims, is conducted to address a particular problem — how to rid soybean fields of a particular weed, or how to increase tomato production while using less water — and two-thirds of public agricultural research spending is focused on such study.

The report's authors also call for a broader, integrated approach to research that's more open-ended and pulls in a variety of disciplines.

In particular, the authors want the USDA, National Science Foundation, public universities and farmer-led groups to set up a research initiative focused on the effects farming has on land and watersheds.

Consumers, the report says, have helped create some such markets by their relatively newfound interest in how their food is grown or raised, and the pressure they place on retailers.

"Those emerging markets can motivate farmers to transition to farming systems that balance and meet multiple sustainability goals," the authors write.

The report says public policies have had only a mixed effect on agricultural sustainability. The USDA should spend more on its own study of the effects of current public policies such as farm subsidies and policy ideas in the bureaucratic pipeline, the report recommends.

The report's authors also looked at U.S. agriculture's experience to gauge its relevance to farming in other regions, particularly sub-Saharan Africa. They call for a similar "systems" approach to research aimed at helping the developing world rather than production-focused research.