In Yaqui Valley, credit unions hold sway among the majority of farmers, McCullough said. In addition to providing loans, crop insurance, fertilizer and seed, credit unions have taken over the government's role in providing technical expertise and management advice.

Valley growers also have a long history of working with the Mexico-based International Maize and Wheat Improvement Center, a world-renowned agricultural research center known by its Spanish acronym, CIMMYT.

But interviews conducted for the PNAS study revealed that most farmers take their cues from local credit unions and not from experts at CIMMYT. As an example, McCullough pointed to a collaborative effort between CIMMYT scientists and farmers to develop a nitrogen diagnostic tool that reduces fertilizer use without sacrificing crop yields.

The device, which gives real-time readings of nitrogen levels in the soil, proved early on that it could save farmers 12 to 17 percent of their profits. Yet most farmers rejected the new technology until CIMMYT researchers finally convinced credit union officials that it was a worthwhile investment.

"The most successful innovations that have been adopted by farmers in the Yaqui Valley have come from collaborations among researchers, farmers and local establishments, like the credit unions," McCullough said. Because of their considerable influence among farmers, credit unions should be included in any effort to effect environmental change in the region, she added.

"The Yaqui case negates the simplistic view of the one-way flow of scientific information from the agricultural research community to the user community," Matson said. "If researchers seek to produce relevant knowledge that ultimately influences decision making, they must recognize the dynamics of the local knowledge system and participate purposefully and strategically in it."

The research was supported with grants from the National Oceanic and Atmospheric Administration and the David and Lucile Packard Foundation.

The Program on Food Security and the Environment is jointly run by the Woods Institute for the Environment and the Freeman Spogli Institute for International Studies at Stanford.