The next Green Revolution must be guided by small-holder farmers, adapted to local circumstances and sustainable for the economy and the environment, said Microsoft founder and chairman Bill Gates at the World Food Prize Borlaug Dialogue.

With 75% of the world's poorest people farming small plots of land, Gates and his wife, Melinda, who co-chair the Bill and Melinda Gates Foundation, say they can impact hunger, nutrition and poverty most by making small-holder farming more productive and profitable.

While there is a rush of new commitment to finish the work started by Norman Borlaug's Green Revolution, Gates sees trouble from "an ideological wedge."

"On the one side is a technological approach that increases productivity," Gates says. "On the other side is an environmental approach that promotes sustainability."

Requiring one or the other is a false and dangerous approach, he adds.

"The fact is that we need both productivity and sustainabilty," Gates says.

Gates said his foundation works closely with local farmer groups and is one of the largest funders of sustainable approaches, such as no-till farming, rainwater harvesting, drip irrigation and biological nitrogen fixation.

"The environment benefits from higher productivity," Gates says. "When productivity is too low, people start farming on grazing land, cutting down forests, using any new acreage they can to grow food. When productivity is high, people can farm on less land."

Gates says some insist on an ideal vision of the environment, trying to restrict the spread of biotechnology into Sub-Saharan African without regard to hunger and poverty or what the farmers themselves might want.

"They act as if there is no emergency — even though in the poorest, hungriest places on earth, the population is growing faster than productivity and the climate is changing," Gates says. "We have to develop crops that can grow in a drought; that can survive in a flood; that can resist pests and disease.

"We need higher yields on the same land in harsher weather. And we will never get it without a continuous and urgent science-based search to increase productivity — especially on small farms in the developing world."