Zoellick said it's "now or never" for negotiations among ministers attending the World Trade Organization talks.

"Progress on agriculture is paramount," Zoellick said in a statement. "An open and fair system would create opportunities for developing country farmers to expand production, for consumers in all countries to lower prices, and for governments to save on the costs of subsidies, improving budgets

"Both developing and developed economies stand to gain from lower barriers to goods and agriculture."

Zoellick urged negotiators to resist pressure for protectionism, saying that would return the world to "economic isolationism" and "would reap the losses, not the gains, of globalization."

Talks got under way Monday.