WASHINGTON -- Prince Charles is in Washington talking about environmentally friendly farming, and he says it's a change from giving royal wedding toasts. After greeting students at Georgetown University on Wednesday, Charles spoke passionately about organic and sustainable farming for almost an hour. He made only brief reference to the worldwide hubbub over his son Prince William's wedding to Kate Middleton last week. Charles called his remarks "a change from making embarrassing speeches about my eldest son during wedding receptions." In his speech, the Prince of Wales criticized government subsidies for large-scale agriculture and encouraged more government and business support for organic and environmentally-friendly food production. The United States spends tens of billions of dollars a year on such subsidies. Charles, who will meet with President Barack Obama later Wednesday, is in Washington for a three-day visit. On Tuesday, he visited the Supreme Court and an urban farm in Washington. The small farm grows produce for low-income residents. At Georgetown, he shook hands with students who stood in the heavy rain hoping to get a glimpse of him as he arrived. He called rising hunger and obesity problems around the world an "increasingly insane picture" and proposed less use of chemical pesticides, artificial fertilizers and antibiotics. He criticized industrial pollution and global dependence on oil. "The point, surely, is to achieve a situation where the production of healthier food is rewarded and becomes more affordable and that the earth's capital is not so eroded," Charles said. He praised first lady Michelle Obama's campaign to combat childhood obesity and hunger along with U.S. manufacturers' efforts to produce healthier foods. "You cannot help but feel hopeful when such huge corporations like Wal-Mart back local sourcing of food and decide to stock their shelves with sustainable or organic produce," he said. "Industry is clearly listening."