MAXWELL / DES MOINES, Iowa - Maybe he just feels comfortable in the driver's seat, but Vice-President Xi Jinping surprised his hosts on Thursday when he suddenly climbed into the cab of a tractor on an Iowa farm.

Vice-President Xi Jinping tries his hand at operating a tractor during a visit to the family farm of Rick Kimberley in Iowa on Thursday. Xi is on a five-day visit to the United States. [Photo/Xinhua]?

"I hope everything you plant this spring will have a good harvest when the season comes," said Xi during his visit to the Kimberley farm, about 60 kilometers northeast of Des Moines, Iowa.

The Kimberley family felt "excited and honored but also a little nervous" when Xi toured its multigeneration corn and soybean farm.

"This is a tremendous opportunity for us," said Rick Kimberley, 61, owner of the farm.

The vice-president's amiable manners immediately put the family at ease. Sitting in their living room by a fireplace prior to heading into the fields, Xi chatted with the family.

"How's life here? Is it convenient?" asked Xi about daily life on the farm.

Martha Kimberley, Rick's wife, said Xi was "very personable."

The Kimberley family said it has received delegations from time to time, but never at this high level.

Their grain farm is considered a large farm in the area. Rick Kimberley started farming in 1972 with his father, who purchased this 64-hectare farm back in 1950.

Kirk Leeds, CEO of Iowa Soybean Association, said he hopes this visit will bring the relationship between Iowa and China to "a higher level".

"We are here to help supply to Chinese people," said Leeds, who was on the tour and is going with Iowa Lieutenant Governor Kim Reynolds to China next month on an eight-day trade mission to explore more opportunities in agricultural cooperation.

"We produce more than we consume so we have to rely on trade, and on China, with its population and growing economy. It's great to be its trading partner," said Grant Kimberley, 36, the son of the family who has visited China regularly for soybean business since 2008.

"This visit is about friendship and building a relationship, that's where trade begins," said Grant Kimberly.

By the time they were saying goodbye to Xi, the Kimberley family's nervousness of earlier in the morning had dissipated.

"We want to visit China as soon as the harvest season is gone. We think the visit has built a good relationship already."

Xi encouraged "a long-term and stable" agricultural cooperation between Iowa and China.

"We will be behind you," he said to the Kimberleys as he left the farm.

China and the US should strengthen cooperation in trade and food security as well as enhance exchanges in technology and information sharing, said Xi at a China-US agricultural symposium on Thursday.

The high-level meeting among senior officials and business leaders from both sides focused on food security, food safety and sustainable agricultural development, which lifted cooperation to a new height.

"It will have great significance and far-reaching influence if the cooperation between the two large agricultural countries can rise to a strategic level in order to achieve the mutual benefit and shared progress," he said during the speech at the World Food Prize Hall of Laureates.

"China attaches great importance to food security, and ensuring a sufficient food supply for 1.3 billion people," Xi said.

Xi stressed that the two sides need to strengthen cooperation in technology to improve agricultural productivity, establish a fair market to enhance trade ties and improve communication in global agricultural hotspots.

Due to climate change and the unstable global financial situation, the deepening cooperation between China and the US will help stabilize domestic economic operation and speed up global economic recovery, he said.

During the event, US Agriculture Secretary Tom Vilsack and China's Minister of Agriculture Han Changfu signed a Plan of Strategic Cooperation that will guide the two countries' agricultural relationship for the next five years.

In 2011, China became the top market for US agricultural exports, and the value of US farm exports to China supported more than 160,000 American jobs, according to US Department of Agriculture. China is the largest buyer of US soybeans, purchasing about 60 percent of a typical export crop.

After his stay in Iowa, Xi flew to Los Angeles - a critical gateway to the growing Chinese market - and visited the dock operated by the state-run China Shipping Group.

The Chinese delegation was expected to sign more purchase agreements in Los Angeles on Thursday.

Zhou Wa contributed to this story.