WASHINGTON - The secretary of agriculture for the US state of Iowa expects Vice-President Xi Jinping's ongoing visit to the country will promote the state's agricultural exports through lucrative trade agreements with China.

"The benefits of trade with China are enormous for us. I don't know whether there is an agreement yet, but hopefully, likely and probably, it will be something involving soybeans, pork and corn," Bill Northey, the state's agriculture secretary, said in Washington prior to Xi's visit.

"I am looking forward to building better connections and having longer conversations about what we can do to build more business relationships between Iowa and China," he said.

"Soybeans are the biggest crop and provide the most employment because China is the largest buyer in the world, and that demand has grown in the last 15 years," he said.

China began to import soybeans in 1996, and by 2010, the country was bringing in 54.8 million tons of the beans a year, making it the largest net importer of soybeans in the world.

A change in dietary habits has caused demand for soybeans to soar among Chinese people, who are consuming more meat and oil rather than grains. And soybeans are also used widely in China to produce cooking oil and animal feed.

"Iowa is in the Northwest, and the Northwest has become a stronger region recently in terms of economic growth in the country," he said. "A significant part is due to China."

Iowa's feedlots boast 20 million hogs, and the state's pork trade with China hit a peak in 2008, the year of the Beijing Olympic Games, he said.

"US pork is exported to China, and Iowa is the primary producer, the No 1 exporter."

In 2011, China surpassed Canada to become the largest importer of US agricultural goods, according to the US Department of Agriculture.

Northey said trade with China not only creates wealth for the state of Iowa but also more employment opportunities.

"Our unemployment rate is about 2 percent less than the rest of the country," he said.

There are 90,000 farmers in Iowa, who produce almost 20 percent of the soybean products in the country, he said.

"When you sell soybeans, the demand for soybean also means other crops start becoming valuable as well. I would argue every farmer in the US benefits by having that trade," he said.

Meanwhile, the rising price of soybeans and other agriculture products is a boon to companies that provide services to farmers, he said.

"People in Iowa not only plant crop and sell crops but even sell the seeds that help grow better crops, so we have companies like Pioneer and Monsanto and other seed companies expanding because they see people would pay good prices for good seeds," he said.

The total income of farmers in Iowa was $12 billion in 2002, while it reached double that in 2010, Northey said. "We don't have the final numbers for 2011 yet, but it will close to 30 billion."