WASHINGTON - US Agriculture Secretary Tom Vilsack announced Thursday that he would lead a trade mission to China at the end of March to strengthen business ties.

The trade mission will be made up of more than 40 US companies and representatives from six states as well as a senior official from the Agriculture Department.

They will travel to the Chinese cities of Chengdu and Shanghai on March 23-28.

In 2011, China became the number one market for US agricultural goods after purchasing $20 billion?worth of US agricultural exports. Sales of US food and agricultural products to China grew by 80 percent in three years.

Last month, Chinese Vice President Xi Jinping and Agriculture Minister Han Changfu attended the first China-US Agricultural Symposium in Des Moines, Iowa. Han and Vilsack signed a Plan of Strategic Cooperation designed to guide the two countries' agricultural relationship in the next five years.

Monsanto, the world's biggest seedmaker, plans to boost investment in China because of the newly-drafted government policy, Chief Technology Officer Robb Fraley said on a seminar recently.