Their case was the first to go to trial. Thousands of other corn producers and traders also are seeking damages over China's non-approval of the agrochemical giant's corn seeds for importation.
Lawyers for the corn producers said in a statement that the verdict was "only the beginning." They have claimed that damages for farmers nationally totaled $5.77 billion, according to court papers.
Syngenta said it will appeal the verdict, which included only compensatory damages and no punitive damages.
"We are disappointed with today's verdict because it will only serve to deny American farmers access to future technologies even when they are fully approved in the U.S.," Syngenta said in a statement.
In 2010, Syngenta began selling in the United States a strain of insect-resistant genetically modified corn called Agrisure Viptera. It started selling a second strain called Agrisure Duracade in 2013.
In their lawsuit, the Kansas corn farmers accused Syngenta of negligently commercializing the corn seeds before obtaining export approval in China, a major importer.
In 2013, Chinese officials detected Viptera in U.S. corn shipments. The country began rejecting shipments containing millions of metric tons of U.S. corn because they contained the strain, which was unapproved for import, the farmers said.
Nearly 90 percent of corn in the United States, the world's top grains producer, is now genetically engineered, according to the U.S. Department of Agriculture, as farmers embrace technology that helps kill weeds and fight pests.
The loss of the Chinese market caused U.S. corn prices to plummet, leading to over $5 billion in losses for corn producers, the farmers' lawyers said. China did not approve Viptera until December 2014, while Duracade is still pending approval.
Syngenta denied wronging. It said at the time that no company had ever delayed launching a U.S. approved corn product in the United States just because China had yet to approve its import.
It also said the decline in sales to China was offset by exports to other countries.
The case is In Re: Syngenta AG MIR 162 Corn Litigation, U.S. District Court, District of Kansas, No. 14-md-02591.
(Reporting by Nate Raymond in Boston; Additional reporting by Tom Polansek in Chicago; Editing by Paul Simao; Editing by Chizu Nomiyama)