When President Trump on Friday announced that the U.S. will impose a 25 percent tariff on $50 billion of Chinese goods, China swiftly vowed to retaliate with their own levies on American products. As a trade war between the world's two biggest economies intensifies, perhaps no one is more in the line of fire than U.S. farmers.

Chinese tariffs on U.S. soybean exports to the People's Republic could cost Iowa farmers as much as $624 million, according to Donnelle Eller, an agriculture reporter with the Des Moines Register.

"Farmers are extremely concerned about the loss of potential prices, loss of market and what that might do to prices going forward -- especially going into the fall when they will be harvesting their crops," she told CBSN, noting that Iowa is the No. 2 soybean producer in the U.S. "Farmers are really feeling lucky if they can break even, and this is sort of piling bad news onto more bad news."

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An estimated one out of every three rows of U.S. soybeans is shipped to China, Eller said, citing farmer estimates.

Iowa's agriculture sector also could suffer as a result of China imposing a tariff on U.S. pork exports, with Iowa that country's biggest pork producer.

Chinese buyers are canceling orders for U.S. soybeans amid the prospect of higher costs. At the same time, farmers in China are being encouraged to plant more soy, apparently to help make up for any shortfall from the U.S.

It can take a month or longer for soybean shipments to travel from the U.S. to China. Any soybeans en route to China now could be hit by the tariff by the time they arrive.

President Trump says the tariffs on Chinese imports are a response to the country's unfair trade practices, including what administration officials contend are requirements that U.S. companies share their intellectual property in exchange for access to China.

-- CBS News' Jillian Harding contributed to this report