U.S. farmers lost one of their biggest customers after China officially cancelled all purchases of U.S. agricultural products, a retaliatory move following President Donald Trump's pledge to slap 10% tariffs on $300 billion of Chinese imports.

China's exit piles on to a devastating year for farmers, who have struggled through record flooding and an extreme heat wave that destroyed crop yields, and trade war escalations that have lowered prices and profits this year.

"It's really, really getting bad out here," said Bob Kuylen, who's farmed for 35 years in North Dakota.

"Trump is ruining our markets. No one is buying our product no more, and we have no markets no more."

Agriculture exports to China dropped by more than half last year. In 2017, China imported $19.5 billion in agricultural goods, making it the second-largest buyer overall for American farmers. In 2018, that dropped to $9.2 billion as the trade war escalated, according to the United States Department of Agriculture.

This year, China's agricultural imports from the U.S are down roughly 20%, and U.S. grain, dairy and livestock farmers have seen their revenue evaporate as a result. Over the last 6 years, farm income has dropped 45% from $123.4 billion in 2013 to $63 billion last year, according to the USDA.

Kuylen, who farms roughly 1,500 acres of wheat and sunflowers, lost $70 per acre this year, despite growing good crops. Current government subsidies only cover about $15 per acre, he said.

"There's no incentive to keep farming, except that I've invested everything I have in farming, and it's hard to walk away," he said.

"When four to five generations ahead of you have succeeded, and you come along and fail, you don't see it as not your fault. You snap."

Zippy Duvall, president of the American Farm Bureau Federation, said China's exit is a "body blow to thousands of farmers and ranchers who are already struggling to get by."

China's exit will most impact U.S. grain farmers. China is the world's top buyer of American soybeans, buying about 60% of U.S. soybean exports last year. Analysts estimate that soybean prices have dropped 9% since the beginning of the trade war. Soybean exports to China have dropped by 75% from September 2018 to May 2019, compared to the same nine-month period in 2017 and 2018, according to data from the USDA.

"It's killing us," said Mark Watne, a wheat and soybean farmer who is president of the North Dakota Farmers Union. Watne said he lost $3 per bushel of soybeans he planted this year.

The U.S. currently leverages 25% tariffs on $250 billion in Chinese goods, while China tariffs on U.S. imports are currently at $110 billion. China will also consider imposing tariffs on U.S. agricultural imports it has already purchased.