For the past generation, farm policy has been discussed little, if at all, in presidential campaigns. Other than occasional expressions of support for ethanol policy ahead of the Iowa caucuses, candidates have tended to focus on issues that resonate more broadly with voters such as the economy, health care, reproductive rights and gun control, even in farm states.

By contrast, farm policy was very prominent in President Donald Trump’s remarks at an Iowa rally last week. Implicit in the comments were the degree to which the farm economy has been caught in the crossfire of the trade war prosecuted by the president with China. Per usual, Mr. Trump wasn’t subtle as he made his case: “And I gave you $28 billion. Say, ‘Thank you very much, President Xi.’ It came right out of China. And because of that, everybody’s happy in Iowa. I just hope you remember that on Nov. 3. Hope you remember. Nobody else would have done it.” And later, “I don’t want to say it too loudly, $28 billion, I gave you $16 (billion) and $12 (billion).”

Mr. Trump said growers have been supportive of his trade policy, an assertion mostly borne out in polls. He also acknowledged growers’ deep discomfort with relying so heavily on government largesse. Quoting supportive farmers, he said admiringly, “‘We don’t want subsidies, sir; all we want is a level playing field.’” Whether Mr. Trump succeeds or fails next month in his bid for reelection, the path toward a level playing field with China is anything but clear.