Agricultural markets received a jolt of optimism last week with news that China is lifting its sanctions on U.S. sorghum and will buy “massive amounts” of U.S. products, including farm commodities, as the result of talks to reduce the trade disparity between the world’s two largest economies. But Trump administration officials cautioned that there’s still more work to do before trade relations between the countries are normalized.  

“I do not want people to get overly excited,” said Ted McKinney, U.S. Under Secretary of Agriculture for Trade and...