The United States is not the only exporter facing hurdles selling corn to China.

Brazil, a top soybean exporter to China, is working to build its corn-exporting capacity. But like the Unites States, it has also found China a tougher market to crack, according to Alfredo Navarro, the U.S. Grains Council’s (USGC) Re­­presentative in Brazil.

Navarro...