America’s Glaring Weak Spot in a Trade War? The Lowly Soybean

President Trump is spoiling for a fight with China on steel and aluminum. But in China, it’s looking like a good year to pick a fight with U.S. farmers. The trick? Picking winners from losers in an agricultural trade war.

Trade tensions between Washington and Beijing are rising. The Trump administration slapped tariffs on solar panel and washing machine imports in January, and is poised to further restrict imports of steel and aluminum—markets in which China is a dominant player. U.S. metals executives were summoned to...