Congress' nonpartisan research bureau has weighed in on the effect of retaliatory tariffs on U.S. agriculture in a new report that says any export losses “would be a concern” because sales abroad account for 20 percent of U.S. farm income. After the U.S. imposed Section 232 tariffs on steel and aluminum, several countries retaliated with their own duties on U.S. products and, in some cases, targeted U.S. agriculture and food products. China – one of the largest importers of U.S...