The Trump administration’s announcement last week of a $12 billion-aid package for struggling farmers impacted by Chinese retaliatory tariffs on U.S. soybeans and other products could create a situation similar to China’s huge corn and wheat surpluses. The proposal, which essentially returns USDA’s Commodity Credit Corporation to its initial role of the 1930s, calls for direct payments to farmers to offset their reduced incomes from low prices as well as expanded trade promotion activities overseas and increased purchases of surplus commodities. Food banks and other food assistance agencies may relish having additional resources for serving their communities, but USDA buying up surpluses in a year when forecasts for corn,...