Iowa lawmakers continue to work to add an amendment in a wide-ranging federal disaster bill to provide compensation for farmers who lost stored grain in the massive flooding in southwest Iowa and other parts of the Midwest.

The disaster bill, which has been held up in Congress by political fighting over additional aid to Puerto Rico, is likely to contain aid for farmers who lost stored grain, Iowa Sen. Charles Grassley said last week in a call with ag media. “I’ve been told by leadership in the...