President-elect Donald Trump’s vow to “drain the swamp” in Washington could begin with the Agriculture Department. Federal aid to farmers is forecast by the Congressional Budget Office to soar to $19 billion in 2017. Farmers will receive twice as much of their income from handouts (25%) this year as they did in 2013, according to the USDA. Whoever Mr. Trump names as his agriculture secretary should target wasteful farm programs for spending cuts.

Here are a few of the most egregious examples:

•...