Ferrellgas Partners of Kansas City said revenue in its recent quarter rose 20 percent to $722.1 million because of higher propane and gas costs, but earnings were up just 1.6 percent. The CEO called it “a very challenging quarter.” There was a propane shortage that caused price spikes in the Midwest and Northeast this past winter, amid record-low temperatures. Ferrellgas is one of the nation’s largest propane distributors, including its Blue Rhino grilling tanks. For the quarter ended April 30, Ferrellgas Partners earned $45.4 million, or 57 cents a unit, up from a year-ago $44.7 million, or 56 cents a unit. Its partnership units trade like shares of stock.