(FORTUNE Magazine) – Feel guilty when you toss out your kids' disposable diapers? Then compost them into the rich mulch shown in the magazine. That was the message behind an ad campaign that Procter & Gamble, maker of Luvs and Pampers, ran in several national magazines this year. The ads were another salvo in the company's seemingly endless battle to defend its disposable diaper business -- and 18%, or about $4 billion, of its total sales. The ad made a lot of greens see red. The objection: There aren't enough recycling facilities in the U.S. capable of making mulch out of the some 15.8 billion disposables Americans discard a year. New York City consumer affairs commissioner Mark Green blasted P&G for creating the impression that city dwellers could compost their disposable diapers and other garbage when there are no such facilities in the entire state. The company has invested $20 million to learn more about what a spokesman calls ''composting technology.'' P&G hopes to encourage communities to set up compost plants that will accept used diapers. At present, only ten such facilities exist. Minnesota has four of them, one in St. Cloud. Florida has two, in Pensacola and Bushnell. Wilmington, Delaware, has one, as do Des Moines; Portage, Wisconsin; and Big Sandy, Texas. These plants mulch the diapers along with other garbage like food. They sell the end product to a variety of customers including Christmas tree growers and operators of golf courses. Prices: up to $20 a ton. The need to mulch disposable diapers exposes P&G's weak flank. Says Richard Denison, senior scientist at the Environmental Defense Fund in Washington, D.C.: ''What makes these diapers appealing in the first place is that you don't have to think about putting them in a special bin and taking them ) somewhere. You just throw them out.'' Disposable diehards couldn't agree more.