Yesterday the Washington Post published the last in the series of farm subsidy stories that debuted last June Harvesting Cash: Working a Farm Subsidy.

This installment describes the struggle to place caps on farm subsidies, which are now unlimited because large producers collect unlimited taxpayer payments through loan defaults and commodity certificates.

There may be no better sign of the changing debate over the nation's farm subsidies: A Midwestern governor running for president calls for cuts in a system that has steered hundreds of millions of dollars a year to his state.

"I didn't get much of a reaction from farmers," said Iowa Gov. Tom Vilsack (D), "because deep down most of them know the system needs to be changed."

Politicians such as Vilsack have joined a host of interest groups from across the political spectrum that are pressing for changes in government assistance to agriculture. They want the money moved from large farmers to conservation, nutrition, rural development and energy research. Vilsack, for example, favors programs that improve environmental practices on farms.

In particular, the Post notes how an amendment by Senators Charles "$275,000 is enough" Grassley and Byron Dorgan, which passed overwhelmingly in the Senate in 2002, simply disappeared during the horse trading in the House-Senate Conference Committee. The House version had no comparable amendment, but a non-binding House Motion to Instruct the Conferees, authored by Rep. Ron Kind of Wisconsin, had recommended adoption of the Senate's payment limit and conservation provisions, and had passed overwhelmingly.

Of course, this is a commodity-specific debate that for the most part pits very large-scale rice and cotton farmers who collect huge subsidies, the majority of them in the South, against the rest of agriculture.

Defenders of the status quo are basically arguing that Southern agriculture is entirely unsustainable without perpetually unlimited subsidies to its very largest producers.

That assertion is where the battle lines on payment limits will form in next year's farm bill.