On the other hand, many conservative Republicans also opposed the bill because it didn't cut spending enough. Squeezed on both sides, the bill failed after House Speaker John Boehner brought it up for a vote.
So what happens next? The White House, recall, had already threatened to veto the House farm bill because of its cuts to food-stamp programs. So it likely wasn't going to become law anyway. But if the House bill had passed, Republicans could have at least gone to conference and tried to reconcile it with the $955 billion Senate version, which contained far lighter cuts to food-stamps funding.
So now House Republicans will either have to start over — or, possibly, go to conference without a bill and try to negotiate something with the Senate. (Update: As Deron Lovaas reminds me, this is basically what happened when the House failed to pass a highway bill last year. House lawmakers would still have to approve whatever bill comes out of conference, however.)
And what if Congress can't pass any farm bill at all? In theory, the country would eventually revert to the agricultural rules written back in 1949, when the last permanent farm bill was enacted (subsequent bills have all been temporary). That 1949 act was crafted for a very different United States, with smaller crop production and higher consumer prices. So, for instance, dairy prices would skyrocket once outdated price supports came back into effect.
Not everything would revert, though: Other programs, such as food stamps and crop insurance, would continue indefinitely without changes, since those are permanent programs.
There was a real possibility of a lapse last fall, when Congress failed to agree on a new farm bill in 2012. (Here's a primer on all the weird things that were poised to happen.) Back then, Congress temporarily sustained most of the existing farm programs for another year through continuing resolutions and the fiscal-cliff deal. This time around, either Boehner figures out how to pass a farm bill, or lawmakers will need to start looking at temporary fixes. Or we party like it's 1949.
-- Here's what happens when the farm bill expires and we revert to 1949 law.