WASHINGTON — The Senate on Thursday started digging into a mega-bucks farm bill that’s a mixed bag for California.

The state’s fruit and vegetable growers largely like what the bill serves up. The state’s commodity farmers want some changes, though the title card in this year’s subsidy fight still pits the Midwest against the South. Overall, the 1,010-page Senate bill boosts some programs and eliminates others used by California farmers.

“In general, they’re very supportive,” Democratic Sen. Dianne Feinstein said of the state’s farmers in an interview Thursday. “In general, I believe this is a good bill for California ag.”

The key phrase being: In general.

While Feinstein and Democratic Sen. Barbara Boxer joined in a 90-8 vote Thursday morning to end a potential filibuster – and thereby kick off formal debate on the bill – lawmakers and Californians alike want many more refinements. The Senate could haggle over the bill for up to two weeks; already, by early Thursday afternoon, lawmakers had proposed 67 amendments.

Feinstein, for one, is considering an amendment to extend nationwide the state’s tougher hen-house standards. Another senator wants to restore $4.5 billion in food stamp cuts, a potentially meaningful change to some 2 million California families currently receiving aid. The state’s $7 billion-a-year dairy industry is scrambling to revise a dairy assistance proposal that’s tilted toward the Midwest.

“We have to get it right,” Michael Marsh, chief executive officer of the Modesto-based Western United Dairymen, said Thursday. “We’d like to have an insurance program that doesn’t discriminate against us.”

In particular, the California dairy industry wants to change an assistance formula to take account of the state’s higher feed costs.

Still, with most Capitol Hill soil sterilized by toxic partisanship, the farm bill is likely to be one of the few legislative sprouts to survive this year. It’s going to be big. The bill is expected to cost $969 billion if kept intact over the next 10 years. It’s also complicated, requiring balancing acts in which regions matter more than political parties. The final negotiations between the Senate and the House, which has not yet taken up its own version, could easily extend after Election Day into a lame-duck session.

“We have a long way to go, and it’s too early to know exactly what will come out of the Senate,” cautioned Charley Mathews Jr., a Yuba County rice grower and chairman of the California Rice Commission.

Complicating the picture for Californians is the absence of any California Republican on the 45-member House Agriculture Committee, a GOP-run panel that will eventually produce the counterpoint to the Senate bill.

California’s specialty crop producers, who successfully fought their way into the last farm bill, have so far managed to keep many of their prior gains. The Senate’s bill, for instance, includes $200 million over five years for a renewed Specialty Crop Research Initiative. Scientists at the University of California at Davis, in particular, have been successful in harvesting these grants.

In a similar vein, the Senate bill renews a Specialty Crop Block Grant program and boosts funding to $70 million a year. California currently receives nearly $18 million annually from this program, with recent grants aiding projects that range from testing anti-frost wind machines on San Luis Obispo County vineyards to boosting fruit-and-vegetable availability in Sacramento farmers’ markets.

The Market Access Program is likewise continued at $200 million a year. Formerly controversial because of its one-time financial support for big companies like Dole and E&J Gallo, the Market Access Program now mostly flies below the political radar. California agricultural organizations peel off the most dollars, with the California Prune Board, California Table Grape Commission and San Francisco-based Wine Institute among the largest recent beneficiaries.

While delicious for Californians, the specialty crop provisions are relatively small portions of the overall farm bill. Dollar-wise, the biggest spending goes for nutrition programs, including the Supplemental Nutrition Assistance Program many still call food stamps. In California, the program is now officially called CalFresh.

The Senate bill shaves food stamp spending, and imposes new limits like a ban on benefits for big gamblers or Lottery winners. A closely watched and politically sensitive amendment would restore food stamp spending, by reducing crop insurance subsidies.

“Let’s agree it is a worthwhile investment in our future to make sure children do not go hungry in this country,” Sen. Kirsten Gillibrand, D-N.Y., said Wednesday upon introducing her food stamp amendment.

Crop insurance will be at the center of other debate, as well, as the bill replaces direct payments to farmers with more subsidized insurance to cover certain bad times. In California, direct farm payments totaled $148 million in 2010, according to an Environmental Working Group database.

The Senate bill eliminates some programs and consolidates others. For instance, a Wetlands Reserve Program that currently pays California farmers to conserve 12,463 acres and a Grasslands Reserve Program that helps conserve 6,000 acres in California would be combined into something new, with uncertain consequences.