HURON, Calif. — Farm labor contractors across California -- the nation's biggest agricultural engine -- are anxiously studying a provision of the Affordable Care Act, which will require hundreds of thousands of field workers to be covered by health insurance.

And while the requirement to cover workers was recently delayed until 2015, the contractors, who provide farmers with armies of field workers, say they are already preparing for the potential cost, inconvenience, and liability the new law will bring to their business, which typically operates on a slender profit margin.

"I've been to at least a dozen seminars on the Affordable Care Act since February," said Chuck Herrin, owner of Sunrise Farm Labor, a contractor based here. "If you don't take the right approach, you're wiped out."