CALIFORNIA, United States (AP) — Farmworkers in the nation’s largest agricultural state will be entitled to the same overtime pay as most other hourly workers under a law that California Governor Jerry Brown said Monday that he had signed.

The new law, which will be phased in beginning in 2019, is the first of its kind in the nation to end the 80-year-old practice of applying separate labour rules to agricultural labourers.

California employers currently must pay time-and-a half to farmworkers after 10 hours in a day or 60 hours in a week — longer than the overtime pay for other workers who get it after eight hours a day or 40 hours a week.

AB1066 will gradually lower the number of hours that irrigators, ranch hands and people who tend crops must work before accruing additional compensation. It will take full effect in 2022 for most businesses and in 2025 for farms with 25 or fewer employees.

“The hundreds of thousands of men and women who work in California’s fields, dairies and ranches feed the world and anchor our economy,” Assemblywoman Lorena Gonzalez, D-San Diego, the author of the bill, said in a statement. “They will finally be treated equally under the law.”

Brown, a Democrat, signed the bill following a push by the United Farm Workers union and its allies, who say exempting farmworkers from labour laws is racist and unfair.

The governor, who signed historic legislation granting farmworkers the right to unionise when he was governor in 1975, has declined to comment on the legislation all year and declined again Monday through spokeswoman Deborah Hoffman.

Opponents argued the seasonal nature of farm labour, with long hours crucial to sow and harvest during specific weather and growing periods, does not lend itself to overtime.

They said the legislation would raise costs for farmers and make it more difficult for them to compete with rivals in other states and countries, and that added costs would force employers to cut workers’ hours, ultimately hurting hundreds of thousands of people in California.

The obligation to care for animals “doesn’t always adhere to an eight-hour day, 40-hour work week,” said Justin Oldfield, vice president of government relations for the California Cattlemen’s Association.

Producers can’t afford to pay workers overtime for 60-hour weeks and stay competitive, he said.

They are likely to hire more employees rather than pay overtime, he said, and that would essentially mean a pay cut for existing employees.

Assemblyman Devon Mathis, R-Visalia, called the new law “a slap in the face” that will deprive farmworkers of needed income.

“Sometimes, the best intentions can have the worst consequences,” he said in a written statement.

Farmworkers have been exempt from overtime pay requirements since Congress approved the Fair Labour Standards Act in 1938 to outline workplace protections.

Farmworkers were again exempted in 1999 when California guaranteed overtime pay after eight hours in a day, not just 40 in a week.

California has for decades been a battleground over farmworker rights. Cesar Chavez brought together farmworkers and founded the UFW in the Central Valley in the 1960s, organising thousands of workers who demanded better wages and working conditions.

California was the first state to give farmworkers collective bargaining rights, workers compensation and unemployment service. The state also requires that employers provide rest breaks and access to water and shade.

Brown also announced Monday that he had signed SB1015 by Sen Connie Leyva, D-Chino, permanently extending what had been a temporary 2013 law requiring employers to pay domestic workers such as nannies, caregivers and housekeepers time-and-a-half if they work more than nine hours in a day or more than 45 hours in a week.