Six years ago, Illinois farmer John Ackerman didn’t hire any contract workers at all. Now he typically hires about 22 every year through a local coordinator that helps farmers hire crews of agriculturally skilled, often Latino workers. Those teams hand-weed the soybeans Ackerman grows alongside the pumpkin and corn crops he uses for his primarily fall-focused agrotourism outfit.

He still hires about the same number of locals, around 25 part-time workers in the fall, many of them teenagers or young adults, to run sales and pick pumpkins. He enjoys mentoring young people, but says it’s felt harder lately to justify hiring inexperienced workers when contract workers do the same hard, physical jobs faster and better.

A higher proportion of U.S. farms are now using contract workers, according to the most recent U.S. agricultural census data, out last month with a five-year update from the previous 2017 data. Because of the terms of their employment, those laborers have specific challenges voicing concerns about their working conditions, and are more likely to be on the front lines of climate change, facing increasing heat and extreme weather.

The U.S. Department of Agriculture defines contract labor as including contractors, crew leaders, cooperatives or any other organization hired to furnish a crew to do a job for one or more agricultural operations. The USDA data showed an uptick in the number of farms using migrant labor, both within farms that already hired contract workers and overall.

Contract workers hired by an agency may work hundreds of miles from where they live, and may move from place to place, making it harder to keep farmers accountable for labor abuses, explained Alexis Guild, vice president of strategy and programs at the nonprofit Farmworker Justice. Some contracting agencies also employ undocumented workers, who may remain silent for fear of being deported. And though some steps are being taken at the federal level to protect migrant workers with H-2A visas for seasonal farm jobs, those regulations have vocal opponents.

Since the immigration status of many H-2A workers is tied to a single job, they may feel less able to voice concerns about their workplaces, added Rebecca Young, director of programs at Farmworker Justice. She said these workers can be isolated from their communities due to language barriers and living arrangements.

Resources like health care and counseling can be out of reach.

Some states have patchwork heat regulations in place for farmworkers, but there are no federal rules about heat exposure. And making a formal complaint can be fraught, though it’s a legal right, said Abigail Kerfoot, senior staff attorney at Centro de los Derechos del Migrante, a nonprofit organization providing assistance to farmworkers.

“Most workers, particularly migrant workers on temporary visas, find it, unfortunately, a difficult decision to make,” she said.

Some farmers see little interest from local workers in the jobs they post.

Jed Clark, a Kentucky grain farmer, said in the 20 years he’s hired H-2A workers, only about 10 locals total have ever shown up to inquire about a job.

“The number of people that want to farm for a living actively is going down. And with the farms growing larger and larger, we’re going to have to have help to operate,” he said.

Reforming the H-2A program is a priority for many farmers, but while they wait for that to happen, many are having to decide whether to switch to less labor-intensive crops or try to mechanize their operations, said Stephanie McBath, director of public policy for the National Association of State Departments of Agriculture.

But for many crops, that isn’t possible: USDA research shows that demand for H-2A workers boomed in 2010-19 in sectors like fruit and vegetable production, which require hand labor that isn’t easily mechanized.