American farmers, fretting over a shortage of workers as immigrant labor becomes harder to find, are being pushed to give mechanization greater consideration.
Even as thousands of Mexican workers push through turnstiles at the San Luis, Ariz., border station to pick winter lettuce crops in Yuma, Ariz., farmers still don't have a sufficient workforce.
"Not a lot of people realize it but on an average day during this time of the year this port processes between 25,000 and 30,000 people a day," says port director William Brooks.
Once past the border agents, workers walk to waiting buses or pick up day work in front of a local convenience store.
Labor contractor Jose Campos, who is at the convenience store grabbing a quick cup of coffee, says despite being so close to Mexico he can't find enough workers.
"It's a big problem. To properly work a lettuce harvester you need 26 guys, I've only been able to bring them eight or nine," says Campos.
Economists say farmers should stop complaining and find machines to do the work.
But lettuce worker Jesus Mitra scoffs at the idea.
"You want a machine to do this instead of a person. There's no such thing, it hasn't been invented yet," Mitra says. "You have to have a person do it."
Or do you?
Agricultural economist Philip Martin doesn't think so. He says when labor is tight, wages rise and that pushes farmers to invest in mechanization.
"We certainly saw that in the 1970s when unions pushed up wages. That was a real decade of mechanization," says Martin.
But by the 1980s, he recalls, the Mexico peso plunged, labor was once again abundant and sanctions against employers hiring illegal workers were minimal.
"By not enforcing the immigration laws the government is sending a signal to farmers that by hiring unauthorized workers they do not have to make a transition to a more mechanized, higher productive agriculture — at least not right now," adds Martin.
But Manuel Cunha, who heads a farmers' group in Fresno, Calif., says mechanization can't solve all of agriculture's labor woes, especially for farmers who grow perishable crops like strawberries and tree fruits.
"If we don't care about how a fresh peach looks or taste that may be a different issue," he says.
Cunha wants Congress to pass the so-called Ag Jobs bill that would create a special guest worker program for agricultural workers.
He recognizes that farmers are mechanizing, but it will take time.
Fresno raisin farmer Trent Hammond isn't waiting for Congress to act.
In his work shed on his family's raisin-grape vineyard, he pulls out huge rolls of paper that will be used to dry the grapes into raisins. Traditionally this is hard work that must be done by hand. In fact, raisins are the most labor intensive crop in North America. It takes 60,000 farm hands to work the four-week harvest in late summer.
Still, Hammond is looking for ways to replace almost all his workers with machines.
On his 43-acre plot he ripped out all of his old vines and is getting ready to plant new ones. These vines will grow straight out of the ground, leaving enough room for a machine to come through the rows.
"We are putting in stakes. We have about 15,000 cross arms, and we still have 28,000 vines we have to put in," he says.
And Hammond says once all the work is done, he will need only three field hands instead of 40.
Martin, the economist, says farmers have to move in that direction if they're going to compete with countries like Turkey and China.
"The ultimate goal is if we are going to have a competitive agriculture 20 years hence we have to compete on something other than wages," he says.
Though he concedes that to do that U.S. agriculture will look a lot different in the next two decades.
It will consist of larger mechanized fields and less small-time family farms.