Ron Gayler, a staff technician at the University of Arizona's Yuma Agricultural Center, works on a prototype of an automated crop thinner. RANDY HOEFT / YUMA SUN

YUMA - The search is on for new agricultural technology, with the University of Arizona's help. It's a search driven by looming labor shortages as the aging farmworker population retires and younger people aren't following them into the fields.

"The trend we're seeing in the next 10 years is alarming," said Kurt Nolte, director of the Yuma County Cooperative Extension. "The number of new workers is markedly less. We're looking to alleviate that with mechanization."

Mark Siemens, an ag mechanization specialist with the University of Arizona's Yuma Agricultural Center, agrees. He sees new technology not so much displacing workers as freeing up people for other tasks where the human factor is still needed.

A case in point is Yuma County's high-value winter vegetable industry, where thousands of workers labor in the fields at the height of the season. Citrus and melons also remain labor-intensive crops.

"We still need people to plant, thin, weed, irrigate and harvest the crops," Nolte said. "There's still a heavy demand for fieldworkers. The human factor is so valuable. The human eye, touch and feel can't be replaced now."

He estimates that about 50,000 workers are needed in Yuma-area fields, coolers and salad plants at the peak of the winter vegetable and citrus production.

There have been mechanical advances to make their workloads easier and to reduce the need for workers, Nolte said.

One of the more notable advances in recent years is the mechanical harvester used for baby lettuce leaf mixes, he said. The machine, which in some ways resembles a huge mower, works for that crop because the entire field is cut at the same time, and there is no need for a selective process for a perfectly shaped head of lettuce.

One machine with five operators can do the work formerly done by 50 workers wielding a sickle-like hand tool, Nolte said. "Within a five-year span, we've come from hand harvest to total mechanization of the baby leaf crop."

The machines seen in fields where head lettuce is harvested are an example of technology that has made life a little easier for fieldworkers, he said. The cutters now put the cut and wrapped heads on the machine for packing, which are then delivered to trucks for transporting, instead of having to come back through a field and pick up the heads manually.

The advances of tomorrow will have a major impact on agriculture - things such as robotics, plant-sensing machines to thin and weed fields, and continuing GPS applications, said the UA's Siemens.

One project he's been working on, in cooperation with Pasquinelli Produce, is a mechanical thinner that uses a computerized sensor to detect the lettuce plants and selectively remove them from a row. Funded through a specialty crop grant from the Arizona Department of Agriculture, Siemens built a prototype and is now working on modifications and testing.

He said the machine is something growers have asked for, because thinning is a time-consuming and expensive task, one that for the workers is tedious and difficult.