Huckaby supervises the six Trimble AgGPS Autopilot systems used across the Bakersfield, Calif., company’s dispersed operations, from Kern County to Colorado, the coast, the Imperial Valley and Yuma. Carrot production occupies 35,000 acres each year.

Capable of penetrating darkness, fog, or dust, the guidance equipment, he says, guarantees listing accurate to within a half-inch for the greatest efficiency and economy.

Grimmway, which also farms potatoes, spinach, broccoli, and various other vegetables in both conventional and organic methods, expects the Trimble guidance equipment in time will offer other advantages.

Listing top priority

"Listing is priority one of the equipment, or about 95 percent of the time," Huckaby says, "because that’s where we recoup our costs the most. We can also disk, or plow, or plant wheat with it. Any implement we can fit on the tractor we can use with it, and when we’re applying a chemical or fertilizer, the more precision we have, the less waste.

"We are moving into the other uses on a small scale at first, and units for planting and cultivating will be the next step."

A veteran of nearly a dozen years in carrot production, Huckaby has been with Grimmway for the past two years. He coordinated a rigorous, four-month shakedown of Trimble and competitors’ equipment in the field last summer.

The trials sprang from Grimmway’s past association with Precision Farming Enterprises (PFE), whose San Joaquin Valley center is at Earlimart, north of Bakersfield.

"We’ve been doing other things with PFE on GPS mapping and yield monitoring," he said, "so that’s how we were introduced to the GPS systems for tractors. When it came time that we had an interest in the systems, we started talking."

The evaluation began with Huckaby running three GPS-guided tractors: one with Trimble gear and two others with competitors’ products. Five Grimmway farm managers ranked the equipment.

"The main thing with the trials was finding out how well the equipment worked in the field. We also wanted to find out what support services were available," he recalled.

Unanimous decision

"All five of the managers wanted the Trimble unit. It performed the best of the three. Another important reason was the top-notch support we got from PFE. The managers rated it at the top for ease of use.

"PFE came in with Spanish-speaking trainers to go over the systems with our drivers. Any piece of new equipment like this can be intimidating to anyone, but our guys were able to grab hold of it pretty quick."

For tractor drivers, at the wheel for 10 hours a day, six days a week, manually keeping the equipment in a straight line is fatiguing.

The Trimble GPS equipment relieves much of the fatigue, with the driver monitoring a light-bar atop the dashboard of the tractor. It provides a straight-ahead visual reference, rather than through a monitor at one side, for alignment.

"The equipment steers the tractor in a straight line, but the driver still has plenty to do, concentrating on the performance of the tractor and the implement."

The steering is automatic, however the systems have a safety feature that requires the driver to interact with the controls. If for some reason the driver is not able to do the interaction, the controls put the tractor into a wide turn.

Conquering the issue of straight rows means greater productivity from each field. According to Trimble sources, the equipment is accurate to about one-half inch, in contrast to the two to three inches of error common in manually listing, and that increases the number of rows per field. In addition to more rows, the GPS-guided fields are more efficient for irrigation and avoid losses to off-target cultivation equipment.

"We noticed this right away in the trials when we eliminated the crooked rows and the cultivator blight," Huckaby said.

Night vision

But the company was also keen on something else: the equipment "sees" through darkness, fog, or dust, an important advantage when planting or other operations won’t wait until clear, daylight conditions.

"Before, a lot of times, we’d just have to park the equipment. With GPS we don’t need the visibility to get the job done. It cuts our downtime, and we get the best return out of tractors and equipment by operating them all the time."

Grimmway has five Caterpillar Challenger 75E tractors and one John Deere 9300T so equipped. The six units purchased don’t begin to cover all needs, but the tractors are shuttled between ranches to keep them in full operation.

The gear essentially has two major components: the GPS unit that receives guidance via radio from a ground station set up within six miles of the field being worked and the steering mechanism, either hydraulic or electric. The electronic "smart" pieces, those other than the steering controls, can be easily switched from one tractor to another.

Although downtime is held to a minimum, delays may occur, however, due to demands on satellite time and not any malfunction of the equipment. PFE representative Karol Aure Flynn explained that at times too few satellites are accessible or those available are not in the correct geometry for positioning. Customarily, she said, delays are no more than a half-hour and can be predicted so they do not interfere with work schedules. Beyond the benefits of ruler-straight listing, the GPS equipment is also capable of recording survey-grade data.

Flynn said each guidance system represents an investment of about $50,000 and she estimated that 75,000 to 100,000 GPS units of all brands are in use in California.