Precision Problem-Solving Out West

Precision agriculture may not have caught on as quickly in California as it has in other parts of the U.S. because the growing of fruits, vegetables, and other specialty crops is done on a generally smaller scale than grains, but now it is quickly becoming entrenched. “They used to come out and make rows for us,” John Diener, a San Joaquin Valley grower, says of retailer Western Farm Service. “Now they do that — in a more timely fashion because they can run at night — and they do variable-rate application.”


Tony Oliveira, the operations supervisor for the Five Points, CA, office of Western Farm Service that Diener uses, agrees that farming in this area southwest of Fresno, one of the richest agricultural regions in the world, has changed dramatically in the past four years since the first global positioning system (GPS) units were used. Prior to that, he often could only run the tractors used to prepare the beds for planting for four or five hours a day. They had to stop at night, of course, but even in the morning the thick Tule fog often hampered visibility and made “listing” impossible. “Sometimes it got to the point where the fog wouldn’t clear up at all and we just wouldn’t move,” says Oliveira, shaking his head at the memory.

Today Oliveira keeps five AutoFarm GPS units — mounted on Caterpillar Challengers of various horsepower — busy 24 hours a day, seven days a week, from September through November. It is then that the soil beds must be listed, before the winter rains hit the Golden State and make the ground too wet to work.

This year a $14,000 variable-rate unit has been added to one tractor, allowing for the precision application of fertilizer. And just as it was with GPS, Oliveira is starting to find it difficult to believe how he and his grower-customers ever got along without it.


“This variable-rate is the coming thing because it allows for the right amount of fertilizer in the right spot, based on a grid soil analysis, for whatever crop the grower’s going into” he says. “The bottom line is this will help him increase his yields.”

Hold The Salt

Being able to vary the amount of fertilizer according to the needs of various crops is crucial for a grower like Diener, whose Red Rock Ranch is extraordinarily diversified. But beyond that, Diener is taking the use of precision agriculture to levels previously unexplored in the region.

The San Joaquin Valley’s West Side, as it’s commonly known, may be a rich agricultural region, but it is plagued by water and drainage problems. That in turn has led to the buildup of selenium, boron, and — most importantly — salt; the problem has gotten so bad that some land is no longer suitable for farming. But, with the help of precision agriculture, Diener is taking the land back.

“We took ground that wouldn’t grow anything, the salinity was so high, and we’re reclaiming it,” he says, pointing to a field of alfalfa. “This field is now 300% to 400% better than it used to be, because we’ve leached the salts out.”

The benefits can be enormous. Driving along one of the West Side’s dusty roads, Diener points out some cotton that is being grown in salty soil that looks awful. The grower will be lucky to get a yield of just one bale an acre.

Not far down the road are some much nicer looking fields that Diener says should net three bales an acre. “Same variety (Pima), same farmer,” says Diener with a sigh. “Holes in field put holes in wallet.”

Diener is desalinating his ranch through tiling, the installation of tubes that push water through the soil. With enough water and enough time, the soil is leached of salt and can successfully be farmed again.

Tiling isn’t cheap, however; installing just a half-mile’s worth costs $5,000. At that price, it’s crucial to use a GPS unit in combination with an instrument that measures soil electrical conductivity, essentially mapping the soil salinity in a given region.

Dr. Florence Cassel-Sharmasarkar, a soil and water scientist at the Center for Irrigation Technology, California State University-Fresno, has been mapping Red Rock Ranch for the past couple years. Her work is part of a study for a CalFed program, a partnership aimed at solving water and drainage problems in the state, and especially the West Side. Right now, the benefits are difficult to project. “It’s new technology,” she says. “We’re just at the research level.”

But Diener says that it doesn’t seem like that long ago that applying GPS to farming was at the “research Level.” And perhaps it won’t be long before soil salinity mapping is just another of the services that California PCAs will provide to their grower-customers.

“The issue is ‘How do you integrate this technology into farming?'” says Diener, who then answered his own question: “It may be better to hire someone — hire expertise and equipment — that way you can leverage the technology.”

Editor’s note: This article first appeared in the December 2003 issue of PrecisionAg Special Reports.

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