Joy Hollingsworth, a graduate student at Fresno State University, said drip irrigated fields at the center tended to have mites while overhead irrigated fields did not.

But the weed population was greater with overhead, she said. There were no differences in yields between drip and overhead irrigation, but with drip there appeared to be lower chlorophyll levels.

Marvin Wollman, with WHB Farms in Warden, Wash., said a “key driver” in the choice to go to overhead pivots was labor.

“The transition can be challenging,” he admitted. Among the challenges: “You have to learn your soils. You learn by experience.”

His company uses the overhead system to chemigate. “We don’t need to fly or to run sprayers,” Wollman said.

As in the central San Joaquin Valley, he said, rainfall levels are low in the Columbia Basin,, as few as 6 to 9 inches of rain in a year.

“With rainfall that low, we can control water to achieve what we want,” he said.

But, as in the Valley, it’s costly to go deep for needed water. “It’s expensive to drill,” Wollman said.

He proceeded to recount a string of technologies used to keep tabs on his systems, including weather stations that indicate wind speed so that he will know whether he can chemigate on a farm that spans some 70 miles and soil moisture sensors that can be read remotely.

Among his ambitious plans is to put “a Wi-Fi cloud” over the entire farm “to create our own network” for monitoring and managing use of his equipment.

Dan Wilke, with William Bolthouse Farms in Bakersfield, grows carrots with pivot systems that took the place of solid set pipes. He also said there was “a learning curve” for establishing pivot use, but it has proved worthwhile.

“You have to commit to it,” he said.

Among the challenges is the fact that systems may get mired in mud as they circle. One solution: going from two wheels to three or four.

Mitchell said the use of the new farming techniques can hold a key to what farmers must do in the future: “producing more with less. It’s a global imperative.”

He showed plots where low or no-till farming has been done since 1999. He admitted that in the first four or five years, there were lower yields on no-till cotton compared with conventional till.

“But the last five years, there has been no yield loss in cotton,” he said.

Representatives of the Natural Resource Conservation Services showed how to evaluate the chemical, physical and biological properties of soils. The program closed with a presentation by Dennis Chessman, state agronomist with NRCS, who said his staff can help growers making the transition to low or no-till farming.