Pressure chambers help Valley farmers save water during drought

SELMA — Tom Chandler, a fourth-generation farmer, is using a sophisticated suitcase-sized tool to do what farmers used to do largely by guesswork: Size up how much water to give his almond trees.

The device is a pressure chamber, and it squeezes water from leaves to measure how thirsty his trees are.

“Using the pressure chambers is like having a fuel gauge for your plants,” Chandler said.

With the Valley in the third year of a severe drought, farmers are turning more to such devices to help them more carefully calibrate their watering schedules — giving orchards more water some days, less on others.

“Before we started using these, we had no idea when the plants really needed water,” Chandler said. “Now we can figure out exactly when we’re running out.”

Chandler and his family have farmed for more than 100 years and are excited to see the improvements pressure chambers make in their orchards.

“They have helped us save water and we are more confident about what we’re doing,” Chandler said. “We irrigate more frequently but use much less water each time.”

Allan Fulton, an irrigation and water farm adviser, has worked with pressure chambers since 2000. Fulton has conducted research on calibrating what the chamber readings mean.

“Understanding what the chamber is trying to tell you helps farmers concentrate water in the areas that need it the most,” Fulton said. “This means more production while using the same amount of water.”

Fulton said he believes pressure chambers teach farmers one of two things — your crop needs more water, or you could be getting by using less water.

“These are unquestionably helpful in a time like this,” said professor Ken Shackel of the University of California at Davis. “You can save tons of water thanks to the chambers.”

Shackel has heavily influenced pressure chambers through his research. These were invented in the 1960s, but Shackel began studying them in the early 1980s.

“It wasn’t that pressure chambers were my new idea, but no one had ever tested them in the field,” Shackel said. “It was through researching with the plants that we realized dry soil doesn’t mean the plant is suffering.”

Thanks to his research, Shackel was able to create a smaller, simpler model that used less pressure and was portable. This model increased pressure chamber use among farmers.

“I developed a bicycle-pump model that didn’t require a big pressure gauge,” Shackel said. “A lot of farmers are using that model now as opposed to the other one.”

Pressure chambers are manufactured by Plant Moisture Status Instrument Co. in Oregon. The company says they’re used by 25% of California farmers.

“The chamber gives us a way to see our watering patterns from the tree’s point of view,” Chandler said.

Chandler has worked mostly as the financial manager for his parents’ farm. However, he has his own orchards and does much of the work on his farm by himself. This includes going out once or twice a week to check on the almond orchards using pressure chambers.

Typically between 1 and 3 p.m., Chandler will take samples from the trees and test them. He does this by taking a leaf from a tree and placing the stem into a hole in the chamber. Then, pressure is applied to the leaf and water will seep out of the stem.

“It’s important to do the readings around the same time every day,” Chandler said. “The readings are calibrated for that specific time frame.”

Chandler loads his pressure chamber into the back of his ATV and can complete his tasks in about an hour.

“We haven’t been using this technology for long at all,” Chandler said. “But it’s really great to see a difference already being made. Hopefully that progress will just keep getting better and better.”


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