Blake Sanden is celebrated in the California almond industry as being the man who convinced growers in the Southern San Joaquin Valley that they were underwatering their trees – and losing production because of it.
It may seem crazy that what is now common knowledge – applying more water can increase yields and reduce the amount of water per pound of almonds – was once a controversial idea, but persuading longtime growers that their trees were chronically thirsty wasn’t as simple as it sounds. Sanden, who recently was honored with a prestigious award by the California Chapter of the American Society of Agronomy, recalls that he had just gotten out of grad school at UC Davis in 1988. He had been hired as the irrigation manager for Paramount Farming, which had acquired almond orchards in southwest Kings and northwest Kern counties. Sanden’s job was to schedule irrigations and do system evaluations on 26,000 acres of almonds, pistachios, olives, grain and cotton.
At the time, the average yield statewide for almonds was about 1,300 pounds per acre. But in the arid Southern San Joaquin Valley, yields often were less than that and Sanden thought he knew why.
“By mid-May, my soil probing is telling me I am already losing significant soil moisture storage that is not being replaced by irrigation and by the time we hit irrigation cutoff for harvest we would have major defoliation,” Sanden recalled. “I had a serious conversation with the ranch managers (who are basically plant and equipment guys) to reveal my findings and I told them I want to increase the normal irrigation depth by 15%, but since they are the ‘almond experts’ and I’m just the soil and water guy fresh out of UC Davis graduate school, what do they think?
“Their response (and this is a literal quote as best as I can remember): ‘You dumb water boy, almonds defoliate naturally during harvest!’ Duh, any tree defoliates ‘naturally’ when it runs out of water.”
That experience left an impression on Sanden, who four years later became the UC Extension Soils, Water and Agronomy Farm Advisor for Kern County. Until his retirement in 2018, Sanden “was the backbone of the UCCE soils and water program in the Southern San Joaquin Valley,” praised Bob Beede, a longtime colleague of Sanden’s in Kern County.
During his career, Sanden was intimately involved in water- and soil-related projects not just in almonds, but pistachios, alfalfa and other crops. He helped introduce microirrigation systems into orchards. He participated in multi-year research efforts that led to the creation of nitrogen guidelines for almonds. He worked on projects involving root stocks, especially those that would help pistachio trees thrive in the salty soils in the Southern San Joaquin Valley.
But the lessons learned from that dusty summer in 1988 never left Sanden. He remained curious about the water needs of various crops in his region. So, he helped install a network of soil moisture sensors in 145 fields covering more than 12,000 acres belonging to 33 different growers representing 14 different crops. From 2002 to 2013, Sanden and his team collected data measuring water use efficiency in those plants.
For almonds, the results from 2002 to 2005 showed that – just as Sanden had sensed years before – trees in the Southern San Joaquin Valley were chronically underwatered. Whereas trees in rainier, cooler parts of the San Joaquin and Sacramento valleys were fine with 42 inches of water per irrigation season, trees in the hotter, drier south needed as much as 50 inches to produce at an optimal rate.
The result of Sanden’s findings? Many growers started to put more water on their trees. And average Kern County almond yields increased by 65% between 2002 and 2011 compared to the previous 15 years.
