A SPECIAL GROWERS’ REPORT OF AG ALERT ® C A L I F O R N I A Trees & Vines ®
Pecan farmers test remedies to recharge aquifers Water seeps into an orchard in the San Joaquin Valley as part of test efforts to recharge aquifers with surface water captured during wetter winter months. A pilot program targets California pecan farms. A survey found that pecans were well-equipped to handle saturated soils.
ByDennisPollock Almond farmers in California have long been recharging depleted groundwater sup- pliesonsomeof theirmillionacres.Nownewinsights arebeing learnedas growersof a far smaller sister crop—pecans—are also capturing surfacewater inwintermonths in order to recharge underground aquifers. Pecan farms account for just 5,000 acres inCalifornia. But efforts by farmers to capture rainwater inwetterwintermonths and later flood their farms to reinvigorategroundwater supplies are offering new remedies to severe drought conditions. SandraBachand, co-founder of Bachand&Associates, talkedabout thepecan findings fromapilot researchproject duringa recent virtual presentation. It also includeda talkon the roleof soil textureand flooding innitrate leachingbyHelenDahlke, associateprofessor in integrated hydrologic science at theUniversity of California, Davis. Theprogramendedwithadiscussionbyagrowerpanel that includedoneof theearliest pioneers in on-farm recharge, Don Cameron with Terranova Ranch in Fresno County, who said he believes capturing water for recharge in the winter months “helps tomake Californiawater resilient.” The presentation can be accessed on YouTube under the title “On-Farm Recharge Webinar: Pecans &Other Nuts.” Bachandtalkedof aresearchstudy focusingonon-farmrechargeonfourplotsof pecans paid for byaNatural ResourcesConservationService specialtycropblockgrant from2018 to 2021.
The survey was conducted fromearlyMay tomid-June in 2019 and 2020. It found that pecans were able to tolerate saturated soils and floodingwell. No abnormalities, such as signs of bronzing or wilting, were observed, and there were no differences between trees in on-farm recharge treatments from those in a regularly irrigated treatment. Leaf analysis showed on-farm recharge either improved or had no effect on nutrient levels. Stemwater potential data indicated healthy trees. And yields were the same or higher in on-farm recharge plots compared to the regularly irrigated control and other nearby orchards in 2019 or 2020. Lowoxygenwas not detrimental to pecan tree health and yields. Additional benefits included salt flushing from the root zone and the ability to reduce irrigation. Bachand said recharge projects are being spurred in part by climate change, with less surface water stored in California’s snowpack and greater frequency and variability of drought and floods. Another stimulus is the Sustainable Groundwater Management Act and the fact that on-farmrecharge offers “new” water to help augment groundwater. “Water that currently flows out of an area in awet year can be captured in aquifers and that enhances flexibility,” Bachand said.
See RECHARGE, Page 8
August 11, 2021 Ag Alert 7
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