Posts Tagged: David Doll
Because periodic droughts will always be a part of life in California, the UC California Institute for Water Resources (CIWR) produced a series of videos to maintain drought awareness and planning, even in years when water is more abundant.
The first of the three videos premiered Feb. 2 on the UCTV Sustainable California channel. The second video was launched March 2 on Sustainable California. The final video will debut April 6. View the trailer here.
The videos are inspired by a collection of 19 drought tips produced by CIWR in collaboration with UC Agriculture and Natural Resources researchers during the drought of 2010-16. The tips cover a broad spectrum of California crops, from alfalfa to walnuts. Topics also include salt management, use of graywater in urban landscapes, and the use of shallow groundwater for crop production. Three topics – alfalfa, almonds and citrus – are featured in the three-episode CIWR video series.
The drought tips collection and the drought tip videos were sponsored by the California Department of Water Resources. Following is the schedule for the video releases:
The CIWR drought tip series opens with Cannon Michael of Bowles Farming in Los Banos. The alfalfa grower works with UCCE specialist Dan Putnam. “There's a lot of misunderstanding about alfalfa as a crop,” Michael said. “It does take water to grow it, as with anything, but you get multiple harvests of it every year.”
The second episode features almond producer Raj of Meena farms. He works with David Doll, UCCE advisor in Merced County. “One positive of this drought,” Meena said, “is that it has forced us all to be more efficient in how we use our water.”
Friday, April 6: Irrigating citrus with limited water
The series finale features Lisa Brenneis of Churchill-Brenneis Orchard in the Ojai Valley of Ventura County. She worked with UCCE advisor Ben Faber to install a new water-efficient irrigation system. “Irrigation is the only job we really have to do,” Brenneis said, “and we have to get it as right as we can.”
For a complete list of drought tips, see http://ucanr.edu/drought-tips.
Research by UC Davis and UC Agriculture and Natural Resources scientists found that almonds have a relatively small carbon footprint, which could be further reduced with advanced management practices.
Two related articles published in the current issue of Journal of Industrial Ecology examine the environmental impact of this agricultural industry. Co-author Alissa Kendall, an associate professor in the UC Davis Department of Civil and Environmental Engineering, and her colleagues noted that certain practices substantially reduce greenhouse gas emissions and energy use, including the strategic use of co-products, and the choice of water source and irrigation technology.
"Our research shows that 1 kilogram of California almonds typically produces less than 1 kilogram of CO2-equivalent emissions, which is a lower carbon footprint than many other nutrient- and energy-dense foods," said Kendall.
“These results include the use of almond co-products — orchard biomass, hulls and shells — for renewable power generation and dairy feed,” said Kendall. “Under ideal circumstances, which are feasible but not in place today, California almonds could become carbon-neutral or even carbon-negative, largely through the improved utilization of orchard biomass."
David Doll, UC ANR Cooperative Extension advisor in Merced County, agrees.
“As California farmers improve their nitrogen and water use efficiencies, they will reduce the carbon footprint,” Doll said. “This will happen as we continue to transition into a nitrogen budgeting system, which will reduce over-applications of nitrogen. Furthermore, on the other end, research conducted by Cooperative Extension has shown that the entire biomass of an orchard can be incorporated back into the soil, which increases the amount of total carbon sequestered.”
“Only a full life cycle-based model like the one we developed for this research will allow us to accurately assess whether incorporating the biomass into the soil or using it for power generation instead results in a lower net carbon footprint,” said Sonja Brodt, academic coordinator in the UC ANR Sustainable Agriculture Research and Education Program, noting that there will be some trade-off.
The first article, "Life Cycle-based Assessment of Energy Use and Greenhouse Gas Emissions in Almond Production, Part I: Analytical Framework and Baseline Results," is authored by Kendall, Elias Marvinney, a graduate student in the UC Davis Department of Plant Sciences; Brodt and Weiyuan Zhu, a UC Davis graduate student in horticulture and agronomy.
Marvinney is lead author of the second article, "Life Cycle-based Assessment of Energy Use and Greenhouse Gas Emissions in Almond Production, Part II: Uncertainty Analysis through Sensitivity Analysis and Scenario Testing," in collaboration with Kendall and Brodt.
This research was supported by grants from the Almond Board of California and the CDFA Specialty Crop Block Grant Program.
Brodt and Marvinney will host a webinar to discuss their life cycle assessment analyzing the environmental impacts associated with walnuts, prunes, peaches, almonds and pistachios. The researchers are quantifying energy use and greenhouse gas emissions in orchard crop production both within and beyond the farm. To join the webinar, visit https://uc-d.adobeconnect.com/orchard-lca at noon on Wednesday, July 29.
The University of California Global Food Initiative aims to put the world on a path to sustainably and nutritiously feed itself. By building on existing efforts and creating new collaborations among UC's 10 campuses, affiliated national laboratories and the Division of Agriculture and Natural Resources, the initiative will develop and export solutions for food security, health and sustainability throughout California, the United States and the world.
David Doll. “You don't notice it until it's too late, and that's when we have a problem,” he said.
Saline accumulation in the orchard soil profile is a recurring headache. But it becomes more acute during droughts, when farmers use more groundwater – which is generally more saline than surface water – or their surface water supply is more saline than normal.
Salinity accumulates in the soil when the tree is growing quickly and almonds are developing throughout spring and summer. When water with dissolved salts is applied, the roots of the tree will exclude the salt, sucking up only water. As salt accumulates from successive irrigations, the tree must work harder to pull up water. The extra stress slows growth and yields drop.
“At this stage, the trees look healthy, but they're not reaching their full potential,” Doll said.
In time, however, salt can accumulate to toxic levels and the tree will no longer exclude the salt.
“The salt toxicity becomes apparent in older leaves, which turn brown along the margins, and eventually fall off the tree,” Doll said. “We saw quite a bit of this in Merced County this year, especially on sandier soils.”
The cure? More water. Winter rain can help leach salt out of the root zone. If California experiences another dry winter, farmers will have to apply groundwater to flush salt away from almond tree roots.
“Seventy-five percent of our almond orchards are OK when there is enough rain,” Doll said, “but some farmers must apply water in the winter even in normal years.”
Doll recommends farmers sample their soils in the fall at various depths to assess salinity in the root zone.
To wash out accumulated salts, enough water must be applied to fill the soil profile, he said. Once the profile is full, smaller quantities of water applied either through rain or irrigation will move salts below the root zone.
An initiative to improve California water quality, quantity and security is part of the UC Division of Agriculture and Natural Resources Strategic Vision 2025.