Articles
Mild to moderately high thresholds for the start of irrigation in spring reduced yield and achieved minimal water savings in California almonds
Article number
1409_29
Pages
215 – 222
Language
English
Abstract
Total almond exports produced in California are valued at $ 4.6 billion dollars from a crop harvested over half a million ha.
As California water availability is expected to decrease and competition from other irrigated crops increases, it will be critical to reduce the water footprint of almond to ensure sustainable production and profitability.
The objectives of this research were to investigate: the use of stem water potential (SWP) thresholds to determine when to start spring irrigation in commercial almond orchards; and whether delaying irrigation in the spring would reduce water stress later in the season by preventing root damage caused by saturated soil.
Thresholds were designated with reference to a fully irrigated baseline.
Treatments targeted irrigation at baseline SWP (control) and SWP at 0.2 MPa (mild water stress) and 0.4 MPa (moderate water stress) below the baseline, respectively.
Trials were conducted on commercial farms in Stanislaus and Tehama counties in California during 2020 and 2021. Stem water potential, canopy photosynthetic active radiation interception and yield was monitored at different time scales.
In Tehama County, there were trends in less yield and nut load with delay, but with no statistical significance.
In Stanislaus County, there was no significant difference in yield after the first year of delayed start in the irrigation season, but yield was significantly reduced in the second year in the most delayed start time.
For both sites, delays in the start of the irrigation season have reduced the cumulative amount of water applied from 4 to 12% without significantly affecting yield.
Once the first irrigation was applied and regular irrigation resumed, it often took several irrigation cycles before delayed irrigation SWP dynamics were similar to the control and there was some evidence of extended tree water stress due to the delayed start of irrigation, especially in the most delayed treatments.
The period of delay, ranging from 7 to 15 days, and potential for water savings has been minimal, especially compared to walnut.
As California water availability is expected to decrease and competition from other irrigated crops increases, it will be critical to reduce the water footprint of almond to ensure sustainable production and profitability.
The objectives of this research were to investigate: the use of stem water potential (SWP) thresholds to determine when to start spring irrigation in commercial almond orchards; and whether delaying irrigation in the spring would reduce water stress later in the season by preventing root damage caused by saturated soil.
Thresholds were designated with reference to a fully irrigated baseline.
Treatments targeted irrigation at baseline SWP (control) and SWP at 0.2 MPa (mild water stress) and 0.4 MPa (moderate water stress) below the baseline, respectively.
Trials were conducted on commercial farms in Stanislaus and Tehama counties in California during 2020 and 2021. Stem water potential, canopy photosynthetic active radiation interception and yield was monitored at different time scales.
In Tehama County, there were trends in less yield and nut load with delay, but with no statistical significance.
In Stanislaus County, there was no significant difference in yield after the first year of delayed start in the irrigation season, but yield was significantly reduced in the second year in the most delayed start time.
For both sites, delays in the start of the irrigation season have reduced the cumulative amount of water applied from 4 to 12% without significantly affecting yield.
Once the first irrigation was applied and regular irrigation resumed, it often took several irrigation cycles before delayed irrigation SWP dynamics were similar to the control and there was some evidence of extended tree water stress due to the delayed start of irrigation, especially in the most delayed treatments.
The period of delay, ranging from 7 to 15 days, and potential for water savings has been minimal, especially compared to walnut.
Authors
C. Reyes, L. Milliron, R. Duncan, J. Vasquez-Mendoza, A. Fulton, K. Shackel
Keywords
SWP, pressure chamber, baseline, early season, water management, water stress
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