Almond growers today use 33 percent less water to produce a pound of almonds than they did 20 years ago.
The use of improved monitoring techniques to schedule irrigation based on soil moisture, tree needs, and climate deserves much of the credit for the improvement.
About 80 percent of almond growers use different demand-based monitoring technologies to schedule irrigation rather than irrigating on a predetermined schedule.
These include a combination of:
- Tracking weather conditions and using evapotranspiration (ET);
- Soil-based monitoring through methods including neutron probes, tensiometers, capacitance and TDR sensors, and the “touch and feel” method; and
- Plant-based methods, including pressure chambers.
Even with advances over the last two decades, growers continue to look at ways to improve and integrate weather/ET and soil and plant monitoring for better, more precise irrigation management and water resource efficiency.
For example, in Manteca, almond grower Nick Gatzman of Travaille and Phippen, Inc. uses electric soil moisture monitors at different depths throughout the soil profile to get real-time data on soil moisture status transmitted to his cell phone every 15 minutes.
This information helps Gatzman decide how long to irrigate to fill the soil profile. He also uses daily calculations of evapotranspiration rates to schedule irrigation for the following week.
Like most growers, Gatzman combines those data points with the experience and knowledge of his orchards to make an educated decision about how often and how long to irrigate.
But Gatzman is also looking at newer technologies to improve to make even better decisions. This year, he is experimenting with remote aerial imaging to isolate areas of stress in orchards. An additional filter on the aerial images provides a chlorophyll signature that may allow Gatzman to identify areas of early stress before it visibly appears in the orchard.
While this new technology is still experimental, this type of innovation ideally will allow almond growers in the future to further fine-tune irrigation management with more targeted irrigations for different zones within the orchard block.
The Almond Board of California (ABC) is funding research on precision water management that integrates new approaches to determining tree water status and zone-based irrigation management.
The research has been leveraged with additional funding from the USDA Specialty Crop Research Initiative, and California Department of Food and Agriculture (CDFA) Specialty Crop Block Grant Program.
Continuous plant monitoring
A project spearheaded by Shrini Upadhyaya, Department of Biological and Agriculture Engineering at the university of California, Davis, aims to develop a precision water management system for irrigating almonds and other tree crops.
His research team has developed a continuous monitor that measures leaf temperature and other environmental variables (e.g., light level, air temperature, relative humidity, and wind speed). It also computes a plant water stress index that is correlated with stem water potential, a measure of tree water status.
Moreover, this system can be interfaced to a wireless network, making it possible to obtain the stem water potential information through the Internet or mobile devices at a grower’s fingertips, virtually eliminating the need to measure the plant water status with pressure chambers — a tedious and labor-intensive task.
The leaf monitor technology is available through Cermetek Microelectronics.
The plant water status data obtained through the continuous leaf monitoring system can be integrated with weather/ET and soil moisture information. There is also potential for the integration of data from newly emerging technologies, including aerial imaging, into a wireless mesh network.
Newly developed operating systems ideally will help support irrigation decisions leading to variable-rate precision irrigation management schemes fine-tuned to individual zones in the orchard.
Water at the right time
Pulling all of the pieces together will lead to the application of the right amount of water at the right time and in the right place to most efficiently utilize our water resources.
The ABC, along with others, is currently providing funds to expand Upadhyaya’s research on the precision water management system from a couple of rows to five acres, with a view toward proving its success on a commercial scale.
The expectation is that these newer technologies will make obtaining tree water status simpler and less tedious, plus provide a means of fine-tuning irrigation to account for soil and orchard spatial variability.
This will be a big step toward better production efficiency and enhanced water stewardship.