Under pressure because of their thirsty crop, almond growers have actually been working to save water for a long time. Now the Almond Board of California is offering a new manual to help them conserve in progressive steps.
By Matt Weiser
Almonds are big business in California, generating $5.3 billion in revenue for farmers in 2015. They are the state’s second-largest farm product after dairy. But almonds also consume a lot of water.
The almond-growing industry has been under scrutiny for its water use since the state’s drought took hold. In part, this scrutiny arose because farmers have converted thousands of acres of agricultural land from annual row crops to lucrative almonds, a permanent crop that requires water year-round.
Numerous media reports have noted, for instance, that around 1 gallon [3.75 liters] of water is required to produce a single almond. Total California acreage planted with almonds has grown about 35 percent over the past decade, resulting in a significant new permanent water demand.
Growers are listening to these concerns. Led by the Almond Board of California, they are installing drip irrigation and micro-sprinklers, and measuring water demand more carefully with evapotranspiration sensors and other devices.
Now the Almond Board has produced a water-management guide for growers. Called the Almond Irrigation Improvement Continuum, it lays out four tiers of irrigation progress for growers, from easy to advanced. To learn more, Water Deeply interviewed Spencer Cooper, senior manager of irrigation and water efficiency for the Almond Board.
Water Deeply: What is unique about irrigating almonds?
One thing that is unique about irrigating almonds is the importance of continuing to provide the trees with water through October, even after the crop has been harvested. This time period is when flower buds that will bloom the following year are developing, and, thus, the trees need water and photosynthesis to power the process. Failure to do so reduces the number of blossoms available for pollination, decreasing the overall crop potential of the orchard.
Water Deeply: Are there particular aspects of irrigating almonds that growers find challenging?
Cooper: Based on location, irrigation system design, water availability and more, each almond grower deals with a unique set of challenges – some of which are out of their control.
For instance, almond growers who depend on irrigation districts for their water are often challenged by the delivery schedule and mechanism of those districts – tactics that were designed decades ago for flood irrigation.
Over 70 percent of California’s almond growers use micro-irrigation systems, which rely on pressurized, on-demand water, something most irrigation districts don’t offer. Growers thus have to devote some of their land to holding ponds, where they can locally store and pressurize water for precisely when their trees need it. This is in contrast to the weekly or biweekly water delivery schedules employed by irrigation districts to deliver water through gravity-fed, unpressurized canals.
Another challenge in recent years has been lack of water availability due to ongoing drought. While winter rains may currently be refilling our reservoirs and the Sierra Nevada snowpack, almond growers remain committed to precision irrigation and growing more crop per drop.
Water Deeply: What exactly is the Almond Irrigation Improvement Continuum you recently made available to growers?
Cooper: The purpose is to accelerate grower adoption of research-based, commercially available and more water-efficient irrigation management and scheduling tools. This guide encourages continued improvement in a grower’s irrigation management strategies, addressing five essential elements.
Those five key areas include: estimating orchard water requirements based on evapotranspiration; measuring irrigation system performance and efficiency; determining the water applied; evaluating soil moisture; and evaluating plant water status.
The continuum has something to offer every almond grower, regardless of their irrigation management sophistication, and the entry-level management guidelines require zero capital investment. It re-establishes a foundation of irrigation management in touch with today’s farming conditions, and provides growers with the knowledge and tools to improve from there.
Beyond its utility for California’s almond growers, the continuum will likely offer a model for improving irrigation in other California fruit and nut tree crops.
Water Deeply: To what extent do its recommendations rely on new technology (sensors, irrigation methods, etc.) or did you try to avoid that?
Cooper: The continuum has something to offer every almond grower, regardless of their irrigation management sophistication. The ultimate goal is to educate farmers, and each level is written in a way that is informative and actionable.
Because of its three levels of guidelines, growers will find a management style that fits their local conditions, with tips for advancing to the next level. The highest level of the continuum does offer guidance for integrating newer technologies into their irrigation systems.
Thanks to a recognition of the importance of these new irrigation technologies, cost-share opportunities for almond growers and other farmers in California abound. The Natural Resources Conservation Services’ Environmental Quality Incentives Program and the State Water Efficiency and Enhancement Program (SWEEP) at the California Department of Food and Agriculture both provide funding to farmers looking to install cutting-edge irrigation technology. In fact, in 2016 more than 30 almond growers were awarded funds through the SWEEP program.
Water Deeply: What is the water-saving potential of its methods and how difficult is this to achieve?
Cooper: The water-saving potential of any new irrigation technology depends on the irrigation system’s starting point. For instance, switching from flood irrigation to micro-irrigation will have large associated water savings, while moving from a manual measure of soil moisture to an automated system will have a less drastic impact.
The goal of any good irrigation management strategy should be more crop per drop, rather than strictly reducing water applied. Almond trees, like all plants, need a set amount of water to thrive and produce a crop. By meeting that demand, growers set the stage for optimal yields, which allows them to further invest in cutting-edge irrigation technology.
Water Deeply: It has been widely reported that around 1 gallon of water is required to produce a single almond. Is this accurate?
Cooper: The jury is still out on how much water it takes to grow a single almond. The 1-gallon-per-almond statistic you mention is based on specific water footprint methodology using almond yield data averaged across all almond production regions and global climate data. In reality, California is the most productive almond farming region in the world, thanks to the ideal climate, rich soil and efficient growing practices.
In reality, there are many different ways to calculate the water needed to grow food, and none of the current models account for putting a crop’s co-products to beneficial use rather than being sent to landfill. For example, almond trees actually grow three products – all of which are used. These include the almond kernels we love to eat, the hulls that are used as livestock feed – reducing the amount of water used to grow other feed crops – and the shells that are used as livestock bedding.
Water Deeply: Do all growers measure evapotranspiration as part of their irrigation practices or will this be new to many? How difficult is this?
Cooper: Through the California Almond Sustainability Program, we know that 83 percent of almond orchards are managed using some combination of evapotranspiration, soil moisture and the trees’ needs (plant water status) to determine a demand-based irrigation strategy. While this doesn’t answer exactly how many growers use evapotranspiration, it reflects the fact that scheduling irrigations based on evapotranspiration is nothing new to the California almond industry and used by many to inform their water management throughout the growing season.
Growers can easily access local real-time evapotranspiration data through the Department of Water Resources’ California Irrigation Management Information System (CIMIS). Those numbers are then translated into something meaningful for almonds using a crop-specific coefficient. Guidelines on how to do this are found in a variety of resources, including the continuum.
Water Deeply: The continuum notes that “moderate water stress” can be good for almonds. How is this done?
Cooper: This “moderate water stress” refers to a practice that is dual-part integrated pest management and irrigation strategy. As almond trees approach harvest and hulls begin to split, growers can choose to practice what we call “hull-split strategic deficit irrigation,” reducing the amount of water applied by up to 50 percent for a limited time during the summer. During this particular period of the growing season, the tree is less sensitive to water stress without negatively impacting current or future crops.
The primary reason for this practice is to control hull rot, a fungal disease that can kill the woody shoots the infected nuts are growing on and cause dieback of the tree’s fruiting branches. But it has the added benefit of reducing water requirements at the height of summer. In fact, during the drought, this strategy was employed by almond growers who received less than adequate water for their orchards.
Water Deeply: Another goal of the continuum is to get growers to do more real-time monitoring and to adjust their irrigation in response. Why is this important?
Cooper: Increasing the frequency at which growers monitor local conditions allows them to manage their irrigation scheduling adaptively, increasing precision and decreasing inefficiencies. Using real-time monitoring gives growers a more accurate picture of what is going on within their orchard, allowing them to be more proactive in their management decisions.
As a research-based industry, users of limited water resources and stewards of some of the world’s most productive farmland, all almond growers should strive for continuous improvement – be it in irrigation management or beyond. No matter where their starting point, every California almond grower will be able to learn something and evolve their practices through the continuum.
- Originally appeared at Newsdeeply.com