Almond Water Usage & Management

Almonds have gained popularity due to their nutritional benefits and environmental appeal, but water usage and management are vital for sustainable agriculture, especially in regions like California, which produces over 80% of the world’s almonds. The water-intensive cultivation of almonds has raised sustainability concerns. To address this, implementing efficient water management strategies, such as drip irrigation and precision agriculture, is essential for optimizing water use in almond orchards. Furthermore, exploring alternative almond varieties that require less water and investing in research to develop water-saving technologies can significantly enhance the sustainability of almond production.

Water is essential for optimal almond tree growth and yield.
In temperate regions, almonds rely solely on irrigation. Precise water management is crucial, requiring the right amount applied at the right time to prevent under- or overwatering issues.

How much water do almonds need to grow?

Compared to many other horticultural crops, almonds have a relatively high-water demand. In the Mallee region, mature almond trees typically require between 1,200 and 1,500 millimeters (or 12 to 15 megalitres per hectare) of water annually.

Figure 2, adapted from Skewes (2013), illustrates the negative impact of reduced water application on almond yield. The data shows a clear decline in Nonpareil almond yields across multiple properties, management approaches, and consecutive seasons when water is limited.

Almond yield response to water — Riverland and Sunraysia (Source: Managing almond trees with less water – HIN).

What are the factors that determine an almond orchard’s water needs?

The primary factor is the tree’s water consumption through evaporation and transpiration, collectively known as evapotranspiration (ETc). Factors influencing ETc include climate (sunlight, temperature, wind, humidity) and orchard conditions (tree size, health, ground cover, soil moisture). Other water needs include replenishing soil salts and accounting for irrigation system inefficiencies.

Rainfall and soil moisture can contribute to an orchard’s water supply, especially early in the season. However, these sources can be variable and often insufficient to meet total water requirements. To optimize water use, irrigation must supplement these natural water inputs.

Calculating Your Almond Orchard’s Water Needs

Accurately determining your almond orchard’s water needs is essential for efficient irrigation and optimal tree health. Several factors influence water consumption, including climate, soil type, tree age, and desired yield.

Estimating Water Requirements with Evapotranspiration (ETc)

Knowing your almond orchard’s water needs is crucial for efficient irrigation. Evapotranspiration (ETc) is a key metric that combines both water lost through soil evaporation and water transpired by the trees themselves.

Calculating ETc: We can calculate ETc by multiplying two factors:

• Reference Evapotranspiration (ETo): This represents the potential water loss from a standardized reference crop (typically short, green grass) under specific climate conditions.
• Crop Coefficient (Kc): This accounts for the unique water needs of almond trees compared to the reference crop.

Step 1: Finding ETo Data (e.g. California, USA)

Online Resources: Several sources provide ETo data, including:

• California Department of Water Resources CIMIS Network (https://cimis.water.ca.gov/)
• UC Statewide Integrated Pest Management Website
• Local newspapers or irrigation districts (may publish CIMIS data)

Obtaining Crop Coefficient (Kc) for Almonds

• Kc values for almonds vary throughout the growing season and are based on experiments where soil moisture is not limited.
• Resources for Kc data may include:
  • Local extension services
  • Research publications on almond irrigation

Obtaining Crop Coefficient (Kc) for Almonds

Formula and Units: ETc (inches/mm of water) = ETo (inches/mm of water) x Kc

Important Notes:

• ETo Accuracy: While in-orchard weather stations can calculate ETo, accuracy depends on instrument placement. Verify values with the nearest CIMIS station or spatial CIMIS data.
• Kc is Not a Universal Value: Kc accounts for average water needs and may require adjustments based on your specific orchard conditions (e.g., tree age, variety, health; see Table 1).

By utilizing ETc calculations and monitoring your orchard’s specific needs, you can optimize irrigation practices, conserve water, and maximize almond production (e.g. California Almond Industry; see Table 8).

Thirty-year average evapotranspiration reference rates (ETo)1 and almond (ETc)2 for selected CIMIS zones in almond-producing areas of California (Source: Almond Board of California Report – Almond Varieties and Selection;).

Almond Water Management

The severity of water stress impacts on plants, including almond trees, depends primarily on the plant’s growth stage and the frequency of stress events. The following section will detail the potential effects of water stress on almond trees at different growth phases.

Early Season (Bud Break to Fruit Set)

Almond trees, like many deciduous fruit trees, experience a period of dormancy during the winter months. This dormancy is a natural biological process that allows the tree to withstand harsh winter conditions and conserve energy.

The early stages of almond growth, from budburst onwards, are critical for establishing vegetative growth and storing carbohydrates for future harvests. Water stress during this critical phase negatively impacts bud development, flowering, fruit set, and overall tree growth. Consistent irrigation is essential to ensure optimal tree health and yield potential.

Factors Influencing Dormancy Breakup

• Temperature: A period of chilling is necessary to break dormancy. This typically involves exposure to temperatures below a certain threshold for a specific duration.
• Day Length: Increasing day length signals the end of dormancy and the onset of growth.
• Hormones: Plant hormones play a role in regulating dormancy and its break.

Irrigation Strategies for Dormancy Breakup

Proper irrigation is crucial during and after dormancy breakup to support healthy almond tree growth and development. Here are some key strategies:

Pre-Dormancy Irrigation

• Deep Irrigation: Apply a deep irrigation before the onset of dormancy to ensure adequate soil moisture during the winter months. This can help prevent root damage and stress.
• Soil Moisture Monitoring: Use soil moisture sensors to track soil moisture levels and determine the need for pre-dormancy irrigation.

Post-Dormancy Irrigation

• Gradual Application: As the trees begin to emerge from dormancy, gradually increase irrigation to support new growth.
• Avoid Waterlogging: Be cautious not to overwater, as this can lead to root rot and other problems.
• Monitor Soil Moisture: Continue to use soil moisture sensors to guide irrigation decisions.

Dormancy Breakup in Almonds

Dormancy Break Up: Upon degradation of hydrogen cyanamide-a nitrogen-based chemical compound sprayed in the flower buds-nitroxil and cyanide are released. This brings forward the flowering time in apple, apricot, peach, persimmon, sweet cherry flower buds, etc., when compared to untreated plants.

Using Cyanamide or Other Methods

Dormancy Breakup is a critical process in almond orchards, as it influences the timing of bloom and ultimately affects yield and quality. While natural factors like temperature and day length play a significant role, growers often resort to artificial methods to induce or accelerate dormancy breakup.

Cyanamide: A Common Method

Cyanamide is a widely used chemical that can hasten dormancy breakup in almonds. By applying cyanamide to the dormant trees, growers can:

• Advance bloom: Induce earlier flowering, which can be beneficial in regions with late frosts.
• Improve fruit set: Enhance pollination and fertilization, leading to higher yields.
• Synchronize bloom: Ensure more uniform flowering, which can improve pollination efficiency.

Application:

• Cyanamide is typically applied as a foliar spray to the dormant trees.
• The optimal application timing varies depending on the region and the desired degree of dormancy breaking.

It’s essential to follow the manufacturer’s instructions carefully to avoid damage to the trees.

Other Methods:

While cyanamide is a popular choice, other methods can also be used to induce or accelerate dormancy breakup:

• • Mechanical Shaking: Gently shaking the trees can stimulate budbreak.
  • Heat Treatment: Applying heat to the trees can hasten dormancy.
  • Irrigation Management: Carefully managing irrigation can influence dormancy break.

Factors to Consider:

• • Regional Climate: The effectiveness of different methods can vary depending on the local climate.
  • Tree Variety: Some almond varieties may respond differently to dormancy-breaking treatments.
  • Desired Bloom Timing: The specific goals of the grower, such as avoiding frost or synchronizing bloom, will influence the choice of method and timing.

Caution:

• Over-application of dormancy-breaking chemicals can damage the trees.

It’s essential to weigh the potential benefits against the risks and to consult with local agricultural experts for specific recommendations.

In conclusion, while natural factors play a significant role in dormancy breakup, growers can utilize various methods, including cyanamide, to influence this process and optimize almond production. By carefully considering the factors involved and following best practices, growers can effectively manage dormancy breakup and enhance the overall health and productivity of their orchards.

Fruit Growth and Development

Maintaining adequate soil moisture during rapid fruit growth is crucial to prevent yield losses and quality issues. While nut trees are generally more tolerant to water stress than fruit trees, excessive deficits can still affect fruit development and quality.

Almond kernel development occurs in three distinct phases. The first stage involves rapid growth of the hull, shell, and integuments. Water stress during this period can lead to nut drop and smaller kernels.

The second stage is marked by rapid kernel expansion and the hardening of the shell. Almonds are particularly sensitive to water deficits during this phase, and water demand is high.

The final stage, the pre-harvest period, involves the completion of hull, shell, and kernel differentiation and the accumulation of solids in the kernel. The timing of hull split and the formation of the abscission layer, which signal maturity, are influenced by irrigation. Excessive water can prolong hull split and delay harvest, while insufficient water can result in tight hulls.

Harvesting

The harvest period is a critical time for almond trees. While water needs are generally reduced compared to earlier growth stages, proper irrigation management is still essential for optimal fruit quality and tree health.

Post-Harvest

Unlike most nut trees, almonds require post-harvest irrigation to replenish tree reserves and support the following year’s crop, especially after heavy yielding seasons. Adequate water and fertilizer application during this period is crucial for optimal tree recovery and growth.

Key Points

• Early season irrigation is vital for almond tree health and productivity.
• Consistent irrigation during fruit growth is essential for optimal yield and quality.
• Post-harvest irrigation is particularly important for almonds to ensure good fruit set in the following year.
• Monitoring tree health is crucial for determining irrigation needs throughout the season.

Water-Saving Practices for Almond Orchards:

Immediate Strategies

• Water Budgeting: Create a drought management plan by estimating monthly water requirements for each orchard section using historical data. This helps prioritize water allocation.
• Irrigation Scheduling Devices: Install soil moisture sensors to accurately monitor soil water levels and schedule irrigations more precisely. Tensiometers are a good option for many orchards, but more sophisticated devices might be needed for intensively irrigated areas.
• Irrigation System Maintenance: Regularly check for leaks, blockages, and meter accuracy. Poor system efficiency can exacerbate water losses during drought.
• Avoid Leaching: Prevent water from draining below the root zone by monitoring soil moisture levels and irrigation depth. Consider soil salinity testing to determine if strategic leaching is necessary.

Additional Considerations

• Weather Conditions: Hot and windy weather can increase water loss through evapotranspiration, requiring adjustments to irrigation schedules.
• Water Budgeting and Scheduling: Use ETo figures to determine cumulative water use and seven-day forecasts to prioritize patches.
• System Hygiene: Avoid wasting water during system flushing by directing it towards the orchard.
• Soil Salinity: Be aware of potential salinity issues in water during drought conditions and adjust irrigation accordingly.
• Reduced Irrigation: Most almond varieties can tolerate a period of reduced irrigation before harvest without significant yield impacts.
  However, excessive water stress can lead to hull splitting and reduced kernel quality.
• Monitor Soil Moisture: Closely monitor soil moisture levels to avoid both over- and under-watering.
• Avoid Waterlogging: Excessive water can lead to root rot and other soil-borne diseases.
• Consider Variety: Some almond varieties are more sensitive to water stress during harvest than others.

Specific Strategies:

• Gradual Reduction: Gradually reduce irrigation frequency and application rates as harvest approaches.
• Monitor Hull Split: Adequate water supply is essential to prevent hull-tight issues.
• Post-Harvest Irrigation: While not as critical as in previous stages, post-harvest irrigation can support tree recovery and prepare for the next season.

Additional Tips

• Soil Salinity Management: If using saline water, consider leaching to prevent salt buildup.
• Irrigation System Efficiency: Ensure optimal irrigation system performance to minimize water loss.
• Weather Monitoring: Utilize weather data to adjust irrigation schedules based on changing conditions.

Water Quality

Using poor quality irrigation water can lead to severe problems, including soil salinization, alkalization, and plant toxicity, which can damage crops and degrade soil health. High levels of sodium (RAS > 9), chlorine (> 355 mg/L), and boron (> 3 mg/L) are particularly detrimental to almonds. While the electrical conductivity (EC) of irrigation water is also important, its impact varies depending on other factors. Generally, an EC between 1.1 and 3.2 dS/m is considered acceptable.

Irrigation System

Drip Irrigation: A Water-Efficient Solution

Drip irrigation is a highly efficient and economical method for watering yards and gardens. It’s particularly well-suited for drier climates and is gaining popularity in the Northeast. Unlike traditional sprinkler systems, which can lose up to 30% of water to evaporation and runoff, drip irrigation delivers water directly to the plant roots, maximizing its use.
Originally used primarily in commercial settings, drip irrigation is now being adopted by homeowners. It’s ideal for vegetable gardens, perennial beds, trees, and shrubs.

Benefits of Drip Irrigation:

• Water Efficiency: Reduces water waste and conserves resources.
• Disease Prevention: Minimizes water contact with plants, reducing the risk of disease.
• Weed Control: Keeps areas between plants dry, hindering weed growth.
• Time and Money Savings: Efficient system saves time, labor, and water costs.
• Improved Plant Health: Consistent moisture levels promote healthier plants.
• Reduced Leaching: Prevents water and nutrients from draining below the root zone.

Sprinkler Irrigation in Almonds: A Comprehensive Guide

Sprinkler irrigation is a common method used in almond orchards to deliver water to the trees. It involves spraying water over the orchard using a network of pipes, sprinklers, and emitters. While drip irrigation has gained popularity in recent years due to its efficiency, sprinkler irrigation still has its place in almond production.

Advantages of Sprinkler Irrigation:

• Versatility: Sprinkler systems can be used on various soil types and terrains, making them suitable for a wide range of almond orchards.
• Cooling Effect: Sprinkling water can help cool the orchard, reducing heat stress on the trees and improving fruit quality.
• Weed Control: Sprinkler irrigation can indirectly control weeds by creating a favourable environment for beneficial organisms that prey on weed seeds or seedlings. For example, the moist conditions created by sprinkler irrigation can encourage the growth of beneficial fungi that can suppress weeds.
• Nutrient Distribution: Sprinkler systems can be used to apply fertilizers and other nutrients to the orchard.

Disadvantages of Sprinkler Irrigation

• Water Loss: Sprinkler irrigation can be less efficient than drip irrigation due to water loss through evaporation and runoff.
• Weed Growth: If not managed properly, sprinkler irrigation can promote weed growth in non-irrigated areas. Sprinklers provide a consistent source of moisture, which is essential for weed germination and growth. This can be especially problematic in areas with low rainfall or during dry periods. In addition, sprinklers can also help to increase/reduce soil temperature inducing better soil conditions for weed growth.
• Uneven Distribution: Sprinkler systems can sometimes have difficulty providing even water distribution, especially in windy conditions or on uneven terrain.

Best Practices for Sprinkler Irrigation in Almonds

To maximize the benefits of sprinkler irrigation in almond orchards, consider the following practices:

• Proper Design: Ensure the sprinkler system is designed to provide adequate water coverage and avoid over- or under-irrigation.
• Regular Maintenance: Inspect and maintain the sprinkler system regularly to prevent clogging and ensure proper operation.
• Water Scheduling: Use soil moisture sensors or weather data to optimize irrigation schedules and avoid overwatering.
• Wind Protection: If wind is a significant factor in your region, consider using windbreaks to improve water distribution.
• Combination with Drip Irrigation: In some cases, a combination of sprinkler and drip irrigation can be beneficial, especially for young trees or specific areas of the orchard.

Best Practices for Sprinkler Irrigation in Almonds

Both sprinkler and drip irrigation systems are commonly used in almond orchards, each with its own advantages and disadvantages. Here’s a comparison:

Sprinkler Irrigation

• Method: Water is sprayed through nozzles or emitters, covering a wider area.
• Advantages:
  • Can be used for larger areas.
  • Can cool the orchard, reducing heat stress on trees.
  • Can help control weeds through competition with water.
• Disadvantages:
  • Can be less efficient due to water loss through evaporation and runoff.
  • May not be ideal for uneven terrain.
  • Can promote the growth of weeds in the non-irrigated areas.

Drip Irrigation

• Method: Water is delivered slowly and directly to the root zone through a network of pipes and emitters.
• Advantages:
  
  • Highly efficient, minimizing water loss.
  • Can be used on various soil types and terrains.
  • Reduces weed growth by limiting water availability to non-target areas.
  • Can be used to apply fertilizers and other nutrients.
• Disadvantages:
  
  • Can be more expensive to install and maintain.
  • May require more frequent cleaning to prevent clogging.
  • Can be susceptible to damage from rodents or other pests.

Choosing the Right System for Almonds

The best irrigation system for almonds depends on several factors, including:

• Climate: Drip irrigation is generally more efficient in hot, dry climates where water conservation is crucial.
• Soil Type: Drip irrigation is well-suited for a variety of soil types, while sprinkler irrigation may be more challenging on sandy or rocky soils.
• Terrain: Sprinkler irrigation can be more effective on flat terrain, while drip irrigation can be adapted to uneven slopes.
• Budget: Drip irrigation systems can be more expensive to install and maintain than sprinkler systems.

In many cases, a combination of sprinkler and drip irrigation can be used to optimize water use and address specific needs within an almond orchard. For example, sprinkler irrigation may be used during the early stages of tree growth to promote rapid development, while drip irrigation can be implemented later to conserve water and reduce weed growth.

By carefully considering these factors and consulting with Rivulis irrigation experts, almond growers can select the most appropriate irrigation system for their specific orchard conditions and achieve optimal productivity and water efficiency.