This document provides an overview of various tools and methods for managing almond irrigation, including: 1) Almond phenology charts that break down the growth stages of almond trees and their associated water needs. 2) Climate-based scheduling tools like reference evapotranspiration (ETo) and crop coefficients (Kc) that can be used to calculate crop water requirements. 3) On-farm monitoring tools like pressure bombs, soil probes, and trunk sensors that directly measure plant or soil water status for scheduling irrigation.

1. Technology for Almond
Irrigation Management
Tim Kennedy

2. Overview
• Almond Phenology
• Irrigation basics
• Management tools to help schedule irrigation.
• Climate based scheduling (ETo and Epan)
• Visual /Soil auger
• Pressure bomb
• Capacitance probes (EnvironSCAN, MAIT, GreenBrain).
• Phytec (trunk dendrometers)
• Ceres Imaging (Aerial imagery)
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3. Almond Phenology
• Stage 1: Bud swell to early flowering
• Stage 2: Early flowering to petal fall
• Stage 3: Petal fall to early pit hardening
• Stage 4: Early pit hardening to early hull split
• Stage 5: Early hull split until end of harvest
• Stage 6: End of harvest to leaf drop
• Stage 7: Dormancy (leaf drop to bud swell)
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4. Almond Phenology
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5. Almond Phenology
• Almond fruit development
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0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44
Development(%)
Weeks After Flowering
Pericarp
Endosperm
Embryo
Stage 1
(Fruit growth)
Fruit MaturationStage 2
(Kernel growth)
Cell Division
Cell Expansion
Adapted from:
Hawker & Buttrose, 1980
Mesocarp (Husk)
Endocarp (Shell)
Exocarp (Surface)
Embryo (Kernel)
Endosperm
Nucellus
Test (Brown Skin)

6. Almond Phenology
0.30% 1.30%
9.90%
56.10%
30.50%
1.30% 0.60%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
Phase 1 Phase 2 Phase 3 Phase 4 Phase 5 Phase 6 Phase 7
%ofAlmondWaterUseRequirement
Almond Phenological Stages
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• Stage 1: Bud swell to early flowering
• Stage 2: Early flowering to petal fall
• Stage 3: Petal fall to early pit hardening
• Stage 4: Early pit hardening to early hull split
• Stage 5: Early hull split until end of harvest
• Stage 6: End of harvest to leaf drop
• Stage 7: Dormancy (leaf drop to bud swell)

8. Basic Conversions
• 1kL = 1000 litres = 1m3
• 1000kL = 1ML
• 100mm = 1ML/ha
1mm applied over 1ha = 10kL
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9. Basic Formula
Application rate (mm/hr) = L/h per dripper x no. of drip laterals______
dripper spacing(m) x row width(m)
Discharge rate = 2.3 L/hr
Dripper spacing = 0.7 metre
Row width = 7.25 metres
Number of laterals = 2
Application rate (mm/hr) = (2.3 x 2) / (0.7 x 7.25) = 0.91mm/hr
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10. • Quantifying water use:
𝑊𝑎𝑡𝑒𝑟 𝑈𝑠𝑒 = 𝑊𝑎𝑡𝑒𝑟 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑚𝑒𝑛𝑡 ÷ 𝑊𝑎𝑡𝑒𝑟 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦

11. Climate Based Scheduling
Using crop factors to calculate crop water use:
• Cf = crop factor
• ETpan= evaporation pan
• ETc = crop water use
𝐸𝑇 𝑐 = 𝐶𝑓 × 𝐸𝑇𝑝𝑎𝑛
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12. Climate Based Scheduling
Using crop coefficients to calculate crop water use:
• Kc = crop coefficient
• ETo = reference crop evaporation
• ETc = crop water use
𝐸𝑇 𝑐 = 𝐾𝑐 × 𝐸𝑇𝑜
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13. Climate Based Scheduling
• Can’t apply crop coefficients with Epan data and crop factors with reference
crop evaporation, but you can apply a Kpan factor to convert crop factors to
crop coefficients.
• Kpan figures can vary dramatically between 0.35 and 0.85.
• A DPI trial conducted at Lake Powell indicated a Kpan figure of 0.72.
• Kc = 1 ÷ Kpan x Cf
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14. Climate Based Scheduling
However, there is not a one size fits all.
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Set of Cf and Kc have been
developed as a guide to use
through the season.

15. Climate Based Scheduling
• Factors that can effect/change crop factors or crop coefficients include:
• Canopy coverage / leaf area
• Yield
• Property location with respect to Epan/ETo data collection
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16. ETc = (ET x Cf)/Kpan
ETc = Potential crop water use Minutes Required = (ETc /SAR) x 60

18. Pressure Bomb
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21. Capacitance Probes
• Capacitance probes (EnviroSCAN, MAIT, GreenBrain, etc)
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22. Capacitance Probes
• Three possible graphs:
1. Summed graph:
2. Separate level / stacked graph
3. Subsoil graph
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23. Capacitance Probes
• Summed graph:
• The “When to Water” management graph
• Encompasses the rootzone
• A whole-of-picture
• Influenced by all soil and root system layers
• Lots of work and many years required in setting full and refill points
• Changes dramatically in the early years following deep ripping, soil stabilisation and
root system maturity
• More complex interpretation required – there is never just one full or refill point
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25. Capacitance Probes
• Separate level / stacked graph:
• The “Where to Water” management graph
• Encompasses all sensors on the probe – within and below the rootzone
• A whole-of-picture wetting front
• No full and refill points, so doesn’t show you how full the profile is
• Easy interpretation but doesn’t provide whole story
• Best to view with a 14 day time span but can also increase or decrease time span
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27. Capacitance Probes
• Subsoil graph:
• Macro trend of irrigation management and plant water use
• The “Water Bank” management graph
• Encompasses just one sensor at the base of the rootzone or the sensor just below
the rootzone
• Easy interpretation
• Best to view with a 60 day time span but can also increase or decrease time span
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28. Capacitance Probes
• Decreasing Subsoil Moisture:
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29. Capacitance Probes
• Increasing Subsoil Moisture:
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30. Phytech (trunk dendrometers)
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31. Phytech
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Thank you