Australian Avocado Irrigation Review overview

This article draws from content sourced from the Avocado Irrigation Review Final Report. The authors being Simon Newett, Bridie Carr and Ebony Faichney, Department of Agriculture and Fisheries, Queensland, and Liz Singh, Avocados Australia Ltd.
This photo appears courtesy of QDAF.


The Australian Avocado Irrigation Review (also referred to as an ‘Advanced Management Workshop’) is one of three reviews scheduled as part of the project “Avocado extension and development” project (AV17005).

The ultimate purpose of the avocado irrigation review is to provide information that will help improve avocado irrigation in Australia.

The review consisted of four components:

Part 1: Survey of current avocado practices in Australia
Part 2: Survey of international avocado irrigation trends
Part 3: Avocado irrigation literature review
Part 4: Face-to-face summit of key growers, consultants, extension staff and invited speakers to evaluate the information gathered and identify appropriate practices and research needs.

Participants in the summit were selected from expressions of interest to provide a good representation of irrigation knowledge and needs across Australia. They included key growers, consultants, extension staff and invited speakers.

All of the information gathered, and recommendations made will be used to guide future research, development and extension of irrigation across the Australian avocado industry.

A report called the ‘Australian Avocado Irrigation Review’ presents the information generated by the review. This report and more including presentations, a webinar recording of the key note speaker at the summit, and the 71-page literature review can be found on the Avocados Australia Ltd Best Practice Resource, simply type “Irrigation review” into the search box. It is located in the ‘Library’ section under ‘Event Proceedings’, ‘2021 Avocado Irrigation Review’




Challenges identified included:

  • Water availability and limited allocations
    • Deteriorating water quality
    • Infrastructure constraints
    • Soil variability
    • Range of different climates and climate variability
    • Design and capacity of old irrigations systems
    • Lack of education, knowledge and access to information
    • Poor soil quality
    • Labour skills and cost
    • Monitoring for decision making
    • Water use for optimal outcomes
    • Large numbers of small to medium growers and lack of knowledge
    • Drainage & erosion
    • Site selection
    • More efficient use of electricity and choice of the most suitable tariff.
  • Heat waves – stomata closing early
    • Low humidity
    • Adoption of drip irrigation and its management challenges
    • Over irrigation from the need to use overhead irrigation for frost control



  • Israelis conduct very good and ongoing irrigation research. Due to their shortage of water, they have adopted drip irrigation and learnt how best to use it.
    • The importance of a thorough soil survey of the site and careful land preparation, including drainage.
    • Chileans can get good irrigation uniformity, despite poor soils, by careful and extensive pre-plant land preparation.
    • Advanced irrigators practice a high standard of irrigation system maintenance which includes cleaning out irrigation lines as standard practice, most commonly with phosphoric acid.
    • Advanced irrigators are more proactive than reactive in irrigation scheduling and place importance on current and forecasted evapotranspiration.
    • As well as frequent referral to soil and plant monitoring tools, advanced irrigators also physically check soil moisture (with a spade or auger), often examining root health at the same time.
    • Israelis consider that the ‘winning combination’ for irrigation scheduling is to monitor both the soil and tree and interpret results together.
    • There is strong interest in ‘dashboard’ software that brings monitoring and weather information together.
    • Greater use of salt tolerant rootstocks.
    • Leaching irrigation practices where salinity is an issue are tailored to soil texture and the results from analysing soil and/or leaf mineral levels.
    • Awareness of the high oxygen requirement of avocado roots and the challenge this creates in trying to balance soil moisture and oxygen requirements.



Udi was one of the two keynote speakers at the irrigation summit, he joined via zoom from Israel where he is currently the chief agronomist with Granot, he also consults internationally and has previously worked in the Israeli department of agriculture as an extension officer.

A recording of Udi’s presentation is available on the Best Practice Resource.

The notes below are key learnings by the summit delegates from Udi’s presentation.

  • The bigger the root system the better
    • Even if you have a small root system, you need to have enough irrigation capacity for high demand – water demand is driven by the size of the canopy
    • Drip – there is apprehension in Australia about conversion to drip but the Israelis have learnt to do it
    • Israel was forced to make changes – lets follow their example in Australia
    • In dealing with saline water:

o Need to collect EC data (30cm root zone)
o Leaching practice is “horses for courses”

  • Drip irrigation

o Matching emitters to soil type, taking into account water quality
o Use certified irrigation designers (e.g. ‘Irrigation Australia’ approved)
o Learn from expertise in other crops

  • Irrigation is always evolving; practices need to be re-examined every 3-4 years
    • Israelis already use ‘dashboard’ software to integrate monitoring data for scheduling purposes, especially when they have dual systems (under tree & overhead)
    • We need to be less insular & look beyond just avocados
    • The literature review raised topic of soil aeration as new information, however in Israel this is common knowledge
    • Traditionally in Australia we water at night & at the weekend for lower tariffs, but power costs are not the only consideration. In Israel they irrigate when the crop needs water which is during the day. Daytime irrigation has reduced irregular bearing.
    • Drip irrigation requires a higher level of management. Need to predict 2-3 days ahead. Need to be proactive with drip, not reactive.


Dr Michael Forster was one of the two keynote speakers at the irrigation summit and attended in person. Michael is a director of Edaphic Scientific and an Adjunct Senior Research Fellow at Griffith University.

The notes below are key learnings by the summit delegates from Michael’s presentation.

  • Dendrometers can measure down to 1 micron (one hair strand is 60 microns across).
    • Growers like simple guidelines and figures to follow.
    • Tensiometers provide a universal value that is applicable across a range of conditions. The development of the digital tensiometer is a significant breakthrough.
    • From a panel member who uses dendrometers:

o Good for picking up problems earlier.
o Greater insights and therefore confidence.
o Still likes simplicity.

  • From another panel member who uses dendrometers:

o Don’t use for planning.
o Helps with irrigation strategy.
o Interface is easy to use.

  • Dendrometers are explaining how fruit drop is related to weather events.
  • Sap flow:

o Sap flow measurements are explaining water use differences between cultivars in macadamias.
o In a PhD study in macadamias, sap flow gives a better understanding of water relations.
o Sap flow might stop even when roots are well supplied with water because stomata have closed.
o Can it be useful for studying the effect of salinity?
o Concept is good but caution advised for using sap flow meters commercially at this point, and they need to be more robust.

  • There was surprise about how high soil water soil tension values are in other crops to trigger irrigation compared to avocados. Avocados have a trigger value of about 14cB (7cB in Perth sands) compared to 58cB in macadamia, 150cB in apple/pear, and 386cB in citrus. Do we need to conduct research to verify the trigger value in avocado?
    • We need to develop crop factors for different environments around Australia.
    • There is an app available to measure leaf area.
    • Physiologically best to base crop factor on leaf area.
    • Sap flow readings:

o Need to know trunk size for understanding water usage.
o Need to be calibrated on farm (17 calculations).
o Need to know wood density & trunk diameter.

  • Sap flow meters can be put on petiole, branch, trunk, root. Change position every 3 months. Avoid injection sites.
    • Approximately $900 per sap flow sensor. Start with one block to get a feel & understanding for the technology. They can be integrated with other systems.
    • Tensiometers are easiest to understand. Other systems need more knowledge.



Work with a combination of professionals (e.g. irrigation consultants and avocado agronomists)

Water supply & water quality

  • Ascertain volume of water available in good and bad years.
    • Limit size of orchard to the number of trees that can be irrigated fully. Avocados can’t be half irrigated.
    • Conduct water quality analyses and investigate the water quality history.

Soil properties

  • Undertake a thorough grid survey of the soil in order to produce a soil map to understand the site and plan accordingly. Set orchard block boundaries according to soil type. Design the irrigation system to suit the situation. The soil survey needs to include:

o Depths and soil texture of each horizon.
o Water infiltration rates.
o Readily Available Water (RAW) values (be aware that infiltration rates and RAW can change over time so re-measure every few years).
o Consider doing an electromagnetic (EM) survey but ensure that it is ground truthed.

  • Thorough and careful land preparation is needed to:

o Achieve good drainage (water must not pond anywhere).
o Prevent mixing subsoil with topsoil.
o Establish well-designed mounds, ensuring they do not dam water.

  • Drainage is critical for avocados and even more important if you also need to flush out salts, so conduct land shaping and install above and below ground drainage where necessary.

Irrigation design

  • Use an irrigation specialist certified by Irrigation Australia (source from Home page of to design an irrigation system tailor-made for your situation.
    • Consult with experts to select the most economical electricity tariff arrangements but also consider tree water needs e.g. Israeli’s have discovered that irrigating during the day (when the tree is using water) reduces irregular bearing.
    • Forecast water needs for a year of peak demand and limit size of orchard to the number of trees that can be irrigated fully in a difficult year.
    • Determine water requirements in week of peak demand and ensure that the irrigation system and capacity can meet these requirements. Peak demand determines overall design.
    • Irrigation design is important to achieve uniform water delivery to each tree across the block.
    • The irrigation system needs to cater for local water and climate issues (e.g. frost, heat, water quality and availability).
    • Undertake ground truthing of specs.
    • Salt flushing and fertigation needs must be considered.
    • Learn how to better manage poor quality irrigation water – e.g. work out frequency and volumes of leaching irrigations needed.
    • Be prepared to review and accept new methods, concepts and technology. Use technology with an open mind.
    • Build flexibility into the system to account for future growth, higher or lower application rates, technical developments, and practice changes. Design a system that can be built upon.
    • Picture selling the block to someone else. Is the design simple, effective and easy to operate?

Irrigation hardware and maintenance

  • Establish a maintenance plan with weekly/fortnightly/monthly/6-monthly and annual tasks. This plan will include:

o Testing irrigation uniformity at least annually. Aim for a high standard, ensure uniformity and system performance is maintained. (There is an instructional video in the BPR called “Checking irrigation uniformity in avocado orchards”).

o Cleaning out irrigation lines at least annually e.g. with phosphoric acid.

o Filter cleaning.

o Regular testing of water and soil.

o Re-assessing depth of root zone.

  • Don’t set and forget. Validate and re-test. Check probes and system performance. Don’t rely on a spec sheet.
    • Review scheduling and the irrigation system itself periodically to ensure it meets the needs of the orchard e.g. in response to changes in tree size, mulching practices, soil organic matter levels etc.

Moisture monitoring

  • Install your own weather station and take daily observations.
    • Follow weather forecasts especially evaporation, rainfall, temperature, humidity and wind predictions.
    • Integrate information from various sources including stage of tree phenology, soil and plant monitoring tools, weather data and weather forecasts.
    • Learn how to be more predictive and less reactive with irrigation needs.
    • Better understand how to use and get the most out of moisture monitoring devices – consult an expert and/or seek training.
    • It is critical to choose sites for soil moisture monitoring devices that are representative. Careful installation is also essential. Establish multiple sites to achieve adequate representation and check soil moisture monitoring sites regularly to ensure that they are still representative, relocate if needed.
    • As well as checking monitoring tools, also physically inspect soil moisture with auger, spade or pit and monitor root health at same time.
    • Establish irrigation trigger point values (for tensiometers) or full and refill points (for capacitance probes).
    • Allocate time and resources to conduct the monitoring and interpretation.
    • When irrigating, also consider soil oxygen levels.
    • Regularly research what tech is available, their plusses and minuses and how they work.


  • Maintaining soil moisture through winter is more important than previously thought.
    • Match irrigation with the phenological cycle and environmental demand.

Agronomic aspects to improve irrigation effectiveness

  • Improve root health primarily through regular mulching. Regular mulching results in higher soil organic matter levels and higher Readily Available Water.
    • Determine and monitor depth of root zone as it may change over time.
    • Be informed about crop phenology and changes in water demand through crop cycle.
    • Plan ahead (4-7 days) but assess daily requirements.
    • Network with supplier, consultants and other farmers especially in your region.
    • Establish an irrigation schedule with assistance from external agronomists and other growers.


  • Use of sap flow in irrigation research including plant water use.
    • Use of Vapour Pressure Deficit for irrigation scheduling and a better understanding of water needs.
    • Potential of pulse irrigation and its cost benefit.
    • The need for ‘dashboard’ software to integrate different sources of information to assist in making irrigation decisions.
    • Recognition of the need for experts to interpret data.
    • The importance of having sufficient soil aeration to match the high oxygen demand of avocado roots.
    • A substantial volume of moist soil is still required if drip irrigation is used.
    • In hot areas, stomata close early but when this happens it is too late to react, growers need a system to monitor in real time to make more timely decisions.
    • Growers need to use evaporation data more extensively.




Sap flow research in combination with dendrometers to establish:

  • How much water avocado actually uses.
    • Crop factors for each stage of the phenology cycle in each region.
    • Maximum and minimum water needs for each tree size, age, phenology, variety, rootstock, soil type and region.
    • Transpiration ratio/plant-water relations/physiology of water use in Australia
    • Water use efficiency (WUE) research.
    • Best time of day to irrigate.
    • Follow development of dendrometers suitable for use in orchards and learn how to use them in an integrated manner with other monitoring tools.

Drip vs sprinkler (in different regions)

  • Better understanding of drip irrigation.
    • Drip irrigation design for the crop and conditions including soil type.
    • Pros & cons.
    • Cost/benefit.
    • Case study/other growers experiences.
    • Learn from other crops e.g. citrus.
    • Converting from mini-sprinkler to drip – what is the recommended transition process?

Best practice guidelines for irrigation

  • Develop a checklist for growers
    • Standardise terminology/common language – develop an industry protocol so we are all talking the same language. E.g. how we compare irrigation – mm/hr or L/hr?
    • What monitoring tools are available, how to use them and where to site them


  • Investigate ‘Dashboard’ software that integrates information from different devices and sources.


  • Assessment of existing and potential rootstocks:for salt tolerance, water use efficiency and good production (not forgetting tolerance to Phytophthora root rot).


  • Best way of monitoring & managing.
    • Better understanding of salinity measurement and management. What are the tree and crop effects under Australian conditions?

Remote sensing technology

  • Follow development of remote sensing and how it may be used to pick up water stress and help with irrigation efficiency and scheduling.

Overhead evaporative cooling

  • How effective is it per region?
    • What are the temperatures to use as trigger points?

Environmental impacts

  • Effect of humidity on pollen viability, and on stomatal activity.
    • Temperature, shade, wind speed,
    • The potential of protective structures (e.g. shade netting).

Drought management

  • How far can we push trees and what is the medium to long term effect on trees in Australian conditions. Research response to extreme weather events.

Soil aeration needs

  • More clarity around soil saturation and soil aeration – establish threshold levels for soil oxygen content for avocado in different soil types.
    • Establish how to irrigate without unduly impinging on soil oxygen content


  • How does tree size affect hydraulic resistance and water use? Smaller trees seem to do better.
    • The Great Barrier Reef regulations in relation to the quality (chemical and nutrient content) of water leaving the property through runoff and leaching.


  • Understanding barriers to adoption of technology & the human component.
    • Determine what best practice looks like for each region.
    • Conduct masterclasses (e.g. irrigation and fertigation), training, webinars.
    • Case studies incorporating cost/benefit studies on investment. Cater for the range of farm sizes, from small to large.
    • Grower education on how to interpret monitoring data.
    • Irrigation study tours



For more information:

Contact Simon Newett, from Queensland Department of Agriculture and Fisheries, on 07 5381 1326 or email


The review is part of the strategic levy investment project ‘Avocado industry development and extension’ AV17005. This project has been funded by Hort Innovation, using the Hort Innovation avocado research and development levy, co-investment from the Queensland Department of Agriculture and Fisheries, and contributions from the Australian government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.

Thanks to all who contributed including the delegates at the summit who were Alan Blight, Eric Carney, Bridie Carr, Sam Collins, Ebony Faichney, Michael Forster, Lisa Fyffe, Fabian Gallo, Jeremy Giddings, Simon Grabbe, Martin Inderbitzen, Tim Myers, Simon Newett, Chris Searle, Liz Singh, Shane Singh, Zac Starkie, and John Tyas.

Author: Simon Newett, Bridie Carr and Ebony Faichney and Liz Singh
Date Published: 08/02/2022