Australian almond orchards are water dependent production systems that are almost entirely located within the irrigation districts of the Murray Darling Basin. These districts are susceptible to periods of climate induced water scarcity. Improving the accuracy of almond irrigation scheduling tools would not only improve the drought tolerance of the nation’s top horticultural export crop, but also lessen the demand upon the Basin’s surface water systems.
This project aimed to improve the climate resilience of almond orchards by matching irrigation schedules to canopy size and crop water requirements. The project demonstrated the practical benefits of integrating high resolution canopy imagery into commercial irrigation scheduling tools. Under-tree imagery systems were installed at multiple almond orchards to monitor the size and shape of different almond canopies through the 2022/23 irrigation season. Various tree genotypes, ages, densities and training systems were assessed.
Canopy size data was used to improve estimates of crop coefficients and inform real-time estimation of orchard water. With the successful demonstration of this concept, the project’s commercial partner (SWAN Systems) may be able to integrate the output of the under-canopy camera systems into their irrigation scheduling software.
Project description:
Almonds have a high demand for water, with the application of 14 ML/hectare per annum being common in mature orchards. Across the more than 52,000 ha of almonds in Australia, this represents approximately 722 GL, or 10% of the water available for irrigation in a full allocation year from the Murray Darling Basin. Water is a major production cost for almond growers, at approximately $350 per ML plus on-costs (the water price varies between seasons) it can account for almost 40% of an orchard’s operating costs. Inefficient irrigation scheduling may result in either under or over irrigation resulting in poor tree growth, lower yields and waste of water and other resources such as fertilisers.
Estimation of irrigation requirements using the FAO-56 methodology is widely adopted, using local weather to calculate the potential crop water use (reference evapotranspiration) and a crop specific coefficient (KC) to account for differences between crops and changes in water requirements as crops develop during the season. Researchers have used a range of methods to assess canopy size, including satellite images, shaded soil surface area and physical measurements; but these are not widely used by the industry, due to the high cost of application and the lack of automated options. This project aimed to validate the use of under-canopy camera systems in a mature almond orchard and then demonstrate their ability to estimate canopy size in a range of varying almond production systems (including different varieties, densities, training systems and ages).
Activities were focused across three areas to demonstrate the potential use of under-canopy cameras to improve irrigation scheduling.
- A validation of the interaction between canopy size and water use, as measured by sap flow in a canopy reduction demonstration trial.
- Demonstrating the value of under-canopy imagery in defining canopy size and the correlation between camera data and that of other canopy sizing tools.
- Demonstration of under-canopy imagery tools for predicting crop water use across a range of different canopy ages, varieties, densities and genotypes.
The under-canopy cameras were able to accurately predict tree water use. This offers the potential to improve irrigation scheduling (especially in spring) and save water (and associated fertigation). This will support growers through reducing production costs and increasing profitability and the wider industry through improving irrigation credentials and the sustainable use of water resources.
Due to the short timeframe of the project the output of the cameras was not able to be directly linked into the SWAN Systems irrigation software. However, this software has the facility for the canopy coefficient to be included as an input into its irrigation scheduling calculations. Now that the under-canopy camera system – including the camera location, processing pipeline and close relationship to tree water use and other measures of canopy size has been demonstrated. The cameras’ ability to transmit the canopy photos means that that the images could be used to inform the irrigation scheduling software in real time.
Key achievements and results:
The relationship between canopy size and water use of plants is well established. The aim of this project was to demonstrate that an under-canopy camera system was able to monitor canopy growth in orchards to support improved irrigation scheduling.
Through a short de-branching assessment, the project confirmed that the canopy coefficient of individual almond trees was directly relatable to the shaded area beneath the canopy and that there was a strong correlation between under-canopy imagery and crop water use as measured by sap flow sensors. This correlation was validated for under-canopy cameras positioned approximately 1 m from the trunk, suggesting that the commercial use of such sensors within an orchard environment would not be challenged by orchard machinery and standard management practices.
The project then demonstrated permanently installed under-canopy timelapse imagery systems across a set of 37 different canopy combinations that integrated variables such as tree age, variety, training system and planting density. The cameras proved their ability to track changes in canopy size, particularly the latter half or the season as the trees progressed through harvest and into senescence.
Due to the short timeframe of the project the output of the cameras was not able to be directly linked into the SWAN Systems irrigation software. However, this software has the facility for the canopy coefficient to be included as an input into its irrigation scheduling calculations. Now that the under-canopy camera system – including the camera location, processing pipeline and close relationship to tree water use and other measures of canopy size has been demonstrated. The cameras’ ability to transmit the canopy photos means that that the images could be used to inform the irrigation scheduling software in real time.
Further to meeting the contracted deliverables of the project, this project’s research and demonstration activities will have a legacy through the inclusion of under-canopy monitoring systems in SARDI’s perennial horticulture research programs. These programs continue to inform multiple industries upon the implications of orchard design and genetics on a production systems water use and associated resilience to climate change.
Further information: