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Australia • 05 September 2024

Marquis Ag-Tech Field Day

Technology everywhere is moving at breakneck speed and it’s no different in agriculture. Staying informed about, adopting, and implementing new technologies is crucial for boosting productivity. On August 8, Marquis Macadamias held an ag-tech focused field day showcasing technologies macadamia growers can currently use on their orchards.

Multispectral Imagery

Andrew Auld from Proton Consulting, who also grows macadamias in the Northern Rivers, presented first about integrating multispectral imagery in farming macadamias. Following an overview of Geographic Information Systems (GIS), Andrew explained his multispectral imagery work. Multispectral imagery captures images of the land using multiple light wavelengths, beyond what the human eye can see. Variations in light reflectance provide information about tree health, water stress, nutrient levels and other important characteristics. The relationships between differing reflectances are described as Vegetation Indices (VIs). VI analysis helps identify variation within orchards, blocks and even between trees. This granular data, with a resolution representing 5cm on the ground, assists growers to make more informed management decisions earlier, especially when combined with other GIS layers.

Figure 1: NDVI image of a macadamia block (left) and an adjusted NVDI (right)

Figure 1 A Normalized Difference Vegetation Index (NDVI) image from one of Andrew’s macadamia orchards. High reflectance (green) indicates healthy vegetation. Low reflectance (blue) indicates low health or soil. The right section of the image has been changed to dichromatic (two colour) image with everything below average health blue and everything average and above health yellow.

For more information you can email Andrew at: Andrew@protonconsulting.org

Yield Monitoring

Figure 2: Sensor and logger (left) and sensor mounted on harvester (right).

James Auld, Andrew’s father, then presented on a yield monitoring unit they are developing. Starting over 15 years ago, the initial protypes used impact sensors with the current, farm-tested prototype using optical sensors on a robust 3D printed mounted frame (Figure 2).

The yield monitor uses nut counts from the sensor data and GPS locations to create a yield map across the orchard (Figure 3). When multi-year yield map data is overlayed with other GIS layers, like multispectral images, it provides a better view of orchard variability. This enables more targeted management practices and assessment of those practices over time.

Figure 3: Macadamia yield map.

Partnering with the NSW DPI Farms of the Future project, the yield monitor is fitted to a harvester on the DPI Alstonville Centre for Tropical Horticulture farm to prove the concept and validate the unit. For more information or to register your interest on the macadamia yield monitor email: info@protonconsulting.org.

Figure 4: Macadamia Weather Network station locations (left) and display from a station (right).

Macadamia Weather Network

Macadamia crop protection is fundamental to ensure productivity and quality. Orchard spraying is under consistent public scrutiny so it’s critical to have access to accurate and record, reliable and defensible weather data. Leoni Kojetin from the Australian Macadamia Society presented on sourcing local weather information for macadamia growers.

Growers have access to different weather information like the Bureau of Meteorology (BOM), internet sites like Elders weather and on-farm stations. Each with different pros and cons. The best weather information for spray decisions and weather data recording is an on-farm station.

The AMS has established the AMS Macadamia Weather Network (MWN) to provide a better option for growers. The MWN accesses current weather data from a collection of on-farm stations in Qld and NSW. The six NNSW station locations are shown in Figure 4. There are 26 stations in the Queensland network, from Gympie to Mackay.

The MWN is a free service, available to all macadamia growers, that provides current, simple and accurate weather data. For AMS members to access the Macadamia Weather Network login to your AMS members dashboard and look for the heading ‘Macadamia Weather Network’. If you are not currently an AMS member you can contact the AMS office on office@macadamias.org or phone 1800 262 426 to register and gain access. If you have a Davis weather station or are looking to install one, you can add your station to the MWN by emailing weather@macadamias.org.

Drone Orchard Spraying

The highlight of the day was the presentation by local macadamia growers Steve Ferndale and Paul Duncan on their recent experience using a drone to spray part of their orchard.

Their orchard is 40-50 years old, contour planted, mixed varieties on relatively steep slopes. The drone spraying was initially undertaken on a ‘particularly troublesome block’ which couldn’t be sprayed with an airblast sprayer, following the wet weather in 2021/22. The farm also uses a spray contractor, making spray windows even smaller.

Scott from Skytech with the Marquis Grower Services team conducted some spray coverage tests with different water rates and achieved sufficient coverage given the size of the trees.

Figure 5 A typical photo of the trees in Steve and Paul's orchard.

Steve explained that as use of the drone seemed to have been successful, it was decided that for the 23/24 season they would allocate one portion of the farm to spray only with the drone and harvest it separately to compare drone to the air blast sprayer.

 The drone trial area was selected as this was consistently the most difficult area to access. Roughly half of the trees in the drone sprayed block were older trees and the other half were the younger ~14 year old trees.

The quality results from the five consignments from the drone-sprayed block (Table 1) have reasonable consistency in insect damage levels.

Table 1: Drone consignment quality results.

Elevated reject in the third consignment was due to an area of the block only able to harvest for the first time this round due to the wet 2024 harvest.

The overall quality comparison of the 23/24 season, shows negligible differences in saleable kernel and a minor difference of 0.16% in reject kernel (Table 2).

The yield per hectare cannot be compared with the remainder of the farm as the drone sprayed area contained most of the younger trees, approximately 50% of the drone area. Results in the drone sprayed area were either comparable to, or better than the results in the same blocks last year.

Table 2: Quality comparison of between drone and standard spraying.

For Steve, the big advantage of the drone is you can spray regardless of ground conditions, which is one of the main restrictions in their orchard. Also, drones don’t damage your orchard floor in wet conditions like an airblast sprayer and tractor and use 85-90% less water. Cost is comparable to using a contractor and, importantly, the quality results are similar to ground sprayed trees.

Unfortunately, most of the new, softer chemistry isn’t registered for aerial application and tall trees close to the orchard edges trigger the drone crash avoidance system which means trees on the orchard edge may not be sprayed.

Figure 6: Skytech's mobile refilling and recharging station

Steve emphasised that moving to spraying by drone is just ‘changing your perspective’. Growers are conditioned to seeing large volumes of water pushed up into the canopy, fighting against gravity. In contrast, drone spraying uses gravity and air displacement from the drome propellors to agitate the canopy, push water down to help with coverage. Modern spray drones aren’t little toys, they’re big drones and the air displacement they generate is impressive.

Steve finished by highlighting that work is still required to optimize nozzle and droplet sizes, and to refine the flight path to maximise coverage and the quantity of chemical used.

Demonstration of Drone Orchard Spraying with Skytech Solution

Scott Fisher from Skytech Solutions presented, on and demonstrated, drone orchard spraying and fertilising.

All new orchards must first be mapped the orchard to determine flight paths. Young trees require a single pass, but mature trees require 5 m wide transects. The mapping is included in the service and is repeated annually to account for tree growth.

Drone payloads differ for fertiliser or liquid. Fertilisers have a 50 kg payload, and liquids are 42 L. Skytech bring 1000 L to the site which will cover up to 6 ha, depending on tree size, but large blocks need access to good quality water. The mobile station means Skytech can set up anywhere to refill and recharge (Figure 6).

Skytech, with the help of Mark Whitten from Marquis, conducted a spray coverage test the day prior to the field day with plain water (Figure 7). The first test was performed on extremely challenging trees, under gusty conditions, with the test paper approximately 2 m from the top of the tree. The gusty wind, consistently over the general threshold of 10 km/hr, altered both the drone angle and spray direction. Given the conditions, and with no spreader used, the results were reasonable. In the second test the trees were smaller, and the test paper was positioned at the top of the trees. The water sensitive paper on the left of Figure 7 shows the spray coverage achieved on the large trees (~11 m) shown in Figure 8 and on the right the smaller trees (~9 m).

Water rates are always being refined, but it does depend on the size of the tree. Higher rates of 250 L/ha are used on bigger trees, and the rate is dropped to 100-150 L/ha on smaller trees.

Figure 7: Spray coverage result on water sensitive paper. Large trees shown in figure 8 (left) and smaller trees (right). Water rate 250L/ha

To spread fertiliser the drone is fitted with a spinner to spread over a wider area, or the spinner is removed so that the fertiliser falls in a narrow band: roughly 0.8 m wide. The narrower band is well suited to the younger orchards (Figure 9). As all fertilisers are different, the spreading is calibrated on site to give the required amount on a grams per meter basis.

Skytech Solutions website is here.

Figure 8: Test pole (left) and the drone spraying water on a test flight (right) on trees ~ 11m tall.

Figure 9: Targeted strip spreading with a drone.

Marquis Macadamias would like to thank all presenters for contributing to an excellent day and all growers who gave up their valuable time to attend.