Pressurized Irrigation System in a Cherry Orchard
A drip irrigation system irrigates the field frequently over time, ensuring consistent applications of water at low volumes. Because this irrigation system is in such constant use, ensuring that each section of the pipe is working effectively and that the system is set at a level optimal for all plants, is difficult.
Using the MicaSense Altum, researchers were able to monitor this system and found surprising correlations between biomass and plant stress that lead them to identify which trees were struggling with the irrigation method and which were thriving.
Compared to other surface irrigation systems, in drip irrigation systems water is applied at lower volumes and more frequently. In these systems, the installation and design are crucial to providing plants with the required amount of water at any stage of the crop. Clogging, the presence of leaks and other factors that can affect water delivery have an impact on the irrigation system performance and can result in plants being under or over-irrigated, both having a negative impact on the crop.
With extreme heat events occurring more and more frequently, the performance of these systems has to be assessed more regularly to ensure that enough water is being applied to the plants in order to meet their water requirements and prevent episodes of severe water stress. It can be also the case that on these periods with extreme temperatures and for a specific design and volume of soil wetted, the plant water requirements are not met because the root density is insufficient for that given day rather than because not enough water is being applied.
Data collected with the Altum sensor can be useful for the performance assessment of these irrigation systems and can provide helpful information to correct possible issues.
A single flight (120m. AGL) was taken over a drip-irrigated cherry orchard in Hanwood, NSW, Australia in the summer of 2019 to monitor the canopy temperature of the trees and to assess the irrigation system performance. The imagery below shows the temperature and NDVI maps obtained from the LWIR, red and near-infrared bands captured with the MicaSense Altum sensor. The temperature map showed that there were areas with a higher temperature than others indicating that trees from those areas were not transpiring at the same rate than cooler trees from other areas of the orchard. Thermal data alone was useful in detecting those areas where trees were not transpiring at the potential rate.
However, when the temperature map was contrasted with the NDVI it was evidenced that most of the areas with higher temperatures corresponded to trees with a higher NDVI, suggesting that the big trees in the orchard were struggling with the applied irrigation scheduling.
This detailed integrated thermal and NDVI/Biomass data captured from the Altum sensor is really powerful to get an in-depth understanding of how irrigation systems are performing and what management levers can be used to increase productivity. In this case, modifying irrigation schedules and adding drip emitters in areas with higher vigor trees have the potential to overcome this water stress and maximize yield.