— 19 IREC Farmers' Newsletter No. 201 — Autumn 2019 The popularity of drones all over the world in the last decade and their potential application across industries very diverse in nature has not escaped the attention of the agriculture sector. Agricultural industries have embraced this technology and are excited about its capability for precision agriculture, but also remain wary of the hype associated with the technology. DRONES, also known as unmanned aircraft vehicles (UAVs), are mainly used as platforms where tools and sensors of different types can be attached to perform specific tasks. The constant development of more reliable and easy to use drones with longer battery life, as well as more advanced and miniaturised sensors for use on drones, has awakened the interest of farmers and agronomists in this technology in ways they did not consider in the past. In the last few years, there has been significant research on the study of the applicability of drones in agriculture. At Deakin University’s Centre for Regional and Rural Futures (CeRRF), for instance, research has been conducted to provide more efficient identification of weeds in irrigation channels, which if not treated properly, usually reduce the water flow and affect the efficient delivery of water to farms. Other topics that CeRRF is working on is the study of aerial multispectral and thermal imagery for water and fertiliser decision management in crops. Nowadays, it is clear that drones can do things other than just recording harvesting videos or collecting nice pictures of the crops and landscapes. However there are still a lot of people wondering what services can this technology really provide for farmers. Uses of drones in agriculture Automatic plant counting is now possible from high-resolution images (< 3 cm) taken from drones at low altitude. Agriculture companies either provide this service to their customers or provide them with user-friendly plant counter tools that are useful to assess whether or not replanting is needed in some areas. Crop mapping using aerial multispectral and thermal images (page 18) is one of the most common services provided for monitoring nutrient and plant water status as well as for disease detection. Thermal images show areas of plants with a higher temperature, indicating lower transpiration due to either low soil water availability or a malfunction of the plant vascular system due to disease. Aerial thermal images from drones are also used to evaluate surface and subsurface drip irrigation systems. Multispectral images collect information about the percentage of light reflected by the canopies at specific bands. Data from these bands can be combined to obtain so-called vegetation indices, which depending on bands used, can illustrate differences in plant biomass, chlorophyll content and other crop factors. New sensors are already available in the market that provide thermal and multispectral data simultaneously, which offer the advantage of collecting different types of information with just one flight. Images at one specific date illustrate the existing variability in a paddock and are useful to pinpoint in the field the reasons for that variability and take decisions accordingly to manage it. Examples include thermal flights for identifying leaks in drip systems (Figure 1) and looking at water infiltration (subbing) in surface irrigated beds (Figure 2). Time series of images, on the other hand, provide information about the evolution of the crop as a result of specific irrigation or fertiliser strategies, which is useful to fine-tune the best management practices for a crop locally. — 19 IREC Farmers’ Newsletter No. 201 — Autumn 2019 Drones at the service of agriculture Figure 1. Thermal image of a drip irrigated field showing lateral drip line emitter leaks and main line leaks. Figure 2. Thermal image showing poor lateral movement of water (subbing) across raised beds.