Drone technology is unlocking the potential of traditional crop trials and helping to bridge the gap between detailed laboratory studies and field trials.
Drones were used to assess an oilseed rape trial this spring at a site in Yorkshire, gathering data that hasn’t been possible before.
The trial is a collaboration between Envirofield, Agrii and Yara. Envirofield is a crop research organisation that conducts independent trials. In 2022 it was acquired by Origin Enterprises, Agrii’s parent company.
Will Baldwin, director of Envirofield, says the business has maintained its independent status in the Origin group, but also benefits from being part of a bigger organisation. Most recently, this has included access to higher level technology via Agrii’s research and development drone technology to enhance trial assessments.
Will says: “Envirofield acquired a drone five years ago, but we didn’t have the capability to conduct assessments. It just gave us a nice visual perspective of a trial, with only the obvious differences showing.”
Jonathan Trotter, technology trials manager for Agrii has been operating the drone to assess the trial. He uses photogrammetry, a method in which the drone maps the trial with hundreds or thousands of high-resolution images stitched together for analysis.
He explains: “The brief from Envirofield was that Yara was interested in counting oilseed rape flowers and understanding how flowering is impacted by the products being tested. The exact details of the trial don’t concern me, my role is to help facilitate their work with the drone.
“I timed how long it took me to conduct an assessment using the drone. From opening my car door, doing the flight, packing the equipment away and finally closing the car door, it took 17 minutes!
“The drone flies across the plots at about 12 metres high. There are 40 plots, about 0.2ha, and the drone captures almost 400 images across the trial.
“Once the images are processed, every pixel equals 0.31cm of resolution,” explains Jonathan.
Agrii uses Solvi to analyse its drone images. Jonathan uploads the data to the platform, which takes about one hour to process.
Using a new tool that Solvi introduced, alongside Agrii’s experience with reflectance, Jonathan used the triangular greenness index (TGI) measurement. He explains that TGI filters out different wavelengths to remove specific colours, such as green and brown, leaving just yellow.
“TGI is perfect for only measuring flowering, which you can record as a percentage cover per plot, giving individual treatment results to monitor throughout the flowering period.
“This couldn’t have been done without a drone,” says Jonathan.
Chris Harrold, YaraVita product manager for Yara UK, says the company is investigating a range of pipeline products based on a mix of nutrients and biostimulants. Their global R&D team has found benefits in using them on flowering crops to improve flowering and pod set.
“We have been working on how we can develop these products in the UK on oilseed rape, peas and beans,” explains Chris.
“When our R&D team placed the trials with Envirofield, they requested a detailed flowering score assessment. Will Baldwin couldn’t imagine how they could accurately deliver this before drone technology was suggested.
“I saw the appeal of that, as did the R&D team. There’s a cost involved, but it’s only a fraction of the cost if we had tried to do it manually.”
The cold spring weather extended the trial’s flowering period longer than expected. Fortunately, since the drone assessments are relatively quick to conduct, Jonathan has been able to add additional assessments to cover all of the flowering.
Meanwhile the R&D team have been speaking to colleagues in Canada who expressed an interest in the work. They want to know if the methodology can be replicated in their country and if it works on other crops.
Chris continues: “Yara has been on board with the work from the outset. The results at the end of the year will reveal the benefits of the products we are testing. Regardless, I believe in the approach and can see its value in different crops and scenarios.”
He hopes to repeat the work next year to gather further data on Yara’s new products and expects the drone assessments to be an important part of the research.
Drone data enhances confidence in trials
Collecting data using drones allows Envirofield to have an archive of evidence showing how it produces its datasets from trials. Will Baldwin believes it gives companies placing trials with them confidence in their work.
He says: “We report what we find in the field at the time of assessment. The digital images taken by the drone can be revisited anytime to see exactly how the dataset was made. With traditional visual assessments, we rely on the eye of the assessor. If another party wants to look at the images, they can if they have permission.”
Will sees potential for drones to fill gaps in our understanding of new products as they go from being tested in glasshouses to small plot and tramline trials.
“What is possible in a glasshouse is not achievable in a field. If there are only one or two plants growing in a pot in a glasshouse, you can measure any physiological or pathological aspect you want in detail,” says Will.
“Once you scale that up to in-field measurement, assessment becomes more subjective due to the large area you must cover to include variability across each plot. We could use two trial agronomists to conduct an assessment depending on what is required. This helps to alleviate any unconscious bias in the data, but that doesn’t always eliminate it.”
In the short term, Will says drones will enable trial contractors to conduct assessments in the field that could previously only be done in a controlled environment. Looking further ahead, he believes they will make it possible to capture even minor differences and account for spatial variation across much larger-scale (tramline) trials and more frequent assessments possible.
He concludes: “Our job in R&D is to give growers the confidence that the data we are collecting is done in conditions that reflect growers’ actual practices.”
Drone in a box to allow autonomous operation
Although the drone assessments only took 17 minutes, Jonathan Trotter had a three-hour round trip to get to the site. Authorisation by the Civil Aviation Authority (CAA) of the ‘drone in a box’ (DiaB) concept for trial use could eliminate the travel time and allow Agrii to assess the trials remotely and more frequently.
Jonathan explains: “Fully autonomous flight would allow us to capture the data daily to see exactly when the plots started flowering, and monitor that through the whole period to count how long each plot is flowering for and how extensive it was.”
In May, Agrii installed one of the first DiaB systems to be used for trial plot data collection and analysis in the UK at one of their sites in Yorkshire. The team is collaborating with DroneAg via Skippy Scout on this project.
“For now, we must use it with a person monitoring the drone as it flies autonomously. We have to be there with a visual line of sight and be able to take control if necessary,” says Jonathan.
“This is part of the process for us to prove autonomous drone flights are safe and possible to receive authorisation for fully autonomous flights.”
He expects Agrii to receive approval in 2025. The process is complex, with authorisations granted on a company-by-company basis. The CAA assesses each case on its merits, creating a high bar for the investment required.
