Imagery obtained from cameras mounted on unmanned aerial vehicles (UAVs) could help growers and consultants to identify crop areas deficient in nutrients and at increased risk of attack from insects.
These images could enable growers to inspect these areas at ground level to confirm nutrient deficiencies and detect insects, resulting in early, targeted and cost-effective treatment of crops.
This is the finding from research funded by the Grains Research and Development Corporation (GRDC), the University of Western Australia’s (UWA) Institute of Agriculture and the Department of Agriculture and Food (DAFWA).
The research was conducted at a CSBP trial site at Williams where canola was sown on gravelly, sandy loam soils, with various potassium (K) fertiliser treatments, and was led by DAFWA researcher Dusty Severtson as part of a PhD project undertaken at UWA.
Mr Severtson found that areas of K-deficient canola could be accurately classified using reflectance data from a multispectral camera mounted on an eight-rotor remote controlled UAV.
“The highest accuracy (99.9 per cent) was at 120 metres above ground level and at flowering about four months after seeding,” he said.
“However, very high accuracies were found at this height at the four-to-eight leaf growth stage (92 per cent) and stem elongation/pre-flowering growth stage (99 per cent) as well.
“Furthermore, the research showed that leaf area indices (LAI) – or overall leaf cover – were considerably reduced in four-to-eight leaf canola, meaning that mapped regions displaying reduced LAI could be targeted for on-ground inspection early in the season.”
Mr Severtson said the research also confirmed that green peach aphid numbers were substantially higher on K-deficient plants than on K-sufficient plants, confirming that plants lacking in K were more susceptible to pests and diseases.
“Grain yields from K-deficient canola in the trials were up to 47 per cent lower than canola with adequate levels of this nutrient, due to the effect on plant growth and damage from insects,” he said.
“This highlights the importance of K, which research shows is becoming increasingly deficient in many WA cropping soils.”
Mr Severtson said that while most growers were not currently using UAVs over their crops, there was a widespread view in agriculture that they were part of the way of the future.
“The use of UAVs and multispectral cameras could help growers to move further away from blanket applications of fertilisers, herbicides and insecticides and further towards detecting and specifically targeting specific areas of paddocks,” he said.
Andreas Neuhaus, of CSBP, who assisted with the trials, said the emphasis in the use of this technology was on crop monitoring and early identification of variability in crop performance across paddocks.
“Plant tissue tests or inspections can then provide further insights which, depending on the season and crop stage, can be acted on either in the current year or be used for planning for the next season,” he said.
Dusty Severtson, DAFWA
0427 196 656
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827