New sensor set to revolutionise crop monitoring

Published 15 October 2010

biomassThe University of New England’s Precision Agriculture Research Group has completed its initial trials of a new crop sensor, named the “Raptor”, that is the first of its kind in the world.

The Raptor is attached underneath a low-flying aircraft and enables rapid scanning of crop biomass over entire paddocks. This “active system” works by directing rapid pulses of red and near-infrared light onto the crop plants and measuring the light reflected back to the aircraft. “The relative reflectance of plants in these two wavelengths is an excellent indicator of plant vigour – be it in terms of actual biomass, or water or nutrient status,” said the project leader, Professor David Lamb.

The sensor, developed by Holland Scientific from Nebraska in the United States, is the culmination of extensive testing involving a prototype sensor that was flown in 2009 by the Armidale-based company Superair. “At that time we had only enough optical power to fly the sensor at four metres above the crop canopy – something the pilots really enjoyed, but not really the safest option,” Professor Lamb said. “It was also limited to level fields.”

The Raptor involves more powerful optics and extra-sensitive detection electronics, and can be operated at heights of 50 metres or more above the crop. This allows deployment over hilly country. Michael Schaefer, a PhD student in the Precision Agriculture Research Group, is working on an even more powerful, laser-based sensor system that will undergo trials early next year.

Funded by the Cooperative Research Centre for Spatial Information (CRCSI) as part of its “Biomass Business” project, the Raptor system was developed to address key limitations in the traditional methods of using satellite or aerial imagery to map crop vigour. The sensor can be easily retro-fitted to any standard crop duster or agricultural spray plane, so that crop scans can be carried out when spraying or fertiliser applications are being done. “But by far the biggest advantage is its flexibility in the collection of data,” Professor Lamb said. “As it uses its own light sources, the Raptor system is able to capture data under cloud and even at night. Conventional aerial or satellite imagery can only be obtained on clear days, and this can be a real problem during peak growing seasons.”

The first test flights were conducted over the “Keytah” property of the CRCSI partner Sundown Pastoral Company, located west of Moree in northern NSW. Another CRCSI partner, Twynam Agriculture, is very excited about the potential of the Raptor. Twynam’s senior agronomist, Nick Barton, said that the system had “great potential – particularly in our Argentinean operations, where we struggle to collect aerial or satellite imagery due to the constant cloud”. “We need these crop biomass maps to enable the application of variable-rate growth hormones,” Mr Barton said, “and the Raptor system potentially offers us a viable alternative to consider when we can’t capture standard airborne imagery.”

The UNE team has scheduled trials later in the year to assess the sensor performance over pastures and sugarcane.

THE IMAGE displayed here shows part of a biomass map that was produced by the Raptor system on a plane flying 30 metres above the ground. Clicking on this image reveals a photograph of Professor David Lamb (right) and UNE Technical Officer Derek Schneider with the Raptor crop sensor attached to the bottom of the Superair fertiliser plane used to test the system.