Good crop, bad crops
Orchardists could soon benefit from space age technologies, allowing them to increase yields and manage crops more efficiently.
Mapping our food from space will soon be the norm. Scientists from the University of New England, in New South Wales, are testing satellite technologies as a way to track the health and growth of tropical tree crops, including avocados, mangoes, macadamia and bananas.
The scientists – Andrew Robson, Muhammad Moshiur Rahman and Jasmine Muir from the Agricultural Remote Sensing Team within the university’s Precision Agricultural Research Group – are investigating whether satellite-based remote sensing technology can provide accurate measures of crop yield, fruit size and quality.
If successful, growers will have access to up-to-date parameter-specific maps within a growing season to help them identify areas performing poorly. This will allow them to better manage crop inputs and make more informed decisions regarding harvest scheduling.
At present, yield forecasting of tree crops such as avocado is undertaken by counting the fruit of a small number of trees, then extrapolating that figure across the entire farm. An initial evaluation of satellite imagery shows it to be more accurate for both avocado and macadamia crops. Satellite imagery shows differences in individual tree health across an orchard.
The UNE team, in collaboration with the University of Queensland, University of Sydney, Central Queensland University and Queensland Department of Agriculture and Fisheries, is sampling mango, banana, macadamia and avocado orchards across four Australian states as part of a project funded by the federal Rural Research and Development For Profit program and the grower-owned Horticulture Innovation Australia.
The scientists use satellite imagery, ground and airborne sensors, to measure the health or vigour of individual tree canopies via their spectral characteristics. From this information, measures such as the Normalised Difference Vegetation Index (NDVI), a scale commonly used to determine the amount of live green vegetation in a given area, is used to select specific trees for targeted field sampling. The varying yield parameters are correlated against additional vegetation indices to identify that which produces the strongest relationship.
For avocados in Bundaberg, Queensland, the team identified a correlation between a number of vegetation indices and fruit weight, both as tree yield and for individual fruit. These results are being validated across other regions and across seasons. Satellite sensing might also enable farmers to better determine the quality and maturity of fruit across an orchard. This will lead to greater efficiencies at harvest time.
The strong correlation between satellite imagery and fruit size over three seasons allows growers to adopt targeted harvesting to pick only those areas of an orchard that bear large fruit.
Although further research is needed to validate these results, if confirmed the technologies investigated through the entire project have the potential to revolutionise the Australian tree-cropping industry, and potentially other agricultural sectors as well.
MAPPING OUR TREE CROPS FROM SPACE HELPS BETTER TO TARGET HARVESTS