US: A team of scientists from the University of New England (UNE) are testing satellite technologies as a mean to track the health and growth of tropical tree crops, including avocados, mangoes, macadamia and bananas.
The team is a part of the Agricultural Remote Sensing Team (ARST) at the university’s Precision Agricultural Research Group (PARG). The researchers are investigating whether satellite-based remote sensing technology.
If succeeds, it can help in providing accurate measures of crop yield, fruit size and quality. The method will also help farmers to better manage crop inputs and make more informed decisions regarding harvest scheduling and forward selling.
At present, yield forecasting of tree crops such as avocado is undertaken by counting the fruit of a small number of trees, then extrapolated across the entire farm – a process both labour-intensive and inaccurate.
An initial evaluation of satellite imagery coupled with targeted field sampling has indicated this approach to be more accurate for both avocado and macadamia. Using satellite imagery allows differences in individual tree health to be clearly seen across an orchard.
When calibrated with actual fruit yield parameters, the imagery can be converted into surrogate fruit yield, size and quality maps.
The UNE team, in collaboration with the University of Queensland, University of Sydney, Central Queensland University and Queensland Department of Agriculture and Fisheries, has been sampling mango, banana, macadamia and avocado orchards across four Australian states, as part of an ongoing project funded by the Federal Rural Research and Development For Profit scheme and Horticulture Innovation Australia.
The scientists use satellite imagery, as well as a number of other 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, 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.
Once sampled, the varying yield parameters are correlated with 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 growing regions and across seasons.