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Optimising irrigation in kiwifruit orchards using microwave remote sensing

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posted on 03.03.2022, 01:20 authored by eRNZ AdmineRNZ Admin, Istvan Hajdu, Ian Yule

Aotearoa New Zealand’s kiwifruit sector contributed 38%, by far the highest value to horticultural exports in 2020. The current outlook sees global trade volumes continuing to rise by 45% by 2025 and by 2030, the sector’s GDP contribution will double. As a response, a further 2800 hectare is being licensed to kiwifruit production in the next few years. However, water access has been identified as one of the main risk factors that investors will face. Furthermore, growers are already progressively required to justify their water take through rigorous reporting depending on the use of surface water, ground water or community water schemes.

Therefore, managing water resources sustainably is crucial to New Zealand’s horticultural sector. We know we must manage these resources by optimising the use of rainfall and applied water to avoid water stress in crops. Irrigators are being required to monitor their use of water and many now use soil moisture measurement (through probes in the ground) as a means of better informing their irrigation management. While this is a major step forward and accurate information can be provided for the point measured, it is also recognised that orchard soils are often highly variable and further methods need to be implemented to create a cost-effective measurement network.

This project uses Synthetic Aperture Radar (SAR) which is a form of microwave sensing to provide a series of spatial maps of canopy water status to monitor water stress. The first crop it will be used in is kiwifruit. Microwave remote sensing technology can offer a viable method of capturing plant stress variability over individual orchards and blocks, with a high level of granularity and regularity. This granular information can be readily integrated with the accurate point source data from soil moisture probes to create a very effective measurement network. Microwave satellites orbit over New Zealand on a very regular basis providing a number of advantages over conventional optical means, it is not affected by cloud cover, and it captures images day or night. This removes some of the major limitations of optical satellite systems and provides a means of having highly regular and reliable measurement.

The outcomes of this project feed into the development of digital tools for growers utilising this technology that will enable them to make better decisions around increasing their harvestable yield and reducing fruit value variability within the orchard. This project is being run with the cooperation of the industry, including growers and technology providers. Since SAR imagery is available nationwide, the developed tools will ultimately help the wider grower community and assist with precision irrigation strategies that can be applied to eliminate both under and over-irrigation.

ABOUT THE AUTHOR(S)

Dr. Istvan Hajdu
Istvan has built up a career applying his particular skill set to help public bodies and commercial organisations translate complex location-based information and find solutions to particular business challenges. Currently working as a Research Scientist at PlantTech Research Institute, he is applying his wealth of experience in handling geospatial data and Geographical Information Systems (GIS), particularly the integration of GIS and remote sensing with artificial intelligence. Istvan has a strong background in geospatial data sciences due to his various roles as GIS analyst, data, and mapping officer in the United Kingdom. This knowledge was further extended by completing a PhD within the Primary Growth Partnership programme, which explored soil water modelling in New Zealand’s hill country. After finishing his PhD thesis, as a spatial analyst at Massey University, he gained experience in vegetation monitoring, implementing research and geospatial analytics in industry-driven applications by using data from multispectral and hyperspectral imaging.

Professor Ian Yule
Ian Yule is the Research Director for PlantTech Research, he is an experienced leading researcher with a strong track record of working in higher education conducting industry relevant research and commercialisation. Skilled in Precision Agriculture and Agritech, Ian has spent the bulk of his recent career working on contract research in the areas of precision agriculture, agri-technology and remote sensing; with a particular focus on hyperspectral imaging and image analysis. Ian has a strong commercial history. He is co-founder of Hyperceptions, a data processing company analysing aerial hyperspectral imaging data to deliver agricultural insights. Ian is also the founder of Stoneleigh Consulting, which operates both within New Zealand and internationally. They offer technical assistance and consultancy in the areas of Agritech, precision agriculture, agricultural development and technology.

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