An Initial Investigation Into the Potential and Limitations of High Resolution PLMR and Thermal Image Data for Assisting Irrigation Scheduling in High Value Horticultural Crops
J. Hornbuckle, D. Smith, O. Merlin, J.P. Walker and E. Christen
Power Point Presentation
Irrigated agriculture uses 72% of total water diversions while generating approximately $40 billion dollars annually to the Australian economy and is an important regional industry within Australia. Currently increased pressures have been placed on water resources due to water scarcity and competition from other consumptive and environmental users. This has seen the irrigation industry, particularly in high value cropping systems, place a large emphasis on monitoring rootzone water availability and scheduling irrigations to achieve maximum water use efficiency and minimise water loss below the rootzone. Current rootzone soil water availability monitoring has generally been undertaken using a series of point source methods focused on soil moisture probes using capacitance or resistance based techniques. These do not providea an adequate representation of spatial variability effects in irrigation systems. During November 2006 a detailed field experiment was undertaken in the Murrumbidgee Irrigation Area of New South Wales, Australia to investigate the potential application and relationships between on-ground and airborne measurements using a Polarimetric L-band Mulitbeam Radiometer (PLMR) and thermal imager. Extensive soil moisture measurements (1148 individual gravimetric measurements) were taken on a 24 ha field site covering drip and flood irrigated vineyards. These were compared with data collected from the PLMR sensor for predicting soil moisture availability in the top 5cm of soil. Thermal imagery data was compared against on-ground electromagnetic surveys (EM38) and soil moisture deficits to investigate the spatially variable effects of osmotic (salinity) stress and its effects on plant transpiration. This paper presents initial results from the relationships found in the experiment and further analysis is also described in the paper. Potential applications of such remote sensing platforms are also discussed from an irrigated horticultural perspective.