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Autonomous site-specific irrigation control: engineering a future irrigation management system. Dr Alison McCarthy , Professor Rod Smith and Dr Malcolm Gillies National Centre for Engineering in Agriculture Institute for Agriculture and the Environment mccarthy@usq.edu.au.
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Autonomous site-specific irrigation control: engineering a future irrigation management system Dr Alison McCarthy, Professor Rod Smith and Dr Malcolm Gillies National Centre for Engineering in Agriculture Institute for Agriculture and the Environment mccarthy@usq.edu.au
NCEA’s irrigation research Water storage and distribution Infield application Monitoring tools Technology support
Cotton irrigation in Australia • Cotton industry accounts for >20% of irrigation water used in Australia • Site-specific irrigation automation presents opportunities for improved water use efficiencies
Need for automation in surface irrigation Surface irrigation is common in Australia Furrow – cotton, grains, sugar Bay/Border – pasture Labour cost and labour shortage Siphons started manually Cut-off time determined manually
Surface irrigation automation hardware Automation is often time based and inflexible Currently lacks ability to adapt to field conditions Rubicon automation hardware and software: (already in commercial use in Dairy Industry)
Variable-rate technology for LMIMs User-defined prescription maps Four out of 100 growers in Georgia with variable-rate Farmscan systems are still used Poor irrigation prescription support Farmscan
Irrigation automation research Automation enables high resolution data capture and analysis and control Hydraulic optimisation Real-time adaptive irrigation control On-the-go plant and soil sensing technology Internet-enabled sensing and control integrated into the irrigation system
Surface irrigation hydraulic optimisation Real-time optimisation of surface irrigation using ‘AutoFurrow’ Real-time optimisation typically involves: Inflow measurement Time for advance front to about midway down the field Real-time estimation cut-off time that will give maximum performance for that irrigation
Real-time adaptive irrigation control Actuation Sensors Control strategy • Control methodology developed that can adapt to different irrigation systems and crops Actuation Sensors Control strategy
VARIwise control framework Use sensed data to determine irrigation application/timing ‘VARIwise’ simulates and develops irrigation control strategies at spatial resolution to 1m2 and any temporal resolution Control strategies based on difference between measured and desired performance
Irrigation control system - strategies Surface irrigation system Overhead irrigation system 1. Sensors 2. Control strategy 3. Real-time irrigation adjustment
Iterative Learning Control (ILC): Uses the error between the measured and desired soil moisture deficit after the previous irrigation, . . . to adjust the irrigation volume of the next irrigation event. ‘Learns’ from history of prior error signals to make better adjustments. Iterative Hill Climbing Control (IHCC): Tests different irrigation volumes in ‘test cells’ to determine which volume produced desired response Model predictive control (MPC) A calibrated crop model simulates and predicts the next required irrigation, i.e. volumes and timings according to evolving crop/soil/weather input separately for all cells/zones can choose alternative end-of-season predicted targets Adaptive control strategies
How much infield data is needed? Iterative Learning Control (ILC) – best where data is sparse Model Predictive Control (MPC) – needs intensive data set to maximise yields
Irrigation control system - sensors Surface irrigation system Overhead irrigation system 1. Sensors 2. Control strategy 3. Real-time irrigation adjustment
Plant sensing platforms Ground-based platform for surface irrigation Vehicle-based platform for surface irrigation Overhead-mounted platform for centre pivots/lateral moves
Soil-water variability sensing • Estimated by correlating electrical conductivity and infield soil-water sensors
Advance rate sensing using cameras Image from 8m high tower: Image from 20m tower:
Irrigation control system - actuation Surface irrigation system Overhead irrigation system 1. Sensors 2. Control strategy 3. Real-time irrigation adjustment
Adaptive control of surface irrigation Accurate hydraulic models are available to determine irrigation application distributions Link hydraulic model to a crop production and soil model and control strategy: Crop model estimates crop response to different irrigation applications Control strategy determines irrigation applications Hydraulic model determines spatial distribution of irrigation
Surface irrigation adaptive control trial Controlled flow rate to achieve irrigation depths along furrow
Advance rate monitoring Real-time optimisation of flow rate from advance rate Before adjustment: After adjustment:
Irrigation control system - actuation Surface irrigation system Overhead irrigation system 1. Sensors 2. Control strategy 3. Real-time irrigation adjustment
Adaptive control of centre pivot irrigation • Three replicates of MPC, ILC and FAO-56 with different targets and data inputs (weather, soil, plant) • One span with flow meters, valves
Weather, soil and plant measurements Infield weather station: • Variability in soil types • High rainfall season 617mm rain Electrical conductivity map On-the-go plant sensor:
Irrigation adjustment • Irrigation application controlled on one span Lower irrigation flow rate: Higher irrigation flow rate:
Adaptive control of centre pivot Plant data input led to higher yield than only soil and weather data input
Autonomous irrigation management Autonomous irrigation management is achievable Field trials Using plant sensing and adaptive control strategies for surface and centre pivot irrigation systems With reduced labour and water applied, improved yield Further research on data types and resolutions required for adaptive control Further work proposed for commercial scale trials
Vision – precision irrigation framework Integrated irrigation decision-making tool for the cotton industry Demonstrate, evaluate in other crops and regions Optimise both irrigation and fertiliser application - in cotton industry up to 30% nitrogen lost
Acknowledgements Cotton Research and Development Corporation for funding support Lindsay Evans, Nigel Hopson, Neil Nass and Ian Speed for providing field trial sites Dr Malcolm Gillies for programming support Dr Jochen Eberhard for data collection assistance