byJohn McDonald

Industry Development Manager (NGIQ)

IAL ConferenceJune 2014

Research & DevelopmentResearching the application, absorption and

use of irrigation water in container plant production

Utilising the best science to assess what are the water use processes within the container

Apply the best technology to use what we discovered for application at the grower level

7 years of on-farm assessment in QLD

Presentation will address:

Why did we do it?

What did we do?

How did we do it?

What results came out of it?

What does it mean?

Why did we do it?Impact on plant production

DroughtingWater loggingFertiliser leaching

Cost of irrigation water deliveryEnergy $$$

Irrigation water availabilityIncreasing costPressure on access & volumes

Plant production costsDispatchLabour Industry statistics

• irrigate 4.5 times longer than required• twice the amount of water that can be used• delivery uniformity 75% of optimum

Data from production nurseries in regional Queensland 2012/2013

Energy Saving by Irrigation Efficiency

1. Installation of a recycling system reducing energy 2. Review schedules to increase time between irrigation and increased drawdown of available

water3. Conversion of growing area to drip irrigation4. Improved scheduling5. Changes to scheduling method6. Improved scheduling and rationalisation of growing areas7. Rationalisation of growing areas8. Improved irrigation layout9. Upgrading pump technology to variable speed pumping

Data from South East Queensland production nurseries (n = 24)2012/2013

20%

32%

Investigated available ‘soil’ moisture technologyTensiometersCapacitance probesVolumetric moisture probesetc

Assessed the technology against:Effectiveness in measuring moisture contentAbility to link to controllers for automationAvailability of units in AustraliaCost of units in Australia

RESULTIdentified NEW technology was required

What did we do?

How did we do it? Investigated loadcell technologies used for gravimetric weighing

in other sectors - research, weigh bridges, etc.

Designed and conducted a proof of concept trial investigating weight based irrigation scheduling (WBIS) using loadcells (Stage 1)

Expanded the proof of concept trial to establish a larger trial to investigate WBIS against common scheduling methods of timed and ET (Stage 2)

Established a research trial to measure and assess the process of application, absorption and use of irrigation water in container plant production plus the ability to develop a self learning algorithm to accommodate root and vegetative growth impacts on weight and water absorption (Stage 3)

Completed the final controlled phase to test all aspects of the research and provide final data prior to field trials (Stage 4)

Implementing a field trial to test the research at a field level under normal operating conditions (Stage 5)

How did we do it?

What are the results?Weight Based Irrigation Scheduling:

can be applied and is effectiveout performs common irrigation methods of:

timed irrigation (set run times/season) evapotranspiration (ET) scheduled

can be automated to provide real time datacan be operated via an irrigation controllercan use a representative sample of the crop

Prototype controller error

WBIS applies 30% – 40% less water over a cropping cycle

Rain event at 12:30 pm increasing the Timed and ET zone weights followed by an irrigation event the next morning. Rain event not shown in WBI zones due to CC determination the previous day.

Timed irrigation occurring daily but overall container weight gradually reducing due to excessive evapotranspiration over several days.

No irrigation container weigh drops

No irrigations for 2 days due to zero ET loss then irrigations starting as ET losses increase. Container weight still dropping until rain event.

No irrigations for 3 days until irrigation trigger weight is reached then again 2 days later.

Container capacity irrigation event

Rain event at 12:30 pm increasing the Timed and ET zone weights followed by an irrigation event the next morning. Rain event not shown in WBI zones due to CC determination the previous day.

What does it mean?Automatic irrigation scheduling based on plant water

use is achievableThree key resources are required:

1. A weighing platform (loadcells) for field placementWaterproof and connected to a controller

2. An electronic irrigation controllerCapable of interpreting weight based dataIncludes common controller features

Multiple stations, frost control, multiple start/stop timers, etc

3. Knowledge of plant water use (high/medium/low)Group like water users (crops) together from experienceUse a database that groups plants by water use

WBIC screen showing trigger points percentages for the water content method and the volume of water in the container.

WBIC monitoring screen for total container weight, note the high alarm due to excessive rainfall

WBIC - LoadcellWBIC node connects loadcells to WBIC

Container Capacity (CC) irrigation event is scheduled at 25 day intervals – irrigation water is applied until container stabilises at a constant weight then shuts down. The WBIC establishes this as the new CC weight and adjusts percentages for re-fill and stop points by the same percentage as the water holding capacity that is lost.