A review of Centre Pivot and Lateral Move installations in
the Australian Cotton Industry P Smith, J Foley, S Priest, S Bray, J Montgomery,
D Wigginton, J Schultz, R Van Niekerk
Review of CPLM installations in the Aust cotton industry – P Smith – IAL conference 2014
Introduction Australian cotton growers aim to maximise profitability per ML
2001 – review of CPLM in the cotton industry (Foley & Raine) Since then CPLM uptake increased Australian Government water reforms and funding programs
stimulated investment Healthy Headwaters (Qld) funded repeat study in QMDB in
2011 CRDC funded same in 2012-13 for NSW cotton regions Surveys combined to examine changes in design, operation
and management since 2001 Reporting some results today – full report to be published
Survey design and methodology Format of survey was based on 2001 Designed as face-to-face interview, conducted on-farm 58 selected cotton & grains irrigators interviewed from
Southern Qld to Central/Southern NSW Total 127 CPLM systems irrigating 13,969 ha 42% of area CP, 58% LM
Survey format Questions grouped under headings:
– CPLM dimensions and configuration – pump and water supply – operation management and problems– sprinkler packages – tyres and wheels– farming system – crop water requirements – application strategies – system performance and productivity – runoff management – agronomic considerations– maintenance– purchase decision making
Results and discussionNumber and area of CPLM systems 2011-12 66% are centre pivots compared to 76% in 2001 proportion of area covered by centre pivots has declined by
roughly the same percentage average area under individual systems has reduced for both
centre pivots and lateral moves
Centre Pivot
Lateral Move
Number of systems 57 (76%) 18 (24%)
Total Area (ha) 2915 (55%) 2385 (45%)
Mean Area (ha) ~70 ~165
Centre Pivot
Lateral Move
Number of systems 121 (66%) 63 (34%)
Total Area (ha) 5901 (42%) 8068 (58%)
Mean Area (ha) 51 139
2011-122001
Results and discussionYield and Water applied Water applied by CPLM approx 30% less than furrow irrigation Yields similar
Irrigation Water Use Index (IWUI) 2011-12
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CPLM Furrow
Results and discussionAdoption drivers Main factors 2011-12 labour saving (74%), water saving (62%) Compared to the 2001, labour saving replaced water saving as
main driver Automation declined a lot: 58% 2001, 24% 2011-12
Results and discussionLabour requirement 2011-12:
– CP 47% thought labour less than ¼ of furrow – LM 56% thought labour ¼ to ½ of furrow
2001: – CP 69% thought labour less than ¼ of furrow – LM 53% thought labour ¼ to ½ of furrow
2011-12: 59% considered higher skill required for CPLM
Results and discussionSystem capacity System capacity is important for CPLM design – affects ability to
meet crop water requirements Irrigators were asked for the System Capacity of their CPLM Check: also calculated from pump flow rate and area irrigated
(provided by irrigators)
Results and discussion Design system capacity range 4–32 mm/day 78% CP operators within 1 mm/day of calculated value 46% LM operators more than 2 mm/day from calculated value –
probably due to variable area
Difference between stated and calculated Design system capacity (Fig. A: CP, Fig. B: LM)
Results and discussion
System capacity Managed system capacity allows for machine downtime and
application losses Better indicator than Design system capacity
Results and discussion 20% of CPLM more than 110% of peak ET (18% 2001) 25% between 90% and 110% of peak ET (36% 2001) 55% below 90% of peak ET
Designed system capacities (left) and Managed system capacities (right) expressed as % of average Peak January ET
Results and discussionSystem capacity 59% of Design system capacities more than 110% of peak ET
(26% 2001)– irrigators are increasingly understanding the importance of
adequate system capacity for meeting crop water needs However, there are now a greater proportion (55%) with
Managed system capacity that cannot meet peak water demand (46% 2001) – concerning!
Results and discussionPressure and costs Higher running costs of CPLM considered a
disadvantage Should have pressure no higher than necessary Most systems have pressure regulators 15 psi or
less Commonly recommendation: supply point pressure
max 15 psi above regulators ie. Max supply point 30 psi
Results and discussion 52% operating above 30 psi – 2001 59% – room for more
improvement None operating above 50 psi – 13% in 2001
Results and discussionPressure and costs Supply point pressure average 19 psi >regulator, range 0–40 psi 21% operating at >30 psi pressure difference 79% have potential to save energy costs
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Results and discussion
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Pressure regulators require min 5 psi above rated pressure to operate properly – 4 systems not operating properly
4 systems 40 psi above regulator pressure
Results and discussionEmitter Systems Emitter systems changed a lot between 2001 and
2011-12 – LEPA systems reduced 48% to 19%– moving plate sprinklers increased 4% to 54%
May be due to:– slight differences in study participants – more
grain in 2011-12– previous concerns about sprinklers on cotton not
eventuating (pollination effects, lint quality) Change consistent with 2001 report –
recommended performance be improved by converting from static to moving plate
Pressure regulators used more widely – 95% v. 58% in 2001
Results and discussionPower Supply and Control Systems Proportion of diesel powered machines increased – 79% v 65%
in 2001 Remaining 21% used mains power – all CP 90% of machines surveyed were electric drives, 10% hydraulic CP: 53% electric drive powered by diesel generator, 42%
electric drive powered from mains, 5% hydraulic drive powered by diesel motor
LM: 71% electric drive powered by diesel generator, 29% hydraulic drive powered by diesel motor
Automatic control use increased – 40% v 10% in 2001 – Still low considering potential reduction in labour and
increased flexibility
Results and discussionWheel Rutting and Bogging 64% experienced problems with wheel ruts or bogging – 79%
in 2001 Still a prevalent issue – but mostly minor problems overcome
within first few seasons 59% of respondents have or will modify their irrigation strategy
or sprinkler set up to help overcome this – most used ‘boombacks’ and half-throw sprinklers around the towers
Many irrigators commented on need to check tyre pressures and use of different tyre configurations to alleviate bogging
Results and discussionScheduling Capacitance probes are the tool most commonly used 2001: generally used one scheduling tool 2011-12: used combination of tools – both for furrow and CPLM CPLM apply less water more often – so operators more
conscious of water use under these
Results and discussion Depth per CPLM irrigation range 5–50 mm, median 24 mm
– 52% applied 15–30 mm (33% in 2001)– 11% fewer growers applied 15 mm or less– 7% fewer applied more than 45 mm
Depth applied per pass (Fig. A 2011-12, Fig. B 2001)
Results and discussionFertiliser usage
Fig. A: Change in total seasonal fertiliser use with CPLM fertigation (2011-12)
Fig. B: Change in pre-season fertiliser use with CPLM fertigation (2011-12)
Results and discussionCapital cost of CPLM systems Range $610 to $6,000 per hectare, median $2,570 per hectare
(lowest cost included second-hand equipment) 2001: $1,250 to 2,500 per hectare 70% between $1500 and
$3500 per hectare– Large range due to
individual site requirements – cost of machine, install machine, pumps, earthworks, electrical works, system capacity, currency exchange rates
Results and discussionCapital cost of CPLM systems Generally, costs decrease as irrigated area increases Stronger for LM than for CP CP: cost for irrigating same area varies by multiple of six Engage an independent expert to evaluate designs and
provide advice!
Results and discussion
38% use flow meters to monitor changes or problems in delivery
62% visually assessed emitters Only 25% had measured uniformity – range 50% to 100%
(90% is benchmark)
System Performance IWUI – discussed earlier 93% of irrigators surveyed had flow
meters or pressure gauges for system control
79% used pressure points as an indicator of problems
Thank you!
